AC not working on 1993 Volvo 940

The AC fluid was empty, we had the fluid filled but the compressor was not turning on. We hard wired the the compressor to the battery to check if it would engage the AC system and it worked the compressor turned on and the AC was working. They indicated that its proberly a electrical issue, I checked all the fuses and they were all working fine. The AC button on the panel is not triggering the compressor to turn on or the ac relay may need to be replaced. Any suggestions or recommendations would be helpful.

Asked by for the 1993 Volvo 940
Check the A/C Control Panel, I have seen these fail on this model. You'll need to verify that the Control Panel is sending power to the compressor when it should, so check all the inputs to the panel and the output to the compressor.
Where is the ac control panel located
It's the panel in the dash with the A/C controls and switch on it.
2 answers 2 comments
Enthusiasm without full knowledge could potentially RUIN a possibly otherwise fine condition and VERY EXPENSIVE AC Compressor. Expensive Vacuum equipment is REQUIRED for adequate performance; as are leak detection equipment. Ask a knowledgeable person to check for a good connection and/or corrosion at the thermo switch that tells the compressor to go on and off. The switch is in the sometimes somewhat shiny aluminum AC line under the hood; a perpendicular littlle fitting with a usually black connector and, obviously electrical wires. Sometimes a quality SERVICE Manual is the best bargain you can find; EVEN if you pay a real pro to isolate, fix or both; i twill make you a wiser consumer of a professional's services. As an example; it may just be an overheated, stuck , corroded or bad AC relay; but even relatively simple problem tracing can take some insight