Volvo: 1994 940 Air Con Dash Switch, volvo dealer, salvage yards

Question
Hi Ray,
When I turn on my AC with the dash switch, it does not load my engine (i.e., there is no rpm drop at idle), and my AC does not work.  My fan works fine, but the air it blows is not cooled.  My local Volvo dealer charged the AC system (for over $200), and sent me on my way with, it turns out, my AC still not working.  I took it back the next week, and this time they said the dash switch needed to be replaced (for $875 plus labor!)  Frankly, I no longer trust these guys.  They seem to know nothing about troubleshooting, only how to replace parts--in the hope, I guess, of eventually replacing the correct one.  I suspect the switch IS the problem, and that the fluid level was fine all along.  But $875 for a switch!!!?  This seems outrageous.  What do you think?  Is it the switch?  Can't these things be repaired?
Regards (and thanks in advance),
Jack

Answer
Jack,
Those dash mounted switches go out often. With the A/C turned on is power flowing to the low pressure switch? If not when it is power supplied does it work? If the system works then sounds like a dash unit is needed. You can also try salvage yards for used parts. The unit itself maybe repairable, but not usually the way it is fixed. It may have a cracked circuit card or bad solder joint, most places will not repair that sort of problem, they will replace the unit. I also have seen the use of a toggle switch to operate the A/C.