Ac runs warm and compressor oil leaking.
09-07-2014, 07:18 PM
#1
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Thread Starter
Ac runs warm and compressor oil leaking.
My ac runs cold for awhile then it gradually runs warm in front while the rear stays cold. Some time it runs cold until shut off. Heater valve is working so it's not that. I've been reading about this problem but found nothing definite yet.
Once awhile, after warming up the car with ac on then shut down, the oil from compressor area leak on to the floor. It leaks a lot yesterday after idling for 20 min.
Any idea on why compressor oil is leaking out intermittently? Tia.
Once awhile, after warming up the car with ac on then shut down, the oil from compressor area leak on to the floor. It leaks a lot yesterday after idling for 20 min.
Any idea on why compressor oil is leaking out intermittently? Tia.
09-07-2014, 09:02 PM
#2
Burning Brakes
It probably means that your heater valve is not closing.
The A/C runs cold while the coolant is cool. Once the coolant heats up, it heats up the heater core, which overwhelms the A/C, i.e. warm air.
I'd check your heater valve first. About oil from the compressor... I defer to the experts. Good luck!
The A/C runs cold while the coolant is cool. Once the coolant heats up, it heats up the heater core, which overwhelms the A/C, i.e. warm air.
I'd check your heater valve first. About oil from the compressor... I defer to the experts. Good luck!
09-07-2014, 10:01 PM
#3
Rennlist Member
Thread Starter
If I run the fan or fresh air vent then the air is cool only when the AC is on it's hot. AC sometimes runs cold for 40 min drive but not other time. Vacuum tested the heater valve so it's closed. I suspect it's electrical somewhere but still searching.
The compressor oil leak because of over pressure in expansion valve? Tia.
The compressor oil leak because of over pressure in expansion valve? Tia.
09-08-2014, 02:50 AM
#4
(they always tell me to not forget to check temp sensor connections)
generally The seals will hold considerable pressure before a leak.
However, of course you know, that the seals aren't supposed to leak anyway, and certainly not oil. If oil get out so does freon. If freon gets out then cooling gets intermittent at first then goes away. Often the compressor goes away without oil too.
The oil may not be the symptom, it may be the problem.
It may be possible that it's a good old fashioned failed seal. especially if it's coming from behind the clutch. Either way, an oil leak enough to make a puddle on the floor, is probably letting pressure leak as well. That is, letting freon leak.
second issue may be a cooling fan. You didn't mention. When on a 40 minute trip you should have plenty of airflow.
Sitting at idle for a while without the cooling fan will cause pressures and temps to go up.
And yes certainly a clogged forward txv may be suspect as well. But they don't often unclog, then clog again.
May be low on freon (from a leaky seal), may have a leaky seal loosing oil and freon. And maybe due to high pressure brought on by a inoperative fan or blocked txv.
Out of all of this, my concern would be the puddle of compressor oil...they don't hold much, and without it...well you know...It wont be long.
Most shops will have a halon type leak detector...a sniffer. If in fact the front seal is going bad, they may be able to "sniff it out". A seal replacement is somewhat cheaper than letting a compressor run out of oil.
Of course a gauge manifold is the AC tech's best friend. If it's running, a gauge set may tell the tale in just a minute or two.
sometimes a quick check of compressor operation, is simply to check for bubbles in the receiver dryer sight glass. No, bubbles aren't supposed to be there, but most systems have one or two here and there. If ya see some moving past the sight glass, at least the compressor is moving freon. Not 100% accurate, but sometimes you can at least tell if the compressor is moving freon.
a set of gauges, a sniffer, the sightglass and the fan operation may all be clues.
But in the end...oil's not supposed to get out.
Anyway, hope that helps at least a little. Maybe you can get a look at a couple of other things now and home in on the issue a little better.
generally The seals will hold considerable pressure before a leak.
However, of course you know, that the seals aren't supposed to leak anyway, and certainly not oil. If oil get out so does freon. If freon gets out then cooling gets intermittent at first then goes away. Often the compressor goes away without oil too.
The oil may not be the symptom, it may be the problem.
It may be possible that it's a good old fashioned failed seal. especially if it's coming from behind the clutch. Either way, an oil leak enough to make a puddle on the floor, is probably letting pressure leak as well. That is, letting freon leak.
second issue may be a cooling fan. You didn't mention. When on a 40 minute trip you should have plenty of airflow.
Sitting at idle for a while without the cooling fan will cause pressures and temps to go up.
And yes certainly a clogged forward txv may be suspect as well. But they don't often unclog, then clog again.
