You can diagnose the pressostat yourself. If you take off the connector to the pressostat and jump the pressostat wiring harness, and the compressor runs, you don't have a bad pressostat.

If it doesn't run, you have a problem with the compressor or the control unit not giving power to the system (possible). You can actually hotwire the compressor wire straight to the battery, to see if it runs like that. If it does, the problem lies elsewhere. Only do that for a second, though... you can cause current backfeed.

With respect to charging the system, you can do the recharge yourself. It's so cheap, you hardly have anything to lose. I'd recommend also buying at LEAST a low pressure side gauge. See if you can get one that registers the lbs. of refrigerant pressure, not just one that shows the acceptable color ranges. You need to know the pressures at least on the low side (preferably on the high side as well) to know what's going on in the system.

Since the conversion has been performed already, you should be home free to recharge the system. If it's leaking or has been empty for a while, replacing the suction accumulator is highly recommended for longer system life. One sample charge will help you figure out if it's leaking out or if there's another problem.


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chris herbst, five volvos.