If you have a mid-80s and early 90s BMW with this style HVAC panel and your AC compressor is not kicking on, try this.
There’s nothing worse than embarking on a long sunny’s day drive in your BMW E30, pressing your AC button for cool air, and getting nothing remotely cold blowing in your face. While the source of your problem might be as serious as a blown compressor, leaking refrigerant, or a dead blower motor, there is one simple trick I’ve come across that might make your AC Compressor magically come back to life.
Our friends over at the DWA Podcast ran into what they thought was a busted AC in their BMW E30 but, after finding out this simple trick, their AC compressor suddenly kicked on.
Check out the video below. mirror here.
While there are a handful of common issues that plague a faulty AC system on these E30s, according to BimmerForums user @Jeffnhiscars, these are the most common.
- Low refrigerant. The low pressure cut-out switch needs 25 psi for the compressor to engage.
- Bad clutch or power feed to it. Not likely, but I’d run a hot jumper to the compressor briefly to confirm.
- The middle slider on the HVAC panel has a micro switch that needs to be engaged for the compressor to get power. The slider needs to be 2/3-3/4 to the right.
Number 3 is the fix illustrated in the video above. @Garretvs further explains that,
“The bottom 2 sliders for air direction have to be placed off of the closed position, as they actuate a “compressor enable” switch, which could also be bad.“
So, the next time you’re in your BMW E30 and your AC kicks the bucket for some odd reason, try experimenting with your air vent position sliders and maybe your AC Compressor might kick on. If not, tough luck mate, you’ve got some diagnosing to do at a later time.