May be low on freon (from a leaky seal), may have a leaky seal loosing oil and freon. And maybe due to high pressure brought on by a inoperative fan or blocked txv.
Out of all of this, my concern would be the puddle of compressor oil...they don't hold much, and without it...well you know...It wont be long.
Most shops will have a halon type leak detector...a sniffer. If in fact the front seal is going bad, they may be able to "sniff it out". A seal replacement is somewhat cheaper than letting a compressor run out of oil.
Of course a gauge manifold is the AC tech's best friend. If it's running, a gauge set may tell the tale in just a minute or two.
sometimes a quick check of compressor operation, is simply to check for bubbles in the receiver dryer sight glass. No, bubbles aren't supposed to be there, but most systems have one or two here and there. If ya see some moving past the sight glass, at least the compressor is moving freon. Not 100% accurate, but sometimes you can at least tell if the compressor is moving freon.
a set of gauges, a sniffer, the sightglass and the fan operation may all be clues.
But in the end...oil's not supposed to get out.
Anyway, hope that helps at least a little. Maybe you can get a look at a couple of other things now and home in on the issue a little better.
09-08-2014, 04:54 PM
#5
Rennlist Member
Thread Starter
ok, ran the AC again and checked these items:
Sight glass is solid yellow with compressor either on or off so it must be covered with oil and water? I can't tell bubbles or not- Forgot to look at this before. What caused this solid yellow eyesight?
System is still pressurized but not nitrogen- I push the valve in on high side (by sight glass) and only air comes out but not cold nitrogen air. Where is the low side charge valve?
Low pressure side is 90F and high pressure side is 130F- checked by the dryer with IR thermometer so expansion valve is working? Inside vent is 60F, ambient is 78F so there's some cooling.
No compressor oil leak after I shut down, unlike Sat. If seals were weak, I would loose all pressure by now? I hate to rebuild compressor ($120), replace dryer, and recharge R12 if It's not the cause.
Can't check system pressure because my 134A gauge won't connect to the R12 fitting on car. I might buy the 134A adaptor kit and use the 134A gauge to check and add 134a freon to the car. I am planning to buy R12 to recharge if I can find a set of R12 gauge so I don't have to mess with replacing all the O-rings.
Thanks for the help. This 928 is a project on low priority so I am working on it whenever I can so my diagnose skills is not focused.
Sight glass is solid yellow with compressor either on or off so it must be covered with oil and water? I can't tell bubbles or not- Forgot to look at this before. What caused this solid yellow eyesight?
System is still pressurized but not nitrogen- I push the valve in on high side (by sight glass) and only air comes out but not cold nitrogen air. Where is the low side charge valve?
Low pressure side is 90F and high pressure side is 130F- checked by the dryer with IR thermometer so expansion valve is working? Inside vent is 60F, ambient is 78F so there's some cooling.
No compressor oil leak after I shut down, unlike Sat. If seals were weak, I would loose all pressure by now? I hate to rebuild compressor ($120), replace dryer, and recharge R12 if It's not the cause.
Can't check system pressure because my 134A gauge won't connect to the R12 fitting on car. I might buy the 134A adaptor kit and use the 134A gauge to check and add 134a freon to the car. I am planning to buy R12 to recharge if I can find a set of R12 gauge so I don't have to mess with replacing all the O-rings.
Thanks for the help. This 928 is a project on low priority so I am working on it whenever I can so my diagnose skills is not focused.
09-08-2014, 07:46 PM
#6
Rennlist Member
Solid yellow indicates a dye in the system. Before releasing anymore freon into the air get some guages (harbor freight) and check pressures. Low side (if same as '86) will be found on passenger side, front, underneath intake ducting.
09-11-2014, 08:39 AM
#7
Sorry to leave ya hangin' I got on another air conditioning thread and thought it was you. Sorry.
The exercise here was to see if the ac system is working ok, and if the oil leak is really compressor oil, and what may be causing the leak of oil and if so to fix it.
we wanted to know if the freon system is operating out under the hood in order to separate it from an airflow issue. (You already separated it from a heater valve issue). Sometimes the AC system can be on and running out under the hood, making good cold air, but the heater valve or some airflow issue in the cabin can divert the cold air and while the system is actually working out font, the cabin air is warm.
That's why I wanted to first find out if it's even working. Measuring the line temp on the cold side (under the passenger side air intake tube, and the hot side, (by the dryer is fine), will tell us if the system is actually working. A quick look at the sight glass can also tell if freon is moving around. And if you can tell the difference between the clutch and pulley, then looking at the compressor clutch are all indicators (temps are best) as to whether the system is "on and working".
