andrew911

Excellent. My only thing is I only have a PSI gauge....so I'll have to guess how much to let out to make room for the 4 oz cannister of oil/other stuff. It was reading maybe 30 PSI yesterday vs. the recommended 16 PSI max per this site. I'll have to guesstimate...any idea of what PSI would be at 4 oz low? That would get me there because I'd just bleed the system to that number, and then add the 4 oz PAG can...


I guess eventually I'll have the system checked with the A/C machine my mechanic has- I took the shortcut of merely adding freon, but won't make the same mistake again of putting in the freon-only stuff! Next time, pre-mix will be all I buy and I'll be sure not to overcharge!

Thanks- and if you have any guesstimate of 4 oz low PSI reading, that would be helpful!

Andrew

Randall G.

Hey Andrew,

Not sure of how much to bleed--I'm guessing, just like yourself. I would drop it down to (say) 12 psi, as you'll still be in the acceptable band. If the pressure goes above 16 psi after adding the oil can, you'll have to dump some more.

The 16 psi is actually the high-end of the acceptable band. At (for example) 25C, the band is about 0.6 bar (8.7 PSI) to 1.1 bar (15.9 PSI). The band shifts up after 25C.

I think you know that the pressure readings should be taken with the compressor running.

Please let us know how things turn out.

andrew911

Randall- thanks! I have been checking with the compressor on - and yesterday was pretty hot which maybe got me one or two more PSI in the acceptible range so it wasn't as overfilled as it seems maybe only 47% over

You've been a great help- hopefully the store has the 4oz PAG oil cannister I need and I'll get this straight. I'm going to call them now to make sure.

I'll report back after tonight (assuming I can get the stuff)
Andrew

andrew911

Well, I got the PAG cannister. I went to release some pressure, and it's too much oily stuff shooting out....very messy. I'm going to admit defeat and get the car to the mechanic. My question is, will my system be damaged by leaving the car unused for a week or so, or do I need to get the pressure lowered ASAP??? Is the damage done mostly when the A/C is being used and the pressure is built up? (I assume the pressure isn't as high when the system is not in use....)

Thanks!

Randall G.

As long as you don't run the A/C, I think you'll be fine. Wonder how Ben lowered his system pressure without making an unmanageable mess? Must confess, I've never had to lower the pressure in my system, so don't really know how to go about lowering it neatly (without professional tools). Though, I suppose you could hook up the charge hose, sans can-tap-valve (which has an internal check valve to prevent back-flow), and direct the hose into a suitable container. If the can-tap isn't integral to your hose, that is (some are, some aren't).

Sorry to hear you'll need to take your car to your mechanic, but suppose it's for the better, make sure you have everything in order. At least you got cold air long enough to know your system still works.

andrew911

You're right...at least I know the system works, and it held the stuff overnight I did try bleeding it through the base where the cannister would normally go by attaching it and squeezing the trigger. No luck. Then I stood back and pressed the ball with a screwdriver, which made a mess in about 0.4 seconds.

Obviously not the right way to do it. I had too much pressure to let out, and even though its 134, it can't be that good for the surroundings not to mention it getting all over the car and my hand. I then washed my hands well, and sponged the car bumper and called it a night. The interior of the car was nice and cold for the few minutes it was on...

I really need the mechanics machine to lower the pressure and get the oil ratio right. For the record, now that I know how to do this, I will try it again with the proper freon/oil mixture next year, and I'll be sure to not overfill. One question though- I most likely wont need a full can next season or whenever I need to do this again- I have a trigger-style mechanism whereby the cannister screws onto the bottom. Do I just top off the system and leave the cannister attached to the trigger until the next year? There are no clear instructions with my unit or on the Interdynamics web site. Would the freon actually hold that long in the trigger-holder? What do you do with the cannister when its still 1/2 full- do you just leave it attached?

This is what I have:

http://www.id-usa.com/product.asp?CID=27&PID=45

Randall G.

