A/C problem

[ninja]

I have a problem with my A/C on my VS ute. The compressor doesn't switch on when you turn the A/C on. I have checked the fuses, which look okay. I have replaced the switch. I have replaced the relay for the airconditioner. I have had it re-gassed. When you switch the air on and the fan, the light comes on on the switch, so it is getting power there. Any ideas before I bite the bullet and get reamed by an auto electrician?

 

[vt1538]

How did they regas it if the compressor isn't cutting in??
Bridge out the two wires on the high/low pressure switch.This is the two wires that go onto the receiver dryer. If this works you have either a pressure problem or a faulty switch.

 

[kopper69]

I have been told this but have never actually checked it. Under your bonnet if you tap the air con compressor, not the part thats spinning. As in the belt should be spinning around the air con compressor but the centre probably wont be spinning. If you tap the middle it might start spinning which means the little bearings i think are gone, or something to do with the outside spinning the inside (if you know what i mean, you will when you see it). Is the fan motor operative? Is the air con pumping just not cold? Check the relays inside and under the bonnet. Swap with other relays to check.

 

[ninja]

How did they regas it if the compressor isn't cutting in??
Bridge out the two wires on the high/low pressure switch.This is the two wires that go onto the receiver dryer. If this works you have either a pressure problem or a faulty switch.

The guy that gassed it jumped a wire from the battery to the compressor. He could only let it run in small bursts, but re-gassed it that way.
When you say a pressure problem, what do you mean? The switch is brand new, so it shouldn't be that.

 

[vt1538]

The high low pressure switch will cut out the compressor when there is high or low pressure in the system.Bridging out the two wires will take these possibilities away.
Was the system low on gas when you recharged it???

 

[ninja]

It was low on gas when he re-charged it, but it now has the correct amount of gas in it, so it shouldn't be a pressure problem.

 

[vt1538]

Power goes through the air con switch, to the evaporator switch then onto the high low pressure switch.All of these need to be closed for the compressor to operate. The evaporator switch should be under the dash on the passenger side.There are also a couple of wires that go to the ecu off the relay.I am not sure if the ecu takes any control of the compressor or if they are just a signal wire to let the ecu know when the aircon is on.Try bridging the evaporator switch & see if this works.Also bridge the high low switch to ensure it is not at fault.If none of this works get back & I will see what else I can find.

 

[pj]

You of course realize you must have the fan on as well, it won't come on by just pressing the A/C button.

 

[ninja]

You of course realize you must have the fan on as well, it won't come on by just pressing the A/C button.

uh, yeah thanks pj, I have the fan on as well

 

[ninja]

Power goes through the air con switch, to the evaporator switch then onto the high low pressure switch.All of these need to be closed for the compressor to operate. The evaporator switch should be under the dash on the passenger side.There are also a couple of wires that go to the ecu off the relay.I am not sure if the ecu takes any control of the compressor or if they are just a signal wire to let the ecu know when the aircon is on.Try bridging the evaporator switch & see if this works.Also bridge the high low switch to ensure it is not at fault.If none of this works get back & I will see what else I can find.

There are a few wires under the passenger dash, are the two I'm after the ones that plug into a little square box?