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Hi Brickboarders
What a fantastic site! Whilst i have a reasonably high level of mechanical knowledge,good workshop facilities etc I am learning heaps about Volvos. Thanks.
I recently rebuilt the AC on my daughter's 240 wagon "83.
It had a faulty/stuffed York ( upright)compressor caused by no gas.
I had a spare so I...
Checked the clutch ..it has a loud click/clunk when it engages..ie 12 volts is applied to the wire coming from behind the pulley.
Checked the compression/suction..place fingers/bungs over the inlet/outlet and turn compressor crankshaft..feel for shaft slack etc at the same time.
Removed pulley . Undo centre holding bolt..then use larger (3/4?) bolt as an extractor..don't lose woodruff key on shaft. Once it starts, it slips off the tapered shaft easily.
Replaced the front shaft seal...first remove the electromagnet (round black donut in silver housing fixed to front casing with 4 bolts) then remove 6 ? small bolts holding seal.
With the pulley off check the bearing..if it feels rough or lumpy when it spins Replace it!..(cheap, from a local bearing supplies)...use circlip pliers and press or gently punch out the pulley bearing. refit with spacer washers ,circlips etc.
Drained oil and replaced with new compressor oil ( 265Mil?...we use metrics in Australia)
To replace compressor you will need to remove engine pulleys and belts and remove power steering pump ( don't disconnect, simply move out of the way) then the big bracket holding the A/C compressor.
It is indusry practice to replace the receiver/dryer (long black cylinder) which takes moisture out of the system..whilst the system is "open".
New receiver/dryers have a bipolar pressure switch (referred to in other responses) this is wired between the power source and the compressor clutch and won't allow clutch to engage and drive the compressor if there is no gas/pressure in the system ..or the pressure is too high.
I had lost the gas through a hose fitting leak..there was no pressure switch fitted to the original system and it siezed the compressor! I fitted one this time and wired it as above.
My local AC shop tested the system for leaks (with Nitrogen ..which is Dry) and we replaced the faulty/leaking hose and fitted new O rings.
I intended to retro fit with R134a by he suggested remaining with R12 as R134a runs higher pressures etc and is more likely to cause problems with old hoses etc ...as described in other reponses.
A non-leaking system with R12 works fine as it has for many years!
The system now works really well and I have a happy daughter.
If you are not up to regassing ...A good AC shop will test the system for leaks and scavenge any gas in the system before opening it..you can do some repairs and fitting labour and return it to the shop for regassing.
good luck...(sorry for the long response)
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