Poor Running - Need Help
12-30-2001, 01:54 PM
#16
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Thanks for the information, Adrian. Very interesting ...
And, just to muddy the water a little bit more ...
I am aware of a '95 993 owner (Tom) here in Orange County that, after installing a LWF, had a problem with the engine surging badly when accelerating slowly. This was besides the car stalling all the time. In this case, the problem was eventually traced to a bored Fabspeed throttle body that was installed prior to the LWF. Tom had surging before the LWF was installed, but it became much worse when the throttle body was combined with the LWF.
To correct the stalling, Tom installed Andial's extra weight, making it a semi-LWF.
Here's the thread where Tom discusses the fix for his surging and stalling. This thread also links to another excellent thread on LWFs ... great posts by Steve Weiner:
LWF Thread from 993 Board
And, just to muddy the water a little bit more ...
I am aware of a '95 993 owner (Tom) here in Orange County that, after installing a LWF, had a problem with the engine surging badly when accelerating slowly. This was besides the car stalling all the time. In this case, the problem was eventually traced to a bored Fabspeed throttle body that was installed prior to the LWF. Tom had surging before the LWF was installed, but it became much worse when the throttle body was combined with the LWF.
To correct the stalling, Tom installed Andial's extra weight, making it a semi-LWF.
Here's the thread where Tom discusses the fix for his surging and stalling. This thread also links to another excellent thread on LWFs ... great posts by Steve Weiner:
LWF Thread from 993 Board
12-30-2001, 09:37 PM
#17
Burning Brakes
Thread Starter
I looked at my DME part number today and it is as follows: 964 618 124 00. Don't know if this tells you anything more about my issues, but, it does seem odd to me that the LWF would be fine and no apparent performance issues with the A/C off and turn the thing on and it doesn't work good then. The other thing I found today was that the Engine would run fine with A/C on with the fan on setting 0, 1, or 2, but, on 3 it would start to act up. On 4 it would not run at all. Air blows nice and cold, but, engine runs like sh**. That just does not compute for me. If the engine ran poorly all the time then LWF would make sense. As I've told Randall. My last P-car was MUCH less complicated (1986).
BTW - About 2 weeks ago (couldn't find that thread) I had asked about the cost of "THE HAMMER" and it spun into a discussion on my DME. I've provided the part number above and found that swapping the bulb from an adjacent light into the check engine socket lights the check engine light. Hope whoever it was interested in if that would work reads this. It certainly does at least light the bulb. Whether it will give me any valuable info is a different story.
BTW - About 2 weeks ago (couldn't find that thread) I had asked about the cost of "THE HAMMER" and it spun into a discussion on my DME. I've provided the part number above and found that swapping the bulb from an adjacent light into the check engine socket lights the check engine light. Hope whoever it was interested in if that would work reads this. It certainly does at least light the bulb. Whether it will give me any valuable info is a different story.
12-31-2001, 12:58 AM
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Hi Slant,
Just to be clear, when you say the car runs like sh**, you're not just speaking of the idle, right? As discussed above--and in the referenced thread--stalling and an erratic idle are well known side effects of a LWF. That said, I do believe the erratic idle effect is associated with the compressor. If I understand you correctly, your problem is actually associated with the speed of the interior fan. Very odd .... As you're probably asking yourself, what would the interior fan setting have to do with how the engine runs?
So ... you're driving down the road, AC off, say at around 3000 RPM. You nail the throttle, and the car accelerates without a hiccup.
Now turn the AC on, setting at 3, again at 3000 RPM. You nail the throttle, the car hesitates and stumbles--i.e., runs like sh**.
Would the above two paragraphs be somewhat representative of your car's behavior?
When you say the car doesn't run at all with the fan at the 4 setting, do you mean it flat out dies? So, you could be driving down the road--say at 3000 RPM--turn on the AC, put the fan at 4, and the engine dies?
Is your poor running problem a recent development, or has it been present since you purchased the car?
