Thread: aircon no go

1stly, is the system out of or low on gas? You can check this by bypassing the low/ high pressure switch to see if the compressor switches on. The switch is located in front of the brake M/Cyl, and has just a 2 pin plug . Unplug it with the engine running and the compressor switched on, and connect the terminals of the plug with a split pin or similar. If the compressor engages, the system is low on gas. There is also 2 sensors on the thernostat housing / top hose elbow. Unplug both*, and bypass them in turn also, same method.(*Only one is for the compressor, but I can't remember which it is!)If this turns on the compressor, the sensor is an overtemp compressor cut out and will need replacing if faulty, or you can leave it disconnected and bridged if you like.
Finally, have you had the A/C belt come off at some stage? This can cause the belt to cut the wires behind the compressor clutch, and requires removal of the clutch and some soldering to repair.
Give me a call tomorrow on 6229 1102 and I'll talk you through it if you like.
Have fun!

JC

Morning JC,

I'll have a look at the plug latter tonight. Just as well it's cooled down - bit chilly this morning. Are the two sensors to which you refer on the bottom of the thermostat housing? I changed the plastic plugs this weekend for S/S plugs, had a bugger of a job to get the thermostat plug out and damaged the threads. I used the new plug to cut a new thread, which sort of worked. ended up using some epoxy resin to seal it. In the various trials a lot of fluid would have found it's way on to those two sensors. Maybe coincidental, but I doubt it.

By the way JC it's Graham here!

Thanks for you help, as always!

Originally Posted by Shifter

Yesterday for no reason my air con compressor failed to clutch in. Checked the belt - OK, Checked the fuses - all appear OK. Pressing the button on the dash the small indicator light comes on, the condensor fan starts but the compressor clutch will not come in.

Anyone any ideas where to try next??? Perhaps there is a solonoid to somewhere which brings the clutch in??

i have the same problem with mine except, mines never worked.
Had it down to the a/c bloke he found a hole so I replaced the line now it holds gas, but the guy recons that there is no power coming forward from the firewall to the pressure switch or the compressor, although the switch inside lights up and the fans come on. He claims to have put power directly into the compressor and the clutch engages but other wise there is no go. But I might have a look at the pressure switch check but the other switch check looks to be a bit out of my league. Let me know how you get on

Played with the system this morning with my multi meter. Found that the sensor fitted to the front of of the thermostat housing is the problem. I removed the plug connection and as JC suggested fitted a link wire to effectively short out the sensor. As soon as did this and started the engine, hit the on button, the compressor started. Problem solved. I'll as JC is he can supply a new sensor or maybe just run with it shorted.

Kingy, have a go at what I did to see if it helps?

Hi Graham, I have one if you need it, give me a call Monday, or just drop down.

JC

Thanks JC and Shifter, had a look at the thermo housing turns out we have the same prob except the compressor plug is the rear one on mine (the one furthest from the radiator)
When I removed the plug and looped a wire between them and restarted the donk turned on the a/c success the compressor engages, how ever its to cold now to tell if its getting cold but did check the lines at the compressor one is cool and one is hot (the a/c guy did say that it still needed more gas but it should be enough to get it working), I’ve got it booked into LR in port melb soon at least I know what the prob is so I might just get them to replace the faulty sensor and top up the gas. Phew what a relief to know what the problem is and that it’s not terminal. Thanks very much guys give yourselves a big pat on the back.

David

Kingy and Shifter,

Glad thats solved.

It is ,according to the RAVE disc, an overtemp compressor cut out sensor. It's job is to prevent the A/C from working when the engine is running too hot. The sensor next to it is a cut IN switch for the A/C fans, incase the engine is hot and needs extra cooling. I assume that one is normally open, and one is normally closed. I must check a known working example on Monday to find out...I've had no problems so far bridging the A/C compressor cut out one, but I would probably replace it anyway. The last one I had to do was from an engine that had an overheat, possibly this is what ruined the sensor in the first place.

JC

JC, I'll call down on Monday arvo if I get a minute. I looked it up in my Haynes manual and worked out what the sensors did. I don't really think I need one as I would never overheat my engine - would I???!!!! But **** happens, so I think I'll replace it as long as new sensors are cheap?

Kingy - pleased to be of some help.