but the AC fan is supposed to run as long as the AC button is on right? and always turns on at startup for a few seconds to let the DME know its working?

is that right or wrong.

So... Sunday evening, I removed the airbox and was looking for this pressure sensor along the lines. Found one under the airbox. 4.8iS model.
Anyway. There was one there. I unplugged it, sprayed some contact cleaner there and then I reconnected it.
Well, the AC hasn't done the random cut out since. That includes a trip across town and back yesterday as well as to and from work both days in this 100+ degree weather.
So I may indeed have a bad sensor.
Question is, is I unscrew it to change it. Will freon escape out into the atmosphere? Or is it safe to change out just like that.


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You can't replace without a freon evacuation, vacuum and fill. If the sensor is bad and freon full I personally would short out the sensor since I check my pressure regularly

What would shorting it out do.
What exactly does the sensor tell the system?



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Sensor protects the compressor by disabling the compressor when there is no freon. If you are absolutely positive there is freon you can force it to work when the sensor is broken "open" by shorting the connector.

You risk damaging the compressor should the freon leak out and you try to use it

Ahhhh. I see now. Ok.


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Since open turns on the fan that must signal high pressure to the IHKA so shorting the circuit would probably signal low pressure (low freon) and the system would not turn on. Anyway why would you want to replace the sensor if you suspect the problem was the connection? If you do need to change the sensor there is a chance that there is a schraeder valve under it but maybe try to verify that(maybe someone can chime in on that) before hand. Having the system work after cleaning the connections doesn't really match with the theory of operation of the sensor unless the IHKA is reacting by shutting down the system if it sees confusing readings. Interesting.

Ok so we swapped compressors and recharged. I got AC all that time now. And a lot colder than before. So if your car takes a while to get cold but then stays like that the rest of the day only to stop working when it’s been sitting for a couple hours it’s 100% the compressor.

There are no "100%" in car repair or there wouldn't be forums such as this only one big checklist.

That said, the problems are much easier to solve when you have the proper symptom diagnoses: in the case of AC it's nearly pointless to work without measuring both high and low pressure

AC Takes forever to blow cold.
 

So I think I found that high pressure sensor. I unplugged it and cleaned it. This was Sunday, or Monday. Can't recall.
Anyway, I have a 20 minute commute to work. I drove the X5 to work everyday but Friday and the AC never cut out like it's been doing. I left it on all the time, even with windows down.
Anyway, today. I had to step on it to beat a red light on he way home after running around all day doing errands.
Transmission kicked down two gears. Then literally as I cleared the light. The AC stopped cooling. What was odd. Is it was over 100* F. But it wasn't instantly hot as balls like it normally is when it cut out. It was like the temperature was set to 75 with the AC on.

Any thoughts?
I'm thinking that it's a leak somewhere for sure.


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