If it is, then the problem is probably in the HVAC control system. If not, then it may be in the freon system itself or the temp sensors not turning it on.
if it's running but not cooling very well, it could be low freon, or low airflow through the front radiator (condenser). Indicating a fan issue.
As for the oil, the oil isn't supposed to come out. period. if it is, something is wrong. could be a shaft seal and "most often" that's the case. once in a while it's a loose connection, but not often.
but before we go off down the wrong road, you would want to make sure the leaking fluid is oil, and you'd want to make sure it's actually coming from the AC compressor. yellow dye would be a clue here. Compressor oil is also very "fine" oil. it wouldn't be thick like engine oil. And if you can actually see it, it would "most often" come from the back side of the AC compressor pulley.
Since a freon molecule is much smaller than an oil molecule, you can be sure that if there is an oil leak, there is a freon leak there as well. Unless there is a crack in the very bottom of the compressor letting out oil, but as soon as it has leaked out, freon will follow.
If it's a shaft seal, the freon and oil will leak out together.
This will cause low freon level and the AC to run inefficiently, until it get's low enough to hit the pressure switch, then it wont come on again..
sometimes thee are two issues at once. this is a pain in the *** to troubleshoot. the ac system may be failing due to a leak, and the HVAC system may be blocking some of your cooling air in the front vents but not the back.
it's possible for a dual evaporator system to have one expansion valve clogged and the other working, but it's not usual for an expansion valve to become clogged, and then work, then become clogged, then work, etc.
Gauges will help.
Knowing is there is a low freon issue will help.
Making sure the oil is AC oil will help.
knowing is the ac system is cooling on the outside (when it's warm inside) will help as well.
The exercise here was to see if the ac system is working ok, and if the oil leak is really compressor oil, and what may be causing the leak of oil and if so to fix it.
we wanted to know if the freon system is operating out under the hood in order to separate it from an airflow issue. (You already separated it from a heater valve issue). Sometimes the AC system can be on and running out under the hood, making good cold air, but the heater valve or some airflow issue in the cabin can divert the cold air and while the system is actually working out font, the cabin air is warm.
That's why I wanted to first find out if it's even working. Measuring the line temp on the cold side (under the passenger side air intake tube, and the hot side, (by the dryer is fine), will tell us if the system is actually working. A quick look at the sight glass can also tell if freon is moving around. And if you can tell the difference between the clutch and pulley, then looking at the compressor clutch are all indicators (temps are best) as to whether the system is "on and working".
If it is, then the problem is probably in the HVAC control system. If not, then it may be in the freon system itself or the temp sensors not turning it on.
if it's running but not cooling very well, it could be low freon, or low airflow through the front radiator (condenser). Indicating a fan issue.
As for the oil, the oil isn't supposed to come out. period. if it is, something is wrong. could be a shaft seal and "most often" that's the case. once in a while it's a loose connection, but not often.
but before we go off down the wrong road, you would want to make sure the leaking fluid is oil, and you'd want to make sure it's actually coming from the AC compressor. yellow dye would be a clue here. Compressor oil is also very "fine" oil. it wouldn't be thick like engine oil. And if you can actually see it, it would "most often" come from the back side of the AC compressor pulley.
Since a freon molecule is much smaller than an oil molecule, you can be sure that if there is an oil leak, there is a freon leak there as well. Unless there is a crack in the very bottom of the compressor letting out oil, but as soon as it has leaked out, freon will follow.
If it's a shaft seal, the freon and oil will leak out together.
This will cause low freon level and the AC to run inefficiently, until it get's low enough to hit the pressure switch, then it wont come on again..
sometimes thee are two issues at once. this is a pain in the *** to troubleshoot. the ac system may be failing due to a leak, and the HVAC system may be blocking some of your cooling air in the front vents but not the back.
it's possible for a dual evaporator system to have one expansion valve clogged and the other working, but it's not usual for an expansion valve to become clogged, and then work, then become clogged, then work, etc.
Gauges will help.
Knowing is there is a low freon issue will help.
Making sure the oil is AC oil will help.
knowing is the ac system is cooling on the outside (when it's warm inside) will help as well.
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09-12-2014, 02:42 AM
#8
Rennlist Member
Thread Starter
Thanks for the detail diagnostic The Patman. I am also following Kevin in Atlanta's AC thread.
Just for the h3ll of it, I took the car out today for a 80 mile trip in 90F heat wave with most of it 80 mph to see whether something will break just so it's easier to fix but nothing.
Ac is cool enough at 1st fan speed to keep me comfy, not cold so I know freon is low. At least it was not blowing heat like it did before. AC was colder a month ago but we didn't have heat wave back then. Still looking for a R12 gauge to check pressure since I have R134 gauge.
