I'm having a problem with the A/C on my 325i and I can't figure out why. THe compressor keeps cycling on and off, and it makes a wierd squeeking noise when it does. The low-side pressure is about 30 lbs, it's full of R12, and the sensors on the reciever-dryer seem to be working (if i unplug them, the compressor de-clutches entirely, so i believe they are working). What else could cause this? the car has a new evap core, new reciever-drier and has been filled with the correct amount of refrigerant. Thanks.
-
-
Original compressor? How much oil was put in? Could also be the compressor clutch.Old and improved:
-
Squeak.
Most common squeak is the belt. Could be loose or have a hardened v-goove area that's not seating good in the pully. If it's the compressor, it could be like EtaSport says or worse!
Comment
-
I'm pretty sure the oil level is correct, i had it professionaly filled by guys i trust. I don't beleive it's the clutch itself, as it seems to engage and disgengage on 5 or 10 second intervals. I figure if the clutch were bad, it would just fail to lock completely? But the longer i run it, the less the clutch is willing to engage. The compressor is original, and it's always worked up until now.Comment
-
Oh yeah, one more thing: The sight glass is completely empty. I think there is about 32oz in there right now, and it does blow really cold when the compressor is on. So it seems like there is plenty of coolant still there, i dont think any has leaked out as the low-side pressure has been the same over the last month. Yet the glass is empty. wwhhhaaa??? Also, are there any other sensors on the system for temp/pressure/whatever other than the 2 on the reciever-dryer?Comment
-
Update:
The A/C satys on for about 2 minutes after initially starting the car before the compressor starts to de-clutch. Sometimes the clutch disengages, but the rpm's stay high and the aux fan stay on, like the car was intending to have the clutch engaged. This happens 4-5 times a minute, and the longer the A/C runs the longer the clutch spends in the disengaged position. It is during these de-clutching times that the squeek is made. However once or twice a minute the clutch will disengage completely without squeeking and the rpm's drop and the aux fan turns off, like the car is meaning for the A/C to turn off. Could this be a sign of over-filling perhaps? too much coolant creating too much pressure and turning the compressor off? Any help is greatly appreciated, it's supposed to be very hot here the next few days.Comment
-
Update:
I tested the 2 sensors on the reciever-dryer and the wire coming from the compressor. THe voltages stayed constant as the clutch squeeked and turned off. They only changed when the system itself shut off and the idle dropped and aux fan turned off. SO they all appear to be working ok, I can't see that the compressor is getting any false signals causing it to de-clutch. SO the next question is: can an electro-magnetic clutch fail? It's not like it slips all the time, most of the time it runs just fine. But about 30% of the time it squeeks and becomes disengaged. The olnger the A/C is on, the more it slips. Is there any way to test and check the clutch? Can it be replaced without replacing the whols compressor?Comment
-
Yes, the clutch can fail. You should be able to replace it, but I'm not sure on the one bmw uses.Old and improved:
Comment
-
A test.
Disconnect the belt and turn the compressor by hand. It should be smooth. You can feel bad bearings. If the compressor is smooth, the clutch is bad. Is there oil on the clutch or the compressor - bad seals.By original did you mean 15+ years old? Just replace it and convert to R134. They don't last forever.Comment
Comment