Did you try to release the pressure with the compressor off? If so, yup, the low-side pressure is much higher than when the compressor is running. My low-side is at least 80 psi with the compressor off, as compared to 16 psi when it's running.

I'm guessing your charging trigger has an integral check valve, which prevents back-flow. You got no flow, right?

>Do I just top off the system and leave the cannister attached to the trigger until the next year?

I don't really know, I'm new at this charge-it-yourself stuff, too. You're right, the instructions have zero guidance on what to do if your system's full before the can is used up (in my case, I simply disconnected the can when I got the pressure I wanted). Or, what to do with left over gas. I imagine you should get a reading on your pressure gauge, if there's still pressure left in the can. If there's pressure left next year, great, you can use it up. If not, cans of R-134a are cheap.

I left the hose/gauge with quick connect shut-off attached to the can I used (even those it's empty). The empty can does a good job of keeping dirt out of the can-tap-valve. I put the other end in a baggie.

andrew911

Randall- I was releasing the pressure after the A/C was on for maybe 2 minutes. I was hoping the pressure would be less when it's off, thus doing no damage due to overcharging if not used...I guess the pressure is lower on the "high pressure" chamber/line when not used...I would imagine that's the side that would get damaged, or blow o-rings if the system is run with over charging. (I'm learning about the A/C systems- if this is the right anaology).

Yes, I got no flow when I pulled the charger trigger with no cannister attached. I thought there was most likely an internal check valve, especially as the instructions don't tell you not to pull the trigger when merely checking charge level- there would probably need to be a warning otherwise, as you're supposed to initially check pressure with no cannister attached...they'd be a lot of people squeezing that trigger by accident or on purpose getting a surprise otherwise with no cannister attached

By the way, after charging my system (or overcharging technically speaking), I thought there was nothing left in the 14 oz can & unscrewed it...well, there was freon left, which went spritzing out. It startled me, but no harm done. Just expect there to be charge left even after you think you used the whole can- make sure there aren't kids/dogs etc. around when you unscrew the spent cannister just in case.

I'll let you know (and anyone else who's reading the thread) how I make out once I can get to a place to get my charge and oil/freon mixture corrected!

Andrew

Carrera Mike

Randall, let me see if I understand you corectly, are you saying that if I do this relay jumper mod, the fan will run continously when the a/c is on, or only when the condenser get's hot(where it used to trigger the fan to go in slow speed, and off course the high speed)?

Also, when I do the jumper test on the relay plug between 30 and 87c(slow speed), the fan don't turn. Only when I jumper 30 and 87 is when the fan turn at high speed, does this mean that my fan resistor is dead?

thanks much

Randall G.

Hey Mike,

The condenser fan isn't like the oil cooler fan, which turns on when the oil reaches a certain temperature. The condenser fan runs continuously in slow-speed, whenever the A/C is on. It switches to fast-speed if system load drives high-side pressure high enough.

Terminal #1 (85) is the "start-signal" for fast-speed, terminal #6 (85c) is slow-speed. Terminal #8 (86) is 12V "control" power. All terminal #6 or #1 do for a "start-signal" is provide a current path from #8, through their respective coil, thus closing their associated contact between 30 and either 87c or 87. Otherwise, there's no current path, the associated coil isn't energized, and the associated contact remains open.

By jumping #1 and #6, the relay sees a "start-signal" for both slow and fast-speed. But, since current always takes the path of least resistance, current will only flow through 87--it's connected directly to the fan. 87c, on the other hand, goes through the notorious ballast resistor. Which, in our case, is basically an open circuit, anyway.

So, yes, with the #1/#6 jumper in place, your condenser fan will run continuously in fast-speed, whenever the A/C is running. That said, you may prefer to replace the ballast resistor, to restore slow-speed operation.

>Also, when I do the jumper test on the relay plug between 30 and 87c(slow speed), the fan don't turn. Only when I jumper 30 and 87 is when the fan turn at high speed, does this mean that my fan resistor is dead

Yup, it looks like it's dead. Thus, no way for 12V from 87c to reach the fan. You can double verify the resistor is dead by measuring resistance between terminals #5 & #7. It should be in the range of 1 ohm. If you get something like 30kohms, it's toast.

