The air conditioning on my 97 Volvo 850 cuts out periodically, but as soon as I stop the car, turn off the engine, and restart it, the AC turns on and works for 75 miles or so, then cuts out again. I have had it fully charged and there are no leaks. Why is this happening and what can I do to get it to work properly?
If your compressor has the thermo switch (at the end away from the drive belt) short it out by removing the compressor electrical connectors and reconnecting with the switch out of circuit.
If you don't have the thermo switch Check the air gap on the compressor clutch, it should be about 0.3 - 0.5mm.
If it's over about 0.6mm it usually won't pull in once the compressor is hot.
Adjustment is by removing the clutch plate and removing shims, this is not possible with the compressor in situ as there is not enough end clearance to remove the plate.
You will have to dismount the compressor, to gain enough room, I managed to do mine with it still connected to the refrigerent lines but take care not to strain the joints.
You will also need to make a puller to take off the clutch plate. The 3 tapped holes in the clutch plate are 5mm and the bolt holding the plate on is 6mm. I fitted a longer bolt 6mm bolt and fitted 3 studs into the 5mm holes. I then made a steel plate drilled to fit over the 3 studs so it would pull on the end of the 6 mm bolt and pull the cluch plate off.
Once the plate is off be carefull not to loose the 1/2 inch shim washers. Remove sufficient washers to reduce the air gap to about 0.4mm then refit, the original 6 mm fixing bolt should pull the plate on again OK. Stop the cluch plate turning while you tighten or loosen the bolt by using a screwdriver wedged between 2 if the 5 mm puller studs you fit.
Do a google search for "volvo superheat" and take it from there. ~~~ "I've traded love for pennies, sold my soul for less, Lost my ideals in that long tunnel of time; I've turned inside out and around about and back and then, Found myself right back where I started again." - 'Age' - The Great Jim Croce
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