Just to be clear, when you say the car runs like sh**, you're not just speaking of the idle, right? As discussed above--and in the referenced thread--stalling and an erratic idle are well known side effects of a LWF. That said, I do believe the erratic idle effect is associated with the compressor. If I understand you correctly, your problem is actually associated with the speed of the interior fan. Very odd .... As you're probably asking yourself, what would the interior fan setting have to do with how the engine runs?
So ... you're driving down the road, AC off, say at around 3000 RPM. You nail the throttle, and the car accelerates without a hiccup.
Now turn the AC on, setting at 3, again at 3000 RPM. You nail the throttle, the car hesitates and stumbles--i.e., runs like sh**.
Would the above two paragraphs be somewhat representative of your car's behavior?
When you say the car doesn't run at all with the fan at the 4 setting, do you mean it flat out dies? So, you could be driving down the road--say at 3000 RPM--turn on the AC, put the fan at 4, and the engine dies?
Is your poor running problem a recent development, or has it been present since you purchased the car?
12-31-2001, 02:56 AM
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Hi,
Just a thought but I wonder if the alt. might be a bit weak and with the fan on a highter setting the load drops the system voltage down.......causing the dme to act up
Tom
Just a thought but I wonder if the alt. might be a bit weak and with the fan on a highter setting the load drops the system voltage down.......causing the dme to act up
Tom
12-31-2001, 04:28 AM
#20
slant911:
The idea that the problems you're having are being caused or at least influenced by the LWF was a **suggestion** I made...it doesn't mean that's what's causing the problem (I thought I should clarify that because this thread is now taking on a tone that's blaming the LWF for everything when it may not be at fault at all). To explain why some people have problems with LWFs, I've written the following up for you:
One of the primary purposes of the flywheel is to supply the crankshaft (rotating) with a spinning angular mass. If you took a glass dinner plate that weighed, say 1/2 to 1 pound, drilled a hole in the center of it, attached a shaft of, for example, a cylindrical piece of steal about 1/2 inch in diameter and about a foot long, and then set it in a set of bearings and then spun it, the angular momentum of the mass of the plate would keep the whole assembly spinning, and the only significant forces acting to slow it would be those introduced by friction between the bearings and the shaft. Now replace the dinner plate with a paper plate that weighs, say a few ounces. How long will the plate spin compared to the glass dinner plate? Unless you have some REALLY incredible bearings, it will likely continue spinning for a much shorter period of time. I know this is a radical and over simplified example, but it demonstrates something the flywheel introduces to your system called angular momentum.
When people have problems with the LWF setups, it's because, much like the plate comparison above, there's less mass, and it allows the engine to decelerate faster...but it also allows it to accelerate faster (which is the point of the LWF). At idle, the DME is expecting to see a certain level of deceleration because it's been programmed for that. Instead what it sees is a much more rapid deceleration/acceleration of engine speeds which it tries to compensate for by adjusting fuel/air ratios.
A LWF can cause a "bouncing" or erratic idle on some of the cars with the units installed. At idle, the engine decelerates too rapidly because of the LWF, so the DME changes the fuel/air ratio to increase what is sees as a stall about to occur. Because the LWF is lighter, once the engine gets the added power, the LWF allows the engine speed to accelerate, but unfortunately it does so faster than what the DME sees as normal, so the DME then decides it needs to make the engine to slow down. The DME then cuts the power by re-adjusting the fuel/air ratio, the RPMs drop, but once again, too rapidly, so once again the DME thinks it's about to stall, and your now back to where you were at the start of this paragraph. This cycles so you end up with an idle that fluctuates, often between a complete stall and about 1000 RPM. Adding a load, ANY HEAVY load, like the AC, will make the problem worse, and possibly even bring on a stall.
LWF types of problem should only be noticeable at idle, not when the car is in gear and running (the weight of any flywheel is insignificant compared to that of a driven car). Like I said before, LWFs are not all made by a single manufacturer so the actual weight of the flywheel will have something to do with it, as well as your version of DME software. If the problems are at idle, then the LWF is a good suspect. If you're experiencing problems throughout the running range, then it's probably NOT the LWF.
I hope this helped,
Bill Wagner
PS: Randall...a lengthy LWF discussion took place on the older Rennlist site, but it might very well have been before you became a visitor.
