Air conditioning issue

[v6camrydriver]

Hi all. I live in quite a humid area so need the air con running on cold mornings to keep the window de-fogged, however the last few mornings the air con hasn't turned on as normal. The fan is on and when I push the 'AC' button the light comes on and stays no (no flashing) but theres no change in engine rpm or the tell-tale hissing of the evaporator working, and the windows stay fogged. The stange thing is that once the engine has warmed up a bit it works fine!!!I don't know if it's to do with the winter cold as it's worked fine before even when the car has been completely iced (which was only the other week!).I just want to know if someone else has had a similar issue or if anyones gotr any ideas before I start diagnosing.Quick stats:'94 V6 GL (NZ)374,000KmManual air con system.

[Stillrunning]

First check that the compressor clutch is engaging and the pulley turning. Also check belt tension.

[v6camrydriver]

Originally Posted by Stillrunning

First check that the compressor clutch is engaging and the pulley turning. Also check belt tension.

Thats part of the problem...once the engine is warmed up it works with no hint of problems.Maybe I need to check it in the mornings when it's cold and hope that pesky Murphy isn't about...

[davemac2]

check to make sure your radiator fan is coming on fully when the A/C is turned on before the car warms up.

dave mc

[v6camrydriver]

Originally Posted by davemac2

check to make sure your radiator fan is coming on fully when the A/C is turned on before the car warms up.

dave mc

Did a bit of diagnosing today and found the following:
- When on maximum cooling the AC compressor works, the engine idles up like normal and the cooling fan speeds up to maximum. Looked at the sight glass and it is clear when running and foams up then clears when turned off. There is also a temp difference between the compressor inlet and outlet pipes.

However the system is still working intermitantly, and the other day wasn't working when I got to work.
I'm begining to think it's an electrical problem...just not sure exactly where. If it is it will most likley be a wiring issue or a faulty sensor issue, possibly the low pressure switch.

Has any one had a similar issue? If so what was the outcome?

To reiterate:
When the system works it works great and like it always has since I got the car.
When it dosen't the following happens when the fan is on and the AC button is pushed:
The ac button lights up and stays lit. There is no sound of the ac compressor clutch engaging or the evaporator working and no engine idle up.

[Dave's]

Different car but I once had a similar problem and it turned out to be relay controlled by the A/C button was loose. The coil worked but the contact tabs would lose connection intermittently. But it happened randomly regardless of engine temp.

[v6camrydriver]

Originally Posted by Dave's

Different car but I once had a similar problem and it turned out to be relay controlled by the A/C button was loose. The coil worked but the contact tabs would lose connection intermittently. But it happened randomly regardless of engine temp.

Will check it out on the weekend.

[v6camrydriver]

**UPDATE**Took my car to the local Air Con shop the other week and the guy replaced the expansion valve, various seals, the drive belt and re-charged the system. It is working a lot better although this morning was a particualry cold morning (not icey mind you) and it didn't work till long after the car was warmed up.Am wondering if perhaps the temperature switch is faulty as the air con used to turn on fine no matter how cold it got (including times that the car was completly covered in ice).