This weekend I tackled an irritating issue with my BMW 530i. I had a problem with the air conditioning, and the recent heat wave pushed this problem into the urgent quadrant. Summer time in DC, plus my wife complaining about it meant I could no longer use the time-tested technique of ignoring the problem.
The A/C would cut out when the car was stopped in traffic. The air flow didn’t change, that stayed constant. But there was no frosty air at all, the A/C factor disappeared until the car started moving again. Pretty uncomfortable in commute traffic, to say the least. So I jumped into the forums for some research.
Turns out there is a switch that controls the auxiliary fan. The fan is supposed to come on when the car is stopped, to help cool the A/C condenser. If the condenser gets too hot, it shuts itself off. Based on my car’s symptoms, that sounded like what was happening. The entire fan could have been defective, but there was a chance just the switch was out.
So I ordered the switch for less than $20 online and installed the switch, which was very accessible in the engine bay. And for once, I got the BMW best-case scenario! It wasn’t the entire fan assembly, it was just the switch. I’ve now got cool air again at a dead stop, although I’ll probably also have the A/C system recharged before the end of the summer to get it back to 100% power.
Note to fellow DIYers — If you need to make this replacement, make sure the car is cool or you’ll lose some coolant when you remove the switch.
While I was at it I also addressed a musty A/C smell that was starting to occur, a common problem with BMWs due to moisture in the system. Thankfully, I don’t have as bad a problem as described here, or (hopefully) need as involved a remedy. I sprayed a can of Liqui Moly Klima Fresh in the car, and it seems to have done the trick so far.
All in all, another small victory in the post-warranty BMW ownership experience!