Air Conditioning - more questions??

I could use some help... over the holiday, I realized that my AC was not working on my 97 Jetta. Upon closer inspection, the clutch is not engaging (and its been in the 60's where I've been)...

I've checked several things so far:
1.) hooked up VAG-COM, no error codes
2.) Checked fuses/relays
3.) Checked voltage to clutch (none)
4.) With VAG-COM, it appeared that the temperature sensor(s) are reading correctly, but not clear which one is reported in the software?

I've ordered my Bentley manual today (haven't needed it so far with all of your great help!) but have a question since I won't get that for another week or so...

Where is the low pressure switch on these cars?

I'm used to the american style system where it sits up by the dryer, and I must be blind, as I sure can't see it on this car.

I need to 100% verify the operation of the fans (didn't think about their inter-dependence last night), but also wanted to bypass the low pressure switch.

Thanks all!

Mark

Re: Air Conditioning - Pressure Switch??

I found on my 97 passat, that it was a vacuum line that battery acid had ate thru. after replaceing the line the ac switch worked again.

Re: Air Conditioning - Pressure Switch??

On the newer cars it's up near the firewall where the pipes go through.

Found the pressure switch, didn't realize that it hung so low on the drier... incidentally, it is under the airbox behind the front passenger headlight assembly.

I do have a couple more questions, help!

My electric fans do engage when the ac is turned on, however the compressor clutch does not.

I shorted terminals 1 and 2 on the connector to the pressure switch in effort to cause the clutch to engage, with no luck. Shorting terminals 3 and 4 did cause the fans to kick onto high speed.

I measured the voltage to the compressor clutch with the pressure switch open to be 0 volts, as expected. However, when shorting the two terminals (#1 and #2) I only read 40 mV at the clutch (was hoping to see 12 volts??)

I'm waiting the arrival of my Bentley manual still... Is there a dedicated relay just for the compressor clutch? This failed somewhat suddenly, without the normal clutch cycling associated with slow freon loss.

Any help/ideas is greatly appreciated!

Thanks!

Mark