Hi,
Do any of you know how to troubleshoot the AC system in a 1990 bmw 525i e34 step by step?
Any help is appreciated!
If its not turning on the first thing i would check is if theres enough pressure in the lines, i think theres a pressure switch to prevent from burning out the pump
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What's the issue?
demet
There is enough pressure in the lines.
- - - Updated - - -
The clutch does not engage, and the fan only runs in the highest speed. I replaced the infamous "sword" resistor, but nothing changed. The resistor is in good working condition.
How much pressure did you measure?
The blower fan switch probably has bad contacts. Recommend disassembling and cleaning it. UPDATE: the blower fan and AC are separate problems.
Last edited by moroza; 05-09-2020 at 04:31 PM.
Will do!
Is the clutch being commanded on? That is a typical symptom of too low pressure.
If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue
Here is an update. The compressor is always on. It cannot be turned off at the ac control unit. The only way the compressor can be turned off, is by removing the compressor’s relay. Furthermore, the fan speed only works on the highest speed. First, second, and third speed are not functional, only fourth.
things done: I replaced the compressor relay, removed the ac control unit and cleaned it. I also replaced the fan motor resistor. My car has a sword type resistor.
It seems to me, there is a short somewhere. I don’t know where to begin looking for the short. Any help is appreciated.
Last edited by tyromechanic; 05-31-2020 at 12:49 AM. Reason: Used wrong word.
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