A/C Sometimes works... sometimes not

nightwing · 08-03-2014, 12:57 AM

Hi all-

just thought i ask the gurus here since i couldn't get a comfortable answer from thread searches or google- my a/c for my 2011 e92 sometimes works and sometimes it doesn't.

it would just blow air and it wouldn't be cold... sometimes it would fix itself when i shut off the car and start it up again. maybe it has to do with the low pressure senor/switch? any insight would be helpful! Thanks!

Bubbles · 08-03-2014, 07:50 PM

Quote:

Originally Posted by nightwing

Hi all-

just thought i ask the gurus here since i couldn't get a comfortable answer from thread searches or google- my a/c for my 2011 e92 sometimes works and sometimes it doesn't.

it would just blow air and it wouldn't be cold... sometimes it would fix itself when i shut off the car and start it up again. maybe it has to do with the low pressure senor/switch? any insight would be helpful! Thanks!

Evaporator leaks are common.

kenwelch · 08-03-2014, 10:04 PM

Have the pressures checked. Maybe you are right on the limit for low pressure, so sometimes you have enough pressure on the sensor. If the temperature condition is cold enough you might be under the pressure needed on the sensor.

If the evaporator develops a leak then pressure will keep dropping and the system will not allow the compressor to run. If the compressor cannot operate then you will NEVER have cold air.

With the engine off locate the front of the a/c compressor using a flashlight. It is mounted low on the passenger (right side) front of the engine. The compressor uses a magnetic clutch that allows the compressor drive to be activated electrically. The pressure switch prevents the electrical connection and compressor operation when there is low pressure.

Now with the engine running watch the front of the compressor clutch and have a helper turn the a/c on then off. You should hear the click of the magnetic clutch and see the compressor drive rotate with the belt.

The video will help with the clutch operation. Your problem also could be electrical, but forget the hammer method shown in the video.

nightwing · 08-06-2014, 12:23 AM

Thank you so much with your thoughts and insights. I definitely learned something new! So it looks like everything works as long as I shut off the a/c then eventually the fan before I shut off the car. Same with powering it on- turn on the fan then eventually hitting the a/c button. I guess I have to baby it?

Although- for the time it wasn't working, it was pretty humid out. Not sure if that's a factor.

08-03-2014, 12:57 AM	#1
nightwing New Member 2 Rep 16 Posts Drives: M3 E92 Join Date: Mar 2013 Location: California iTrader: (0)	A/C Sometimes works... sometimes not Hi all- just thought i ask the gurus here since i couldn't get a comfortable answer from thread searches or google- my a/c for my 2011 e92 sometimes works and sometimes it doesn't. it would just blow air and it wouldn't be cold... sometimes it would fix itself when i shut off the car and start it up again. maybe it has to do with the low pressure senor/switch? any insight would be helpful! Thanks!
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08-03-2014, 10:04 PM	#3
kenwelch Lieutenant 96 Rep 545 Posts Drives: 2008 E92 M3 M-DCT & 2017 440GC Join Date: Dec 2006 Location: Mission Viejo, CA iTrader: (0)	Have the pressures checked. Maybe you are right on the limit for low pressure, so sometimes you have enough pressure on the sensor. If the temperature condition is cold enough you might be under the pressure needed on the sensor. If the evaporator develops a leak then pressure will keep dropping and the system will not allow the compressor to run. If the compressor cannot operate then you will NEVER have cold air. With the engine off locate the front of the a/c compressor using a flashlight. It is mounted low on the passenger (right side) front of the engine. The compressor uses a magnetic clutch that allows the compressor drive to be activated electrically. The pressure switch prevents the electrical connection and compressor operation when there is low pressure. Now with the engine running watch the front of the compressor clutch and have a helper turn the a/c on then off. You should hear the click of the magnetic clutch and see the compressor drive rotate with the belt. The video will help with the clutch operation. Your problem also could be electrical, but forget the hammer method shown in the video.
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08-06-2014, 12:23 AM	#4
nightwing New Member 2 Rep 16 Posts Drives: M3 E92 Join Date: Mar 2013 Location: California iTrader: (0)	Thank you so much with your thoughts and insights. I definitely learned something new! So it looks like everything works as long as I shut off the a/c then eventually the fan before I shut off the car. Same with powering it on- turn on the fan then eventually hitting the a/c button. I guess I have to baby it? Although- for the time it wasn't working, it was pretty humid out. Not sure if that's a factor.
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