Ac runs warm and compressor oil leaking.
09-13-2014, 06:13 PM
#16
Rennlist Member
Thread Starter
Got the gauge on and it shows these # so I am stump.
Engine off: 120 psi on High, 0 on low.
Engine idle: 225 psi on high, 38 psi on low.
Engine 2000 rpm: 230psi on high, 15 psi on low.
Interior bower is cool with IR thermometer showing 60f and old red liquid thermometer at 80f, ambient air is 80f.
Ir thermometer read 125f on high side, 135f on low side. This is abnormal?
No compressor oil leak since couple days ago, even after 20 miles drive today or during the reading. Both aux fan ran low and high during this session.
Looks like pressure is normal, no leaks, but why is the air not cold? What other kind of oil could leak intermittently by the compressor that looks slight clear that's not coolant , engine oil? Tia.
After 5 hrs of this posting, the gauge on high and low setttled at 105 and 98 so looks like static pressure is ok.
Engine off: 120 psi on High, 0 on low.
Engine idle: 225 psi on high, 38 psi on low.
Engine 2000 rpm: 230psi on high, 15 psi on low.
Interior bower is cool with IR thermometer showing 60f and old red liquid thermometer at 80f, ambient air is 80f.
Ir thermometer read 125f on high side, 135f on low side. This is abnormal?
No compressor oil leak since couple days ago, even after 20 miles drive today or during the reading. Both aux fan ran low and high during this session.
Looks like pressure is normal, no leaks, but why is the air not cold? What other kind of oil could leak intermittently by the compressor that looks slight clear that's not coolant , engine oil? Tia.
After 5 hrs of this posting, the gauge on high and low setttled at 105 and 98 so looks like static pressure is ok.
Last edited by Bmw635; 09-13-2014 at 09:23 PM. Reason: addtional update
09-14-2014, 04:16 PM
#17
Mr. 5, sorry to leave ya hangin'. I tried to answer this twice this morning. The first time was long and detailed. (when your new ya gotta be detailed, cause one omission or one wrong word and ...well...anyway, it makes for long winded posts) so when I hit submit...it ask me to login again (timed out) and I lost it all!! Dammit! So I tried a second time, not as long and detailed, and hit submit and got a database error, and lost it all. But if a guy is hangin' out on a Sunday and needs a hand, i don't wanna leave him (or her) hangin'. Sooooo.
Static pressures (after you let it equalize) look like you have freon, or actually pressure. Pressure enough to make the switch. And indicate that you have plenty of freon. You should check static pressure before you start it.
80 and 80 would have looked ok.
running pressures look acceptable as well. at 80 ambient, r-12 might look more like 190 and 30, but if the compressor isn't running on and off constantly, your pressures aren't too bad. The reason I say "cutting on and off" is that a high pressure and a low pressure at the same time might indicate a partially closed orifice. If it's clogged, it would back up on the high side (from the blockage) making high pressures (250 - 275) and it would be like a clogged drinking straw on the other side of the orifice (expansion valve) and make for really low pressures (below 15 psi, and yeah your a bit low) if it gets too low the compressor will cut off cor a few seconds till it catches up and then run for a few seconds till it sucks it down again and repeat. It would be noticeable.
anyway, unless someone says different pressures aren't too bad.
the temps you measured are.
I think you may have not measured them in the right place. The evaporator in the cabin gets cold and it should be just above freezing. It's cold. If the line coming out of the cabin is cold (say 40-50 degrees) it's working pretty good. If it were possible to measure it right at the outlet of the evaporator itself, like I said, it would be nice if it's just above freezing. Anyway, the hot side will be often over a hundred degrees, and the cold side 35-60 depending on how far away from the evaporator you actually measure it. The closer the colder. you should use a measuring device that actually touches the line if possible, IR is OK but gets the temps of everything around it as well. Measuring at the inlet to the font condenser and the outlet of the evaporator is best. If it's cold you should get cold air. That simple. And if that line is getting that cold it will often have easily recognizable condensation on it...that may drip onto the floor...and leave a puddle.
If you are not getting a really cold line (pipe), then it may be an HVAC control issue. The mixer valve, the recirc door (flap under the glove box) or a temp sensor, especially the one out in the front fender well.
I say this now 'cause except for the oil thing, your system isn't perfect, but not so far out that ya shouldn't get some kinda cool air. (again provided it's not blocked and cycling on and off)
So it comes down to the oil leak, and the obvious issue of blowing "not cool" air in the cabin.
The oil isn't leaking now. Seals don't too often fix themselves. although the same guy who put in the dye coulda put in stop leak and miraculously it's doing something. Or ya ran out :-)
Unless you hear something different from one of the elders, I'd divert my attention to the HVAC controls at least to make sure the temp sensors and obvious dirverter doors are working.
Now after all of this. I will say that this all applies to a capilary tube single evaporator system. Thermal expansion valves and dual evaporators can complicate things a bit, as you could have flow through one part of the system and not the other.
look at this thing, especially the temp sensor in the wheel well part. its a five minute check. mine was corroded and i found my ac system was working, but was also getting warm air. Cleaned it and fixed the AC.
you've seen this I'm sure...
https://www.928gt.com/T-WallyHVAC.aspx
Static pressures (after you let it equalize) look like you have freon, or actually pressure. Pressure enough to make the switch. And indicate that you have plenty of freon. You should check static pressure before you start it.
