Trying to revive the A/C on a 72 0.cs automatic. When I turn it on, I hear a click from the compressor, the auxiliary fan turns on but the A/C blower does not. The blower goes on when I shut the A/C off. When I turn the A/C on, the blower stops. I checked the fuses, the relay below the coil, the fuse for the Aux. Fan. I also tried a spare A/C blower switch, still nothing. The blower refuses to work when I turn on the A/C blower switch. Is there a hidden fuse or relay I may have missed? There is no refrigerant but this should not affect whether the blower fan turns on or not. I verified that current is going to the A/C blower switch. Any suggestions would be appreciated.
A/C Issue
- Thread starter Tundra
- Start date
Bwana
Well-Known Member
Huh? So the blower does operate? But only when you turn the A/C off? So the blower runs all the time the A/C is off? I must be missing something here......
There are 2 blowers in the heater/AC assy. One is the heater/defroster fan (on top ,ahead of the windshield, in the cowl area) and the other is for the AC only (the squirrel cage fan in the lower console) . There is a relay that turns off the heater fan when the AC fan is energized.....The heater fan will blow air through the same vents as the AC fan if the "vent" control is turned on. Could this be the fan you are getting?
DaveG
DaveG
DaveG is correct. Sorry I didn't make it clear. It is the Squirrel cage fans that are not operating. I'm trying to avoid taking the center console apart to find out why. This is why I asked if I missed a relay or fuse other than what I described in my earlier post and the fuse box.
A/C Issue solved
Thanks to DaveG' comments and Bwana's writeup on A/C install, I solved my A/C issue. Here is what I did.
First I bypassed the A/C switch and connected the A/C blower, squirrel cage, directly to power and ground to see if it worked. Nothing happened. I then turned the "squirrel" blower by hand since it had not turned in a few years. The A/C blower then worked. But, the ceramic part of the A/C blower switch was getting extremely hot. Its obviously shot. Don't know if it can be fixed. Someone on this board probably has suggestions on how to fix that switch if it can be fixed at all. I then installed the spare A/C blower switch I had and the A/C blower works as it should. The next step is to refill the system with R12. Since the A/C has not been used for several years I'm not sure if there is anything I should do before recharging the system.
Thanks to DaveG' comments and Bwana's writeup on A/C install, I solved my A/C issue. Here is what I did.
First I bypassed the A/C switch and connected the A/C blower, squirrel cage, directly to power and ground to see if it worked. Nothing happened. I then turned the "squirrel" blower by hand since it had not turned in a few years. The A/C blower then worked. But, the ceramic part of the A/C blower switch was getting extremely hot. Its obviously shot. Don't know if it can be fixed. Someone on this board probably has suggestions on how to fix that switch if it can be fixed at all. I then installed the spare A/C blower switch I had and the A/C blower works as it should. The next step is to refill the system with R12. Since the A/C has not been used for several years I'm not sure if there is anything I should do before recharging the system.
The a/c ceramic/coil rheostat can be cleaned and oiled to see if it can be resuscitated - mine did. Here's a thread:
http://www.e9coupe.com/forum/showthread.php?t=6903
Before wasting precious r-12 (and for better efficiency), hook up an a/c vacuum pump and evacuate for at least 30 minutes or so and then turn off the pump and check the gauge to see if it holds steady vacuum for an hour or so. This will tell you if you have any leaks. If not, then refill. If it drops a little, then you have to troubleshoot.
http://www.e9coupe.com/forum/showthread.php?t=6903
Before wasting precious r-12 (and for better efficiency), hook up an a/c vacuum pump and evacuate for at least 30 minutes or so and then turn off the pump and check the gauge to see if it holds steady vacuum for an hour or so. This will tell you if you have any leaks. If not, then refill. If it drops a little, then you have to troubleshoot.
a/C Ceramic
Thanks for the link Steve. Very usefull information. Thanks also for the tip to evcuate the system prior to recharging it. Now that the A/C fan and compressor work I noticed that when turned on the compressor creates a lot vibrations in the car. Wonder if this is common with original BMW A/C install.
Thanks for the link Steve. Very usefull information. Thanks also for the tip to evcuate the system prior to recharging it. Now that the A/C fan and compressor work I noticed that when turned on the compressor creates a lot vibrations in the car. Wonder if this is common with original BMW A/C install.
Last edited:
If it is an original York compressor the vibration is likely the mounting bushings have deteriorated, although this compressor isn't smooth to begin with.