The idea that the problems you're having are being caused or at least influenced by the LWF was a **suggestion** I made...it doesn't mean that's what's causing the problem (I thought I should clarify that because this thread is now taking on a tone that's blaming the LWF for everything when it may not be at fault at all). To explain why some people have problems with LWFs, I've written the following up for you:
One of the primary purposes of the flywheel is to supply the crankshaft (rotating) with a spinning angular mass. If you took a glass dinner plate that weighed, say 1/2 to 1 pound, drilled a hole in the center of it, attached a shaft of, for example, a cylindrical piece of steal about 1/2 inch in diameter and about a foot long, and then set it in a set of bearings and then spun it, the angular momentum of the mass of the plate would keep the whole assembly spinning, and the only significant forces acting to slow it would be those introduced by friction between the bearings and the shaft. Now replace the dinner plate with a paper plate that weighs, say a few ounces. How long will the plate spin compared to the glass dinner plate? Unless you have some REALLY incredible bearings, it will likely continue spinning for a much shorter period of time. I know this is a radical and over simplified example, but it demonstrates something the flywheel introduces to your system called angular momentum.
When people have problems with the LWF setups, it's because, much like the plate comparison above, there's less mass, and it allows the engine to decelerate faster...but it also allows it to accelerate faster (which is the point of the LWF). At idle, the DME is expecting to see a certain level of deceleration because it's been programmed for that. Instead what it sees is a much more rapid deceleration/acceleration of engine speeds which it tries to compensate for by adjusting fuel/air ratios.
A LWF can cause a "bouncing" or erratic idle on some of the cars with the units installed. At idle, the engine decelerates too rapidly because of the LWF, so the DME changes the fuel/air ratio to increase what is sees as a stall about to occur. Because the LWF is lighter, once the engine gets the added power, the LWF allows the engine speed to accelerate, but unfortunately it does so faster than what the DME sees as normal, so the DME then decides it needs to make the engine to slow down. The DME then cuts the power by re-adjusting the fuel/air ratio, the RPMs drop, but once again, too rapidly, so once again the DME thinks it's about to stall, and your now back to where you were at the start of this paragraph. This cycles so you end up with an idle that fluctuates, often between a complete stall and about 1000 RPM. Adding a load, ANY HEAVY load, like the AC, will make the problem worse, and possibly even bring on a stall.
LWF types of problem should only be noticeable at idle, not when the car is in gear and running (the weight of any flywheel is insignificant compared to that of a driven car). Like I said before, LWFs are not all made by a single manufacturer so the actual weight of the flywheel will have something to do with it, as well as your version of DME software. If the problems are at idle, then the LWF is a good suspect. If you're experiencing problems throughout the running range, then it's probably NOT the LWF.
I hope this helped,
Bill Wagner
PS: Randall...a lengthy LWF discussion took place on the older Rennlist site, but it might very well have been before you became a visitor.
12-31-2001, 12:43 PM
#21
Burning Brakes
Thread Starter
Randall hit the symptoms on the head. You could be driving down the road at 3-4000 RPM's and everything is fine. Turn the A/C on fan setting 4 and the engine simply dies. To test this further I sat in the driveway and held RPM's at 3000 (in neutral) and turned the A/C on at 0 setting. No difference. RPM's stayed solid. Same thing at setting 1 and 2. At setting 3 the RPM's would start to "wobble". At setting 4 the RPM's would simply go away. And there was no revving or anything else you could do to stop it. I checked the output of the alternator. It checks out O.K. As I said before the battery is new. Hope this helps in determining possible causes.
Thanks again all.
Thanks again all.
12-31-2001, 02:19 PM
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Hi Slant,
Wow, unusual problem you've got there ...
Does the engine only cut-out when the AC is running, or will running the interior fan to the 4 position with the AC off (e.g., with the heat on) also cause the engine to cut-out?
How long have you had this problem?
Seems like the next step is to study your wiring diagram(s), and perhaps figure out an interrelationship between the interior fan, AC and DME?
