Air con 'not working' Best next steps?

[CharlesStevenson]

From when I purchased my T4 last year the a/c's not worked (heater/cooling is ok) but I'd not investigated it until now and I'm trying to work out the best order to check things out.

I appreciate that the system's 20 years old and so well before today any of the hoses could have perished or that there's already damage to a metal hose, so I'm starting from not knowing much about it's overall condition.

All I know so far is this:

1. The drive belt's still connected to the compressor pulley and the belt runs perfectly well

2. There are no nasty noises coming from the compressor

3. When I press the a/c button on the dash the a/c doesn't engage so the engine speed doesn't change (as it used to on my other a/c x40's).


Possible issues that I've found on the web:

1. Shimming the compressor - I've read on various posts on here and elsewhere https://www.matthewsvolvosite.com/ca...limate-control and https://www.matthewsvolvosite.com/fo...ic.php?t=31130 that the pulley shim width can often cause a problem (the cable-tie fix) but that seemed to be something that shows up by the compressor working some of the time?

2. General check the fuse and relay in the fuse box - will check these tommorow

3. Thermal sensor problems https://www.matthewsvolvosite.com/vo...hermal-switch/

4. Fluid loss meaning the system simply won't switch on

5. A break in the cable somewhere

6. Pressure switch failure

7. Expansion value or some other component

8... Anything else I should know about?

AIUI if there's too little gas in system then the compressor's clutch won't be able to switch in, so perhaps the simplest 'next step' might be to take it to an aircon specialist that does a "cold or your money back" guarantee.

I know I won't be the 1st to try to fix this system on a Volvo, so what might be some good things to check, hopefully easily ... and cheaply?

Thanks