our problem began with snowflake turning itself off intermittently for a day or two and now won't turn on at all. within a couple days the auxiliary fans went out (coincidence?) but we replaced the whole shroud and that is fine now, fans come on.

still no ac.

we also had a pressure test done and all that is okay - they said it must be electrical. one mechanic replaced the high pressure switch and mentioned the control head but i want to test it (and other, cheaper things) to make sure before spending that much.

the climate control display gave us these malfunction codes:
22.1 - F118 AC high pressure switch static open
7.3 - Ambient temp sensor at fresh air blower sporadic open
8.3 - Temp flap regulator motor (potentiometer?) sporadic open

this is after the high pressure switch was changed. maybe the mech didn't clear that code? also, when we jumped the ac clutch relay we got sweet, cold air! but not sure exactly what that means . . .

thanks for the help!

 

pm me your email.. I have the wiring diagram that can help narrow it down.

btw.. those three all have the same ground point: G202 - Behind left side of I/P

 

hey jim - good to see ya again. thanks for your help with the fans- they are running great.

heres some additional info that i've found by surfing:

i saw on one site that if the high pressure switch cycled on and off too many times the diagnostic trouble codes would need to be erased before the compressor would engage. i have a new switch on there - could it be that simple?

also, this sounds just like what happened to me -
cycling every 3 or 4 secs, fans broken, etc,

"The engine cooling fan- there are 2 of them, and they run at half speed all the time the a/c is on. The more load on the system, the higher the high side pressure goes. If it reaches 17.5 bar, then both fans go to full speed. If the pressure carries on going up (which is very unlikely), then the HP switch cuts the whole lot. When this happens, the pressures subside, and the whole lot turns itself back on when it drops to 28 bar. If there's something wrong with the system, then the pressures shoot up to 35, it cuts off, and so on. You will normally notice this happening as it will cycle every 3 or 4 seconds, jolting you about as it bangs on and off, loading then unloading the engine.
As I said before, pressures will only normally get up this high if the fans fail, and only show itself when it gets really hot. It may be the switch has just plain broken, in which case none of the above applies, but as the switch is actually a 3 position switch, that opens at low pressure, closes at normal pressure, then opens again at high, it seems a bit odd that it has failed on the HP part, whereas one would expect it to fail to the low pressure setting. That's why you just need to check that it's a straight switch failure, and not one preceded by a high pressure situation, otherwise you'll be back there again with poor a/c."

could the fan problems have re-damaged my new high pressure switch? or did the tech who replaced it not erase the codes and now the compressor wont come on? or something completely different?

 

The high pressure and low pressure switches are separate. Its not a 'on/off/on' switch.

Not really sure whats going on. This is one of those problems where the person doing it really needs to be there looking.

However, this really seems like a bad ground (G202), or a bad control unit.

 

i have the same problem. And i fixed it the same way, i jumped it and got cold air blowing fine.
Did you ever resolve it? My had an error reading of Clutch Air Space.

The dealer told me i needed a new compressor because the clutch was worn down.

 

I have not tried this on my Audi but on our Volvo's this was common. Basically the clutch material within the compressor has worn down. Just like a clutch in a car. The difference is that in the compressor, there is plenty of life left in the clutch material its just that the clutch plate is too far from the compressor. If you remove a shim (basically a washer), there are several that space the clutch from the compressor you can reduce the air space.

It's really an easy job once you have good access to the compressor.

 

Can anyone verify what Jeffla said?

It makes a lot of sense.

 

i thought the mech said that on my car there is only one switch that is high/low instead of 2 separate ones. should i still be getting the code that my high pressure switch is open even though i have a new one installed?

also, how do i test the control head - when i jumped the relay and got cold air the snowflake came on and everything looked fine there.

we cleaned that ground before when we were trying to fix the fan so i think that is fine. - is there something else we should do to check it?

 

Here is a Saab writeup. Maybe it was my Saabs and not the Volvos I had to do this on. I owned so many Saabs/Volvos they tend to blend together.

http://www.saab9000.com/procedures/v...rconclutch.php

 

Do you have access to a vag-com? If not track down someone locally and clear the codes.