If you're unable to figure out anything tangible, this sounds like a prime candidate for the "Hammer." In particular, considering that you can reproduce your problem on cue by operating the interior fan.
Bill W. ... sounds like we were on the same page all along. Minor confusion in communications
.
Wow, unusual problem you've got there ...
Does the engine only cut-out when the AC is running, or will running the interior fan to the 4 position with the AC off (e.g., with the heat on) also cause the engine to cut-out?
How long have you had this problem?
Seems like the next step is to study your wiring diagram(s), and perhaps figure out an interrelationship between the interior fan, AC and DME?
If you're unable to figure out anything tangible, this sounds like a prime candidate for the "Hammer." In particular, considering that you can reproduce your problem on cue by operating the interior fan.
Bill W. ... sounds like we were on the same page all along. Minor confusion in communications
.
12-31-2001, 02:44 PM
#23
Burning Brakes
Thread Starter
From what I can tell running the heat in that position is fine. Although I did not test that as extensively as the A/C. A/C load seems to be the problem.
Also, I have not experienced the "typical" stalling characteristics of the LWF. Still not saying for sure that's NOT it, but, seems like an odd jump for a lightweight flywheel to have an affect or effect (not an english major) on the engine when hitting the A/C...
Also, I have not experienced the "typical" stalling characteristics of the LWF. Still not saying for sure that's NOT it, but, seems like an odd jump for a lightweight flywheel to have an affect or effect (not an english major) on the engine when hitting the A/C...
12-31-2001, 04:40 PM
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Adrian:
The "DME brain" part number is:
0261-200-450 (911-618-124-04)
I am the 3rd owner and so I assume it's the original brain for my 1990 C4 Cab (USA).
Yes I mistakenly several weeks ago disconnected the DME "brain" with the battery still connected but the ignition OFF.
I had disconnected the "brain" as I wan't to measure some ohms values from several engine sensors. When I connected the "brain" back up again I got a XMAS tree effect that is intermittent. That XMAS tree effect also sometimes causes that annoying LOUD audio alar. So I disconnected the "central informer" to get some peace from that audio alarm and to halt the XMAS tree effect. Now I have somehow got a always lite air bag and seat belt warning !
I'll try now your suggestion regarding the battery and DME brain 20 min method:
many thanks and Happy 2002 !
Patrick
Adrian wrote:
Patrick. Was this DME the one originally installed. Did you remove it with the battery still connected. If you did then I recommend you disconnect the battery with the DME in place. Wait 20 minutes (yes there is a reason for this) then disconnect the DME. Remove the DME and check the pins and connectors for damage. It is not 100% clear from your post why you played with the DME. What other work have you carried out. Have you played with the ignition system. Have you tried to install a "Check Engine Light".
Ciao,
Adrian
The "DME brain" part number is:
0261-200-450 (911-618-124-04)
I am the 3rd owner and so I assume it's the original brain for my 1990 C4 Cab (USA).
Yes I mistakenly several weeks ago disconnected the DME "brain" with the battery still connected but the ignition OFF.
I had disconnected the "brain" as I wan't to measure some ohms values from several engine sensors. When I connected the "brain" back up again I got a XMAS tree effect that is intermittent. That XMAS tree effect also sometimes causes that annoying LOUD audio alar. So I disconnected the "central informer" to get some peace from that audio alarm and to halt the XMAS tree effect. Now I have somehow got a always lite air bag and seat belt warning !
I'll try now your suggestion regarding the battery and DME brain 20 min method:
many thanks and Happy 2002 !
Patrick
Adrian wrote:
Patrick. Was this DME the one originally installed. Did you remove it with the battery still connected. If you did then I recommend you disconnect the battery with the DME in place. Wait 20 minutes (yes there is a reason for this) then disconnect the DME. Remove the DME and check the pins and connectors for damage. It is not 100% clear from your post why you played with the DME. What other work have you carried out. Have you played with the ignition system. Have you tried to install a "Check Engine Light".
Ciao,
Adrian
12-31-2001, 04:53 PM
#25
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Dear Slant,
Your more recent explanations are a tad different to the original post. However we are getting a little closer from your latest explanation.
