A/C Not Working But Has Gas

Question

I have a commodore which does not have a working A/C in it which has become a major issue now with us being in an Australian summer. I believe that there should be no issues with the gas as it was re-gassed less than 12 months ago. I have gone online to try and find out how I could trace out the problem but it has seemed difficult to follow, I have done the following...

1. Checked the Fuses (fuse chart doesn't match up with the actual physical fuses but have gone through all of the fuses and can't find any blown fuses.
2. Checked the compressor (inner clutch isn't engaging, which I checked from the front the outer wheel contacting the belt turns with no issue at all but non of the mechanism on the inside visible from the front turns at all and there is no change in engine rev's whether A/C is on or not).
3. Checked the A/C cooling fins (mini radiator on front) and was all clear, only a small number of bugs but no obstructions at all, almost every single gap between the fins where clear.

Some of the checks I was suggested to do which are causing me some issues are...

1. Bridge the pressure switch (the advice I was given was that it would be easy and that it would tell me if pressure was in fact the issue and that I would have to just pull the plug off the pressure switch and bridge the two contactors inside it but there are actually 3 not 2 wires).
2. Jump the compressor from the battery to the terminal on the compressor (I was told one wire would be there and that the compressor is grounded through the body and bolts but the compressor has two wires connected to it from the top, additionally I am concerned about if this could burn something out by bypassing any restrictions in place to power going to the compressor directly).

The heat function works with no issue and the vehicle blows hot air like its going out of fashion but it does so even when the temp dial is set to full cool. The main fan obviously works as the air comes through super strong.

I have a 8 month old son going through his first hot season of his life and he struggles every time we go for a drive without an A/C, unfortunately this close to Christmas all funds have been used up for the season so can't afford to take it into a mechanic and get them to fix it so trying to find out how to get this working myself or at least how to finish testing and identify the actual fault.

Answer 1

Provided the refrigerant has been recharged to the correct level, there is a strong possibility the issue relates to lack of signal from the pressure switch, the pressure switch is needed to engage the compressor clutch. I know for a fact that on my VW Touareg the compressor will not engage if there is no signal from the pressure switch.

Note that your switch could be fine but there could be a loose connection or open in the wiring that is the root cause of your cooling woes.

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Regarding the concern regarding three wires instead of two, I can only guess that one of those wires is the ground wire.

The easy way to verify which one is ground would be to use a multimeter in resistance mode with one of the terminals connected to a known-good ground location on the vehicle. The ground wire will register a very low resistance; the other two should register some resistance or an open.