Oil color is like cooking oil but not yellow like the dye in the sight glass and seems to leak by compressor pulley. Sight glass is solid yellow regardless of whether AC is on/off so I can't see bubbles indicating low freon. I left a 3" puddle on the floor for marking 4 days ago and it seems to evaporated with a very slight oil residue left on my epoxy sealed floor. My engine oil is dino and brown (time for change) and BMW coolant is blue for aluminum engines, definitely not brake fluid- is there another coolant or oil around the compressor?
Car parked for 8hrs since I came back today with no trace of oil leaks. I know both elect fan works, clutch on compressor works (rpm changes when AC engage/disengage), and I can see it kick in.
I guess Esther/ mineral oil for compressor is not very oily and may evaporate which explains why it leaks from the seal shaft but as you said it's unlikely and it either leaks or not. At least it's still working now just hoping it's not blowing heat when I really need AC again. I am suspecting electrical / sensor but which one? If I was missing the external temp sensor by the driver side headlight then it wouldn't run hot/ cold intermittently ? Thanks.
Just for the h3ll of it, I took the car out today for a 80 mile trip in 90F heat wave with most of it 80 mph to see whether something will break just so it's easier to fix but nothing.
Ac is cool enough at 1st fan speed to keep me comfy, not cold so I know freon is low. At least it was not blowing heat like it did before. AC was colder a month ago but we didn't have heat wave back then. Still looking for a R12 gauge to check pressure since I have R134 gauge.
Oil color is like cooking oil but not yellow like the dye in the sight glass and seems to leak by compressor pulley. Sight glass is solid yellow regardless of whether AC is on/off so I can't see bubbles indicating low freon. I left a 3" puddle on the floor for marking 4 days ago and it seems to evaporated with a very slight oil residue left on my epoxy sealed floor. My engine oil is dino and brown (time for change) and BMW coolant is blue for aluminum engines, definitely not brake fluid- is there another coolant or oil around the compressor?
Car parked for 8hrs since I came back today with no trace of oil leaks. I know both elect fan works, clutch on compressor works (rpm changes when AC engage/disengage), and I can see it kick in.
I guess Esther/ mineral oil for compressor is not very oily and may evaporate which explains why it leaks from the seal shaft but as you said it's unlikely and it either leaks or not. At least it's still working now just hoping it's not blowing heat when I really need AC again. I am suspecting electrical / sensor but which one? If I was missing the external temp sensor by the driver side headlight then it wouldn't run hot/ cold intermittently ? Thanks.
Last edited by Bmw635; 09-12-2014 at 03:18 AM.
09-12-2014, 02:49 AM
#9
Archive Gatekeeper
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Rennlist Member
Peter, I have a good set of R12 gauges, holler and I can leave 'em on the front porch.
09-12-2014, 03:08 AM
#10
Rennlist Member
Thread Starter
In that case let me get couple R12 can tomorrow and swing by 10am Sat to get the gauge that way I can recharge too. I still need to get it on the ramp to find the low side connection. Thanks Rob.
09-12-2014, 11:06 AM
#11
Rennlist Member
.02: It seems you know you have a leak at the compressor. It would seem you would be wasting the R12 at this point. Having followed these threads for years, replacing A/C parts piecemeal is also wasting time and $$. I'm not saying the whole thing has to be dismantled and replaced, but . . . .
Also in post 5 you seem to be saying you would use 134 gauges on an r12 system if you can find the adaptors. I don't know if the 134 set is used or brand new, but this is a plan for contamination and disaster. Besides your system, no shop will risk their equipment (if they know) on a system that has had any chance of a mix of 134 and r12, which would happen if your 134 gauges are used, and I assume they are. There is a reason the oriface is system specific and it is to prevent contamination.
I assume there is no r12 shop available. If you are going to keep the r12, and many recommend that, you need to bite the bullet and get r12 equipment. That is hard to find and can be expensive. Once you start replacing seals and valves, you might find yourself longing to switch to 134 so professionals can fix it, either route cam be expensive. Just trying to help illuminate the options available to you.
Also in post 5 you seem to be saying you would use 134 gauges on an r12 system if you can find the adaptors. I don't know if the 134 set is used or brand new, but this is a plan for contamination and disaster. Besides your system, no shop will risk their equipment (if they know) on a system that has had any chance of a mix of 134 and r12, which would happen if your 134 gauges are used, and I assume they are. There is a reason the oriface is system specific and it is to prevent contamination.