There is a direct link between the DME and the airconditioning system. 3 actually.
The DME is told when you engage the aircon system. When you hit the "ON" button a signal is sent to the DME which is short speak, will adjust the idle to handle the extra load. The another input is the condenser fan. The DME is told at which speed the fan is running at. Again to adjust the load and the final input to the DME is the temp control **** position. I would suggest that either one of these inputs are missing or incorrect to the DME.
It also could be mechanical. The compressor could be on the way out, creating too much mechanical load on the engine. Maybe even the clutch.
The first check I would do is with the engine running at idle, engage the airconditioning and see what happens. The RPM should drop to around 700 and bounce quickly back up to 880.
Dear Patrick,
The DME part number you have is the second last one. The last version on normal 964s was the -01.
Unfortunately you could have damaged the DME. As suggested I would also carry out a reset and go for a 15 minute full range drive once more. Airbag system is independent of the central informer. Run via the clock and the airbag control unit.
Hope this helps.
Happy New Year to all,
Ciao,
Adrian
911C4
PS: Problems with the LH Blower fan causing unusual other problems is recorded. This is caused by the incorrect Aircon/Heating control unit being installed. In otherwards the mod for the newer unit has not been carried out. I would certainly chjeck the part number of the aircon/heating control unit just to put this problem area to bed. By the way, it takes around 10 minutes for LH Blower fan problems to start up.
Your more recent explanations are a tad different to the original post. However we are getting a little closer from your latest explanation.
There is a direct link between the DME and the airconditioning system. 3 actually.
The DME is told when you engage the aircon system. When you hit the "ON" button a signal is sent to the DME which is short speak, will adjust the idle to handle the extra load. The another input is the condenser fan. The DME is told at which speed the fan is running at. Again to adjust the load and the final input to the DME is the temp control **** position. I would suggest that either one of these inputs are missing or incorrect to the DME.
It also could be mechanical. The compressor could be on the way out, creating too much mechanical load on the engine. Maybe even the clutch.
The first check I would do is with the engine running at idle, engage the airconditioning and see what happens. The RPM should drop to around 700 and bounce quickly back up to 880.
Dear Patrick,
The DME part number you have is the second last one. The last version on normal 964s was the -01.
Unfortunately you could have damaged the DME. As suggested I would also carry out a reset and go for a 15 minute full range drive once more. Airbag system is independent of the central informer. Run via the clock and the airbag control unit.
Hope this helps.
Happy New Year to all,
Ciao,
Adrian
911C4
PS: Problems with the LH Blower fan causing unusual other problems is recorded. This is caused by the incorrect Aircon/Heating control unit being installed. In otherwards the mod for the newer unit has not been carried out. I would certainly chjeck the part number of the aircon/heating control unit just to put this problem area to bed. By the way, it takes around 10 minutes for LH Blower fan problems to start up.
12-31-2001, 05:17 PM
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Dear Slant,
A couple of extra things. I was distracted by a funny movie on TV.
Firstly it is not a good idea to engage the aircon system over 2000RPM. It will work obviously but this creates a huge mechanical and electrical load. Now I am sure you are nowhere near the upper limit but this summer we had a couple of compressor blow ups.
The other item to remember is "Electrical Load". The electrical system of the 964 can supply around 75 amps and retain voltage. Please remember that with the aircon running you have a very high electrical load from the condenser fan, LH Blower fan and the electro-mechanical clutch. Add to that normal electrical needs, plus in the hot weather the oil cooler fan and the brake hydraulic pump (intermittant). Now add to that headlights, or the stereo running full bore and you have a high electrical load. Now if the rear blower fan also cranks up. Well I think you get the picture. The DME is "VERY" senstive to low voltage. If the voltage drops low enough it will switch to "Emergency Mode" and your C4 will run like crap.
Seems to me, well a possibility that you may have an excess electrical load, maybe being caused by a bad compressor or even the condenser fan.