Hope this helps!

Carrera Mike

Randall, Thanks you for the info. I learned something new today. I will verify the the resistance. I think it's toast, 'cause like you said, I was getting like 3Kohms last night.

I ordered a new resistor from Pelican and won't get here till Tuesday. So for now I shunted terminals 1 & 6 and it sure enough, fan runs at high speed everytime I turn on the a/c. That will be my temp fix 'till I get the parts.

Just when I thought that my a/c was running normal. Now I think I know what 'causing the o-ring blow by I keep getting on the connection of the big hose to the condenser, THE HEAT! Since the fan wasn't running normally, I think that the o-ring was melting and keep letting the freon or R-132a out.

Thanks much/Appreciate all the help.

Mike

Carrera Mike

Randall,

Here's what I did, picture below, I sodered a jumper between 87 and 87C. I saw an entry in the oil heat thread that one member was suggesting putting the jumper between 85 and 85C. Is one better than the other on current load?

Also, this is ok for the oil fan side too right??

Thanks

Randall G.

Hey Mike,

Yup, you can place the jumper between 87 & 87C, but it's going to carry a lot more current than a jumper between 85 & 85C. 87/87C supply direct current to the fan--in the neighborhood of 10-15A, fused at 30A. 85 & 85C carry a control (low power) current, about 0.15A.

I added my jumper externally, using a short 1.7 ohm resistor, with the wires on either end stuffed into the relay slots--I'll post a pic later today.

The same mod will work for the oil cooler fan. Though, you may prefer the fast-speed switch (installation described on P-car.com), instead.

Talk to you soon...

Carrera Mike

Randall,

I just got back from a grocery run. I actually volunteered to pick up some stuff for the wife just to test this project The A/C fan run as soon as I turned it on like you said. The oil cooler fan, I have to wait for that. It started running(in fast speed of course) when the temp gauge at 9 oclock.

I'd like to do what you did, just the resistor. What stripes color does 1.7ohms has? I have a bunch here(from rc cars). If that external jumper is better, current load wise, I'd like to use that instead of what I did bridging 87 and 87C. Did you jump 85 and 85C? Picture will be great. Thanks much man.

Randall G.

Hey Mike,

Here's a picture of my external jumper:



I used an external jumper partially because I didn't want to modify a good relay, mainly because I was too lazy to get out the solder iron. Oh, and I misspoke earlier--it's a 1.9 ohm resistor, not 1.7 ohms.

With the A/C on, condenser fan running, there's 0.262V across the resistor. So, 0.14A. Which is about what I expected, considering that there is a 75 ohm resistor between 86 & 85/85c, internal to the relay >> 12V/75 ohms = 0.16A. The 1.9 ohm resistor does little to affect the series resistance.

You don't have to use a (low-value) resistor like I did, if you don't have one. You can simply use an insulated wire. Since I had it, I used the resistor. For a few reasons. Because the majority of the exposed area was insulator, and not "hot" wire. The wire ends were nice and rigid, making it easy to shove 'em in the relay slots. And, if the jumper wire was to (for some strange reason) ever connect 12V directly to ground, there would be some limit on the current.

I imagine you can also jumper 85/85c internal to relay (similar to what you did for 87/87c). Haven't tried it myself.

As you know, this jumper won't make the oil cooler fan run continuously. But, it will run the fan in fast-speed, whenever the relay receives a signal to start the fan in slow-speed. As you saw when your oil temperature got to about 9:00.

Incidentally, if you're going to leave your relay modified, there's no point in replacing the 0.450 ohm ballast resistor. As I described earlier, the jumper will cause the resistor to be shunted. Conversely, if you replace the ballast resistor, and want slow-speed functional, you'll need to remove the jumper. But, I suspect you know this already.

Talk to you soon....