540i Climate control power issue

[Kschmat]

Hey Guys,

I have a 95 540i which I recently picked up a few months ago. I’ve noticed the AC will work well for a few days (blows cold, all the functions work), but then I’ll go to start it up and there will be no power. When this happens the Ac/recirculate air/rear demister Buttons don’t illuminate and the blower motors do not work either (the backlighting will work when headlights are on). After a few hours or days, I will start the car and it will be working again. I have checked the fuses under the hood and I have removed the climate control panel from the dash, all the wires seem to be firm in place.

has anyone encountered this issue before or does anyone have any general ideas of where to start looking?

thanks !!
Kurt.

[shogun]

you mean the engine will not start? Have you checked both fusible links near the battery? https://www.bimmerforums.com/forum/s...=fusible+links

[Kschmat]

you mean the engine will not start? Have you checked both fusible links near the battery? https://www.bimmerforums.com/forum/s...=fusible+links

The engine starts fine, the issue is that the climate control panel will randomly not get power to it when I start the car in the mornings.

[moroza]

Hello and welcome!

Do you have IHKA or IHKR?

IHKA - automatic heat, cooling, and air distribution


IHKR - automatic heat, manual cooling and air distribution.


Assuming it's IHKR, check the blower relay. It powers not only the blower circuit through Fuse 19, but also the IHKR control module, which powers the buttons. One way to diagnose is to check for 12V at those fuses, with the key in RUN. See wiring diagrams page 6450.5.