80 and 80 would have looked ok.
running pressures look acceptable as well. at 80 ambient, r-12 might look more like 190 and 30, but if the compressor isn't running on and off constantly, your pressures aren't too bad. The reason I say "cutting on and off" is that a high pressure and a low pressure at the same time might indicate a partially closed orifice. If it's clogged, it would back up on the high side (from the blockage) making high pressures (250 - 275) and it would be like a clogged drinking straw on the other side of the orifice (expansion valve) and make for really low pressures (below 15 psi, and yeah your a bit low) if it gets too low the compressor will cut off cor a few seconds till it catches up and then run for a few seconds till it sucks it down again and repeat. It would be noticeable.
anyway, unless someone says different pressures aren't too bad.
the temps you measured are.
I think you may have not measured them in the right place. The evaporator in the cabin gets cold and it should be just above freezing. It's cold. If the line coming out of the cabin is cold (say 40-50 degrees) it's working pretty good. If it were possible to measure it right at the outlet of the evaporator itself, like I said, it would be nice if it's just above freezing. Anyway, the hot side will be often over a hundred degrees, and the cold side 35-60 depending on how far away from the evaporator you actually measure it. The closer the colder. you should use a measuring device that actually touches the line if possible, IR is OK but gets the temps of everything around it as well. Measuring at the inlet to the font condenser and the outlet of the evaporator is best. If it's cold you should get cold air. That simple. And if that line is getting that cold it will often have easily recognizable condensation on it...that may drip onto the floor...and leave a puddle.
If you are not getting a really cold line (pipe), then it may be an HVAC control issue. The mixer valve, the recirc door (flap under the glove box) or a temp sensor, especially the one out in the front fender well.
I say this now 'cause except for the oil thing, your system isn't perfect, but not so far out that ya shouldn't get some kinda cool air. (again provided it's not blocked and cycling on and off)
So it comes down to the oil leak, and the obvious issue of blowing "not cool" air in the cabin.
The oil isn't leaking now. Seals don't too often fix themselves. although the same guy who put in the dye coulda put in stop leak and miraculously it's doing something. Or ya ran out :-)
Unless you hear something different from one of the elders, I'd divert my attention to the HVAC controls at least to make sure the temp sensors and obvious dirverter doors are working.
Now after all of this. I will say that this all applies to a capilary tube single evaporator system. Thermal expansion valves and dual evaporators can complicate things a bit, as you could have flow through one part of the system and not the other.
look at this thing, especially the temp sensor in the wheel well part. its a five minute check. mine was corroded and i found my ac system was working, but was also getting warm air. Cleaned it and fixed the AC.
you've seen this I'm sure...
https://www.928gt.com/T-WallyHVAC.aspx
09-14-2014, 09:48 PM
#18
Rennlist Member
Thread Starter
Thanks for taking the time to help out a man in "heat", The Patman.
Yea, I am stump that's why I am looking for ideas. The AC was colder about 2 months ago when i went for lunch with couple BMW buddies to show off my 928. After coming out from lunch, the car was blowing very hot air so I shut off until we got back to one of the guy's house. Going home after this, I turned on the Ac and it blows normal.
I removed the stereo a month ago because its dead to clean up all the aftermarket wiring for amp and CD charger. After this cleanup, I noticed the air ir not as cold as before but still blowing cool air in the heat.
Only when I noticed the whatever oil leak that prompted me to start this ac thread. The first time it leaks was when I came back from a 100 mile trip with a 3" puddle so I chalked it up engine oil even though it didn't match. The 2nd time it leaks a 5"puddle with a 3"wide run 20" long down sloping garage thats why I started this thread.
At this time the evaporator is not condensing water puddle and the low side is supposed to be cold but its hotter the the high side which is weird. if i can figure out why the lowside is hot instead of cold it might give a clue since the expansion valve in front and rear seems to be OK. May be R12 pressure is low enough to not put out cold air but not enough to cycle the compressors?
I just recharged 134 in 5 other cars in June with no issue so i think I got the basics right. I'll check the temp sensor by driver side tonight just to rule it out 100%. Thx .
Yea, I am stump that's why I am looking for ideas. The AC was colder about 2 months ago when i went for lunch with couple BMW buddies to show off my 928. After coming out from lunch, the car was blowing very hot air so I shut off until we got back to one of the guy's house. Going home after this, I turned on the Ac and it blows normal.
I removed the stereo a month ago because its dead to clean up all the aftermarket wiring for amp and CD charger. After this cleanup, I noticed the air ir not as cold as before but still blowing cool air in the heat.
Only when I noticed the whatever oil leak that prompted me to start this ac thread. The first time it leaks was when I came back from a 100 mile trip with a 3" puddle so I chalked it up engine oil even though it didn't match. The 2nd time it leaks a 5"puddle with a 3"wide run 20" long down sloping garage thats why I started this thread.
At this time the evaporator is not condensing water puddle and the low side is supposed to be cold but its hotter the the high side which is weird. if i can figure out why the lowside is hot instead of cold it might give a clue since the expansion valve in front and rear seems to be OK. May be R12 pressure is low enough to not put out cold air but not enough to cycle the compressors?
I just recharged 134 in 5 other cars in June with no issue so i think I got the basics right. I'll check the temp sensor by driver side tonight just to rule it out 100%. Thx .
Last edited by Bmw635; 09-15-2014 at 01:44 AM.
09-14-2014, 10:06 PM
#19
Rennlist Member
Thread Starter
I guess a baking thermometer with dial is best to measure temp at the vent? I know the ir thermometer is hitting the plastic duct so its not accurate. Thx.