I think you will have to eliminate the elctrical items, starting with the aircon related units from the picture one by one,
Ciao,
Adrian
911C4
PS: A similar thing happened to me in a tunnel. I had everything burning and turning except lights and aircon. I switched on the headlights as I entered the tunnel and then activated the aircon (it was hot in the tunnel) and suddenly I had a loss of power and it ran like crap. I somehow knew what it was and increased my RPM by changing down a gear and it cleared up. I can easily duplicate this scenario.
A couple of extra things. I was distracted by a funny movie on TV.
Firstly it is not a good idea to engage the aircon system over 2000RPM. It will work obviously but this creates a huge mechanical and electrical load. Now I am sure you are nowhere near the upper limit but this summer we had a couple of compressor blow ups.
The other item to remember is "Electrical Load". The electrical system of the 964 can supply around 75 amps and retain voltage. Please remember that with the aircon running you have a very high electrical load from the condenser fan, LH Blower fan and the electro-mechanical clutch. Add to that normal electrical needs, plus in the hot weather the oil cooler fan and the brake hydraulic pump (intermittant). Now add to that headlights, or the stereo running full bore and you have a high electrical load. Now if the rear blower fan also cranks up. Well I think you get the picture. The DME is "VERY" senstive to low voltage. If the voltage drops low enough it will switch to "Emergency Mode" and your C4 will run like crap.
Seems to me, well a possibility that you may have an excess electrical load, maybe being caused by a bad compressor or even the condenser fan.
I think you will have to eliminate the elctrical items, starting with the aircon related units from the picture one by one,
Ciao,
Adrian
911C4
PS: A similar thing happened to me in a tunnel. I had everything burning and turning except lights and aircon. I switched on the headlights as I entered the tunnel and then activated the aircon (it was hot in the tunnel) and suddenly I had a loss of power and it ran like crap. I somehow knew what it was and increased my RPM by changing down a gear and it cleared up. I can easily duplicate this scenario.
12-31-2001, 05:39 PM
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Adrian:
You mean my DME brain is not the orirginal one for a 1990 USA C4 Cab ? #0261-200-450 (911-618-124-04).
Here is what I did:
Took negative battery terminal off.
Waited 20 minutes.
Took DME brain connector off, inspected pins. All bright and clean as I had cleaned them yesterday, none bent.
Hooked the "central informer" back up.
Hooked the DMe brain back up.
Reconnected the negative battery terminal.
Results: Still intermittent XMAS tree effects. Also still always ON airbag and seat belt lights.
On a aside: How can I tell if the ignition coils are not intermittently openening up ? I lose sudden voltage to all 12 plugs at once (intermittently at idle and while driving).
Take care,
Patrick
You mean my DME brain is not the orirginal one for a 1990 USA C4 Cab ? #0261-200-450 (911-618-124-04).
Here is what I did:
Took negative battery terminal off.
Waited 20 minutes.
Took DME brain connector off, inspected pins. All bright and clean as I had cleaned them yesterday, none bent.
Hooked the "central informer" back up.
Hooked the DMe brain back up.
Reconnected the negative battery terminal.
Results: Still intermittent XMAS tree effects. Also still always ON airbag and seat belt lights.
On a aside: How can I tell if the ignition coils are not intermittently openening up ? I lose sudden voltage to all 12 plugs at once (intermittently at idle and while driving).
Take care,
Patrick
12-31-2001, 07:54 PM
#28
Burning Brakes
Thread Starter
Patrick,
Don't know if you picked up on my DME part number in the above post. It is 964 618 124 00. This is out of my 1990 C4 Cab (USA). California Emissions.
Adrian,
Thanks for the areas to look at. I will check out the A/C control unit and so on. I don't think that any of the A/C parts are culprit as many reportedly (By PO/receipts) were replaced just 8 months ago. No unusula noises from compressor, condensor, fan, etc... The one thing I have not looked at is the actual controls. I'll get a part number off the thing and report back. The A/C blows freezing cold. Granted it is a little nippy out anyway, but, my previous P-Car had a real weak A/C system(1986). Didn't matter what you did to it. It was marginal at best. I can see how voltage could be an issue, but, I didn't have lights on or stereo or basically anything else other than turning A/C on. Now I know that's a significant load, but, the alternator puts out 75 amps right? Iguess I might just turn on a TON of stuff and see what the reading is from the alternator. Could be that it checks out O.K. when not loaded much and takes a sh** when a load like that comes on.
