Hey all, my A/C on my 91' 740 has stopped now after about a year of running. I have converted it to R-134a last year and it ran fine up till now. I have so far tried taking the two wires from the pressure switch and combined them to try to make the clutch work after looking at the pressure on the A/C system. There is more than enough pressure. All that I can figure is that the clutch is broken. Any idea on how to remove the clutch?

 

Ok, found that I can get a used compressor from a place in Atlanta for about $125. That makes it less of a hassle replacing the clutch. But what has to be removed, besides the in and out going lines and the belt just to get the compressor out?

 

You will probably want to remove the alternator, for easier access and less cussing of Volvo engineers..

BTW, re your 134A conversion: 134A molecules are much smaller than R12; so much so that 134A hoses have an inner lining to prevent this. Unless you, or whoever did the converting, changed the hoses you will gradually lose refrigerant over a period of time, depending on how much you use the AC. Since the refrigerant also carries the lube oil for the compressor, you may have lost enough refrigerant that the compressor seized and burned up the clutch. Keep this in mind, when you replace the compressor. The low pressure switch that cuts voltage to the compressor is a safeguard, but not a guarantee, and running the compressor on a low charge (although still above the low pressure switch cutout threshold) is definitely undesirable. Also be aware that the 134A charge in a conversion is less than what is called for with r12; I believe it is something on the order of 80% of the R-12 charge.

 

Thanks for the reply. I have replaced the lines from the compressor because they leaked from the dry rot. But as I have said earlier, there is more than enough pressure for the pressure switch to work. My father and I cleaned out the whole system with some special cleaning fluid that was put through the compressor and the condenser and cleared them out with a blast of air. We put oil and refrigerant in the system after a friend of ours put the A/C system on a vacuum. And noted on the alternator removal. Also found that there are two wires to the compressor, one is grounded to the car and the other is plugged in.

 

Make sure you replace the Orfice Valve.

 

I replaced that valve last year when I changed to R-134a from R-12.
Also, my father and I both replaced the compressor with a used one. Thanks for the tip on removing the alternator.
Now, I need to figure out what to do with the old compressor. Any ideas?