R32 Gtst Aircon Problems (no Cold Air)

[Archie]

hey guys, ive had air con trouble since i bought my gtst. No cold air

Ive since fixed leaks and replaced faulty sensors. Now diagnostics check is good, BUT, my compressor does not kick in unless i overide the computer by touching a wire from the negative terminal of the battery to the pressure switch at the front of the car where the gas cylinder is. Then the compressor kicks in and i get cold air.

mechanics have told me it could be the thermostat, and that i should try overiding that to see if its faulty. what i dont know is exactly where the thermostat is to put a wire in to overide it?

can someone post a photo or describe where this unit is, and where the connection is to overide?

Edited January 22, 2007 by Archie

[heller44]

The switch on the top of the dryer ( the gas cylinder thing ) is a pressure switch, it stops the compressor kicking in if you don't have enough pressure in the system. 'If' you have the correct amount of gas in the system, and bridging out the pressure switch gets it all working, wouldn't it appear that is a problem with the pressure switch?

Edited January 22, 2007 by heller44

[Archie]

no ive had the pressure switch changed aswell, and the gas has been regased fully too

Edited January 22, 2007 by Archie

[heller44]

check wether pin 9 on the eccs is going low 0v when trying to cool on air con. if not, then check pin 46 on eccs if that is going low 0v. pin 9 is out to pressure switch to pull aircon relay in, pin 46 is in from auto amplifier (climate control). If you don't get it there check pin 15 on climate control thats the origination point.

If your diagnostics on all sensors are good, this is about your next step.

[heller44]

rb26 diagram, but pinouts are the same for rb20

aircon_diagram.pdf

[Archie]

So if i get a reading of 0volts then that means not working?

What should the voltage read?

[heller44]

0v good. floating or 12v bad. Thats straight out of the manual. 0v to earth.

Edited January 22, 2007 by heller44

[Archie]

yeah, i had the car at the mechanic today, and he told me that there was a problem of something not earthing somewhere. i think thats why the compressor kicks in when he bridged to the pressure switch from the negative terminal of the battery.

[heller44]

With reference to the diagram, all you are testing doing that is that the aircon relay works and the compressor clutch works, not all the rest of the crap which controls it.. the ecu is what turns on the air con relay, it is just told to do it by the climate control module.

[Archie]

yep.

Thanks alot for your help man. I'll get to the bottom of this problem somehow..

[Cubes]

You say you've had sensors replaced.

I have recently had the exact same issue and it turned out my Intake air temp sensor is constantly reading -30degree's (occasionally comes up to 8degree's or so).

This stops the a/c compressor cutting in.

Have you entered the climate control diag mode and had a look at the intake temp sensor reading?

[Archie]

i have, but it was a while ago when i fixed the sensors. i might just check the diagnostics again to see what it reads now. i'll get back to you on that.

[Cubes]

Mine doesn't always show up the Intake temp sensor in the sensor check.

The only way to be sure is for myself to flick to the sensor display and check them.. Often than not when its -20 it doesn't show as faulty but it sure isn't -20degree's so its faulty and causes the a/c not to operate.

Did you replace the Intake temp sensor? I can't appear to find the sucker.

[Archie]

yeah im pretty sure i did replace that sensor. i had to remove the entire dash (which took a long time, but i was being careful not to damage anything, cos you so easily can) and then where the aircon box is behind the glove box, the sensor is one of the 3 connectors that sit on top of the aircon box.

Its the left, white connector. The middle one is black (thats the refrigerant temp sonsor connector), and the right one is white (that connects back to the climate control unit).

The actual intake air sensor is inside the aircon box (if you follow the wires you'll see). i had to pull the stuffed senor out (forcefully) by yanking the wire and dislodging the sensor. then i inserted my new second hand sensor (which i pulled from an old aircon box to get the spare intake sensor). i pretty much just had to let the sensor hang inside, cos otherwise i would of had to degas the whole system and then remove the aircon box and open it up. But i had just had it regased so i wasnt gonna do that.

[Archie]

Now ive just found out that my water temp sensor is showing up on the diagnostics check (No. 23 flashes)

Would this sensor be enough to stop the compressor from kicking in? And also, is this sensor under the car?

[Cubes]

It would if its reading too high.

I believe thats the usual water temp sensor the ecu see's

Its at the front of the motor where the top rad hose connects.

[Archie]

thanks cubes.

Hey, where abouts in SA are you? Ive been going to Synergy Motorsport at Medindie Gardens on main north road to try and get this aircon bullshit sorted. Im not sure if they still are PVP imports anymore aswell as Synergy?

[Cubes]

I'm down southish.

[Archie]

yeah, im west of the city.

You had any other problems with your car? Mines been pretty good except for this aircon.

[Cubes]

Cars been good.

Owned it for 5yrs, clocked up ~160,000km's of my own and now its starting to show its age.

The clock states its done 230,000km's.

Just bought myself a press and bushes for the front and rear I will be doing them once I get this aircon sensor and track down heater core for a reasonable price.

The highpressure aircon hose recently went after a conversion to 134a (134a runs double the pressure of the old R12 gas).

The top radiator tank let go in the early days, Natrad in the city replaced that for $90.

Clutch master and slave cylinder went, they were $75 and $30 each bran new. All Clutch and Brake at St. mary's does them so look in the SA sections workshop sticky.

Nothing else really.. Its been a great reliable car.

Only replaced motor as I got tired of the rb20 and had been building up the 3ltr for a couple of years prior so ripped it out sold it and dropped the 3ltr in.