TimGinCentralNJ
08-11-2004, 01:11 PM
Thanks to many of you who chimed in on my issue, my friend and I finally got some time to identify/resolve my A/C issue.
Here's the orig post:
http://www.bimmer.info/forum/showthread.php?p=27965
Since the system was upgraded to R-134a by the PO, my A/C would always cut-out on hot days, as well as on warm days when the vehicle was at rest. On cooler days (with enough humidity to make me want A/C), the system worked great. Turns out, this was because too much 134-a was put into the system. Because of the fact I continued to use it, conditions permitting (also while I was troubleshooting it), eventually the pressure switch burned out.
My new-found understanding is, your A/C system's pressure is EXTREMELY affected both by ambient air temp, as well as how much air is coming across the condenser. The difference in a functional vs. non-functional fan clutch or aux fan is tremendous, so as it's been stated before here, always check the simple stuff first. Because of the fact my A/C would work fine on cooler days, once it got hot out (or the car was stationary), the pressure was enough to trip the pressure switch and disable the A/C. By lowering the low-side pressure to 32-35 psi during operation (later I also installed a new pressure switch) my A/C is now blowing between high 30's and low 40's. I neglected to note the current static system pressure, but believe it's somewhere in the low 90's. Since my new fan clutch locks up about as well as my old one, I probably didn't need to replace it, but what's done is done.
Again, thanks to everyone here for the "assist". Damn, is it nice having A/C again....
Best Rgds,
Tim "No mo' sweaty buns here" Goodell
Here's the orig post:
http://www.bimmer.info/forum/showthread.php?p=27965
Since the system was upgraded to R-134a by the PO, my A/C would always cut-out on hot days, as well as on warm days when the vehicle was at rest. On cooler days (with enough humidity to make me want A/C), the system worked great. Turns out, this was because too much 134-a was put into the system. Because of the fact I continued to use it, conditions permitting (also while I was troubleshooting it), eventually the pressure switch burned out.
My new-found understanding is, your A/C system's pressure is EXTREMELY affected both by ambient air temp, as well as how much air is coming across the condenser. The difference in a functional vs. non-functional fan clutch or aux fan is tremendous, so as it's been stated before here, always check the simple stuff first. Because of the fact my A/C would work fine on cooler days, once it got hot out (or the car was stationary), the pressure was enough to trip the pressure switch and disable the A/C. By lowering the low-side pressure to 32-35 psi during operation (later I also installed a new pressure switch) my A/C is now blowing between high 30's and low 40's. I neglected to note the current static system pressure, but believe it's somewhere in the low 90's. Since my new fan clutch locks up about as well as my old one, I probably didn't need to replace it, but what's done is done.
Again, thanks to everyone here for the "assist". Damn, is it nice having A/C again....
Best Rgds,
Tim "No mo' sweaty buns here" Goodell