I did the test you describe above and the RPM's do exactly as you indicate. If I have the car idling and turn the A/C on the RPM's drop for a split second then surge to about 800-900 and sit there even when I turn the fan speed on 4. Now with it on 4 you CAN NOT touch the gas or the engine will chug and die. If on any other setting on the fan dial it will rev like normal and settle back in to around 800-900.
BTW - what is LH Blower? Left Hand?
THanks again.
Don't know if you picked up on my DME part number in the above post. It is 964 618 124 00. This is out of my 1990 C4 Cab (USA). California Emissions.
Adrian,
Thanks for the areas to look at. I will check out the A/C control unit and so on. I don't think that any of the A/C parts are culprit as many reportedly (By PO/receipts) were replaced just 8 months ago. No unusula noises from compressor, condensor, fan, etc... The one thing I have not looked at is the actual controls. I'll get a part number off the thing and report back. The A/C blows freezing cold. Granted it is a little nippy out anyway, but, my previous P-Car had a real weak A/C system(1986). Didn't matter what you did to it. It was marginal at best. I can see how voltage could be an issue, but, I didn't have lights on or stereo or basically anything else other than turning A/C on. Now I know that's a significant load, but, the alternator puts out 75 amps right? Iguess I might just turn on a TON of stuff and see what the reading is from the alternator. Could be that it checks out O.K. when not loaded much and takes a sh** when a load like that comes on.
I did the test you describe above and the RPM's do exactly as you indicate. If I have the car idling and turn the A/C on the RPM's drop for a split second then surge to about 800-900 and sit there even when I turn the fan speed on 4. Now with it on 4 you CAN NOT touch the gas or the engine will chug and die. If on any other setting on the fan dial it will rev like normal and settle back in to around 800-900.
BTW - what is LH Blower? Left Hand?
THanks again.
12-31-2001, 07:57 PM
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Hey Slant,
You can easily check what's happening with your condenser fan:
-When you turn the AC on, the condenser fan should start in slow-speed. You can verify this by listening in the left-front corner of the car. Or, by feeling for air blowing out of the horizontal grill in the left-front corner of the car.
-As you bring your interior fan to the 3 position, and the car starts to run crappy, check again to see if the condenser fan might have kicked into fast-speed.
I just tried this on my own car, and the condenser fan doesn't kick into fan-speed as the interior fan speed is increased. To be honest, I don't know what exactly it takes to cause the condenser fan to start in fast-speed. I do know it receives its start signal from a 3-level freon pressure switch, so I'm guessing it starts in fast-speed at a certain load on the AC system?
You can easily check what's happening with your condenser fan:
-When you turn the AC on, the condenser fan should start in slow-speed. You can verify this by listening in the left-front corner of the car. Or, by feeling for air blowing out of the horizontal grill in the left-front corner of the car.
-As you bring your interior fan to the 3 position, and the car starts to run crappy, check again to see if the condenser fan might have kicked into fast-speed.
I just tried this on my own car, and the condenser fan doesn't kick into fan-speed as the interior fan speed is increased. To be honest, I don't know what exactly it takes to cause the condenser fan to start in fast-speed. I do know it receives its start signal from a 3-level freon pressure switch, so I'm guessing it starts in fast-speed at a certain load on the AC system?
12-31-2001, 08:03 PM
#30
Burning Brakes
Thread Starter
Randall,
I did that the other day too. The condensor fan runs as you describe. As soon as you turn the A/C on the fan kicks on. I was not particularly looking for a higher fan speed, so, I did not pay attention to that. The fan does run without any unusual noise or anything like that.
I did that the other day too. The condensor fan runs as you describe. As soon as you turn the A/C on the fan kicks on. I was not particularly looking for a higher fan speed, so, I did not pay attention to that. The fan does run without any unusual noise or anything like that.