Update on A/C system problems

[632 Regal]

something stupid that I must mention here, if the blower switch is all the way to zero or counter clockwise the AC wont turn on. Sorry if this is a real lame comment but when I bought my car I got additional off cause the air didnt work...thanks to my son we fixed that problem on the way home.

Check yout switches for power at the drier and whatever, one side should definetly have 12 volts when the system is supposidly on, of the other doesnt thats the switch you need to replace.

[NoSpeedLimits]

Nothing is too stupid...we all have had those momentary oversights that remind us that we are only humans. On this particular item, I fortunately did not, and I can confidently say that the blower functions as it should in all positions of the dial.

I could be mistaken, but IMO I feel that the green light would come on regardless if the compressor is functional, I speculate that the light only indicates power at the switch.

Winfred, since in my case the green light comes on, is it safe to assume that the main control box is okay? Since I never use them, is it easy verify that the rear window defroster and recycle operate properly?

Mr. Project, I am a little confused as to what you mean by "vehicle side of the harness." So, to bear on the side of caution, I will attempt to run out to my car and take a digital of what I believe is the lp switch and hopefully you or someone else can point out which wires to jump. In-the-mean-time, feel free to clarify it with your words and hopefully you'll save me the trouble of stepping out to take a photo -- I would be greatful since everybody in the office has a view of the parking lot and I will therefore be hammered by curious/nosey co-workers.

BTW - anyone know where the hp switch located?

[sbcncsu]

I was reading the TIS last night and noticed that the later model BMWs use combination switch that is a Low, Medium, High pressure switch all in one. Again, I don't have a bentley any longer but the wiring should be in that book. It will tell you which wires in the connector are the low, medium and high.

The combination switch is mounted on top of the accumulator (receiver drier) and has one connector with 3 or 4 wires.

[Mr Project]

The combination switch is mounted on top of the accumulator (receiver drier) and has one connector with 3 or 4 wires.

NSL, in my case I do have the single 'combo' switch on the Receiver/Dryer, but rather than 1 large connector coming from it, I have 2 small ones. Each connector on mine is 2 wires. One connector is grey, one connector is black.

By "Vehicle Side" I simply mean that when you disconnect the connectors so that you can put a jumper in, it won't do any good to jumper the side (wires) that goes to the switch. In order to 'fool' the DME (or whatever runs this) into activating the compressor clutch, you have to jumper the connector that goes back into the vehicle. Obvious, but I figured as you said "nothing is too stupid".

On my car, jumpering the grey connector activated the compressor clutch. (A/C button was "ON" in the car, probably required) Jumpering the black connector just activated the aux. fan. (probably the high-pressure switch)

I'm not sure on mine how it would determine the 'mid' level pressure by using those 2 connections. Maybe a certain combination of the 2 signals?

[NoSpeedLimits]

I pulled this image from the electronic parts catalog...based on your description, I believe the lower drier shown in the picture matches what is in our vehicle. Thanks IOU for taking the time to explain it...you saved me a bunch of unsolicited socializing.

[Mr Project]

Exactly. That #2 style is what I have in my '91, and presumably what you would have in your '94.

[NoSpeedLimits]

Okay...the verdict is in, I jumped both of the connection and the first one fired up my auxiliary fan. The second lead...drum roll please...fired up the compressor and gave me cold air. Yippy! So, I believe it is safe to assume that my lp switch needs replacement???

If my assumption is true...is it safe for me to unscrew the lp switch and replace it myself??? I am concerned about the system being under pressure and possibly causing me harm. Also, will the removal of the lp switch cause refrigerant to leak out??? Any recommendation would be appreciated. I'll check my Bentley after work today to see if they have any information pertaining to this procedure.

[Mr Project]

I wondered about this myself... on my Receiver/Dryer, the port for the combo switch has a schraeder valve, so it can be changed without releasing a significant amount of refigerant.

[NoSpeedLimits]

Thanks to BMA...I will have the replacement pressure switch tomorrow. And, if all goes well with DIY job then I should be enjoying A/C this weekend

FYI. The pressure switch p/n = 64 53 1 390 070 (BMA p/n = BM044273) and costs less then forty bucks.

Thanks for all of your help!

[TimGinCentralNJ]

something stupid that I must mention here, if the blower switch is all the way to zero or counter clockwise the AC wont turn on. Sorry if this is a real lame comment but when I bought my car I got additional off cause the air didnt work...thanks to my son we fixed that problem on the way home.

Check yout switches for power at the drier and whatever, one side should definetly have 12 volts when the system is supposidly on, of the other doesnt thats the switch you need to replace.