I assume there is no r12 shop available. If you are going to keep the r12, and many recommend that, you need to bite the bullet and get r12 equipment. That is hard to find and can be expensive. Once you start replacing seals and valves, you might find yourself longing to switch to 134 so professionals can fix it, either route cam be expensive. Just trying to help illuminate the options available to you.
09-12-2014, 11:26 AM
#12
Archive Gatekeeper
Rennlist Member
Rennlist Member
No need to put it on a ramp for the low side connection, it's (slightly) accessible from the top, on the passenger side about 6" below the 14 pin connector. It's actually part of the fitting at the end of the suction/low side return pipe from the evaporators:
Crappy picture warning, but a good indicator of how buried it is...
Here's a more exposed view, (on my GTS, which actually moved the connector up under the cowl), but it gives you an idea of where it's located on an S4..
Crappy picture warning, but a good indicator of how buried it is...
Here's a more exposed view, (on my GTS, which actually moved the connector up under the cowl), but it gives you an idea of where it's located on an S4..
09-12-2014, 12:54 PM
#13
Rennlist Member
Thread Starter
SteveG. Thanks for the precaution. The 134 gauge is mine and used so I'll keep it aside. I can get compressor rebuild for $120 but evac is an issue since every shop use 134 now. Given the high pressure I have left in system, shouldn't it be gone by now after couple weeks if it leaks?
Rob, is the shradervalve for low side by the red arrow in your 2nd pic? Thanks
Rob, is the shradervalve for low side by the red arrow in your 2nd pic? Thanks
09-12-2014, 01:12 PM
#15
Chronic Tool Dropper
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Couple red flags:
You mention putting R-134a into an R12 car. Don't do it without doing the full conversion. R-134a won't carry the mineral oil used in the R12 car, so the compressor will be damaged.
Most oil leaking from the bottom of the compressor is oil that leaked onto the top of the compressor and ran down. The cam covers are convenienly right above the compressor, for instance. If compressor oil is acyually leaking out, waste no time adding refrigerant until you pull the compressor and reseal/rebuild/replace it. Flush the system if you can, replace the drier and every system o-ring you can get to, and refill with the correct amount of oil.
The yellow sight glass that never shows bubbles means that there is a film of oil on the glass, and no liquid circulating from the condenser. So freon is low, so low that there isn't enough pressure to condense whatever freon is still in there.
-----
I'm going to speculate that auto AC systems are not a strong point for you. Because the costs of mistakes are high, it would be worth working with a competent AC person to fix the problems you have before they get too far out of hand. eg: Running with low freon means no oil is circulating. If that is compressor oil on the garage floor (very pale yellow oil with no dirt in it at all), the problem is more serious. When the compressor runs low on oil, it will seize, and bits of aluminum pistons and bores will be pushed out at least through the condenser, drier and associated plumbing. In severe cases the drier dessicant bag is torn, and the compressor debris plus the dessicant gets pushed through to the expansion valves. Sean R posted a thread a few weeks ago about how it was taking day$ to clean out a system following just a desicant bag rupture. Bottom line is you are on a very slippery slope, with a known pool full of cash-hungry alligators. Walk carefully.
You mention putting R-134a into an R12 car. Don't do it without doing the full conversion. R-134a won't carry the mineral oil used in the R12 car, so the compressor will be damaged.
Most oil leaking from the bottom of the compressor is oil that leaked onto the top of the compressor and ran down. The cam covers are convenienly right above the compressor, for instance. If compressor oil is acyually leaking out, waste no time adding refrigerant until you pull the compressor and reseal/rebuild/replace it. Flush the system if you can, replace the drier and every system o-ring you can get to, and refill with the correct amount of oil.
The yellow sight glass that never shows bubbles means that there is a film of oil on the glass, and no liquid circulating from the condenser. So freon is low, so low that there isn't enough pressure to condense whatever freon is still in there.
-----
I'm going to speculate that auto AC systems are not a strong point for you. Because the costs of mistakes are high, it would be worth working with a competent AC person to fix the problems you have before they get too far out of hand. eg: Running with low freon means no oil is circulating. If that is compressor oil on the garage floor (very pale yellow oil with no dirt in it at all), the problem is more serious. When the compressor runs low on oil, it will seize, and bits of aluminum pistons and bores will be pushed out at least through the condenser, drier and associated plumbing. In severe cases the drier dessicant bag is torn, and the compressor debris plus the dessicant gets pushed through to the expansion valves. Sean R posted a thread a few weeks ago about how it was taking day$ to clean out a system following just a desicant bag rupture. Bottom line is you are on a very slippery slope, with a known pool full of cash-hungry alligators. Walk carefully.