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A/C problems.

3K views 9 replies 5 participants last post by  E39M5 
#1 ·
Yes- I did search.

Car: 2002 530
Problem: A/C blows hot air only.

The knob is turned to the blue side so thats not the problem
The litle snow flake is pressed on the climate control panel, so thats not the problem

You might think that I need to recharge the AC and check the pressure. Well the pressure is at about 70 psi, and has plenty of refrigerant.

My outside temp sensor is working fine.
My aux fan is working fine.

I checked the fuses to see if thats the problem. It says fuse 9 +20 control the AC , I replaced those but still it only blows hot air.

So what do you think is keeping the compressor from kicking in?
 
#4 ·
I'd hate to think it was a bad compressor, as that would be a pricey fix any way you look at it, but before you go that route I would take it to an a/c specialist shop and have them connect your system to their diagnostic a/c system tester. When I bought my old e36 325i, the a/c didn't work, and apparently had not worked for years, and I couldn't figure it out, and brought it over to a local shop that fixed me up. Didn't need a new compressor, but they did a good job overhauling everything and replaced some parts. Cost me less than $300, but they seemed to know what they were doing and zeroed in on the problems after hooking it up.
 
#8 ·
70psi on the low side is too high. You need to raise the idle to 1500-1700 rpm for about 3 or 4 minutes and you should see a reading of 25-50psi. It sounds like your system is overcharged. Overcharging can certainly cause warm air to be blown out of your vents. And if your low side is that high, I can only imagine what your high side must be. This is probably why your compressor is not coming on. It tries too, but the high pressure cutout switch keeps shutting it down to prevent too much pressure bursting your lines. I would bring it to an a/c shop and see what they think.
 
#10 ·
UPDATE

I had the car scanned and it showed a bad sensor. They were able to turn the compressor on through the computer.

The AC has a bad high pressure sensor. I'm told there are two sensors. One is on the Receiver/Dryer and the other is on the AUC.

I found one of them on realoem, but I cant find the other one.

SENSOR F. AUC Part Number 64116917001
 
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