I have no power on my ac compressor, can you please help, 2000 Volvo s70

 

Have you checked fuses, is there enough refrigerant in the system, is the belt ok (granted it is a serpentine belt so if it was bad you would have other issues as well) can you see or hear the compressor try to turn on or engage when you press the AC button, are there any flashing lights on the climate control panel (AC and REC buttons)? Check these things first as well as the electrical connector and wiring to the compressor and go from there. Trace the wires from the compressor back if you can to the AC relay as well. Hope this points you in the right direction.

 

try this - on the low pressure line (the one that comes back from the firewall - look on the passenger side fender) you will find the low pressure sensor (a plug in the AC line with an electrical connector) - you can jumper the leads to see if that fools the ECC into thinking there's pressure in the system. if that kicks the compressor on, then you know you are low on Freon and have a leak to address. PS don't let the compressor run for more than a few seconds with the low pressure sensor jumpered - this is just a quick way to test.

 

Check fuses, jump the switch but the compressor has no power on that wire.

 

Could be - bad low pressure switch, bad compressor relay, bad fuse, bad compressor clutch, problem with CCM, bad signals from sensors (too hot/too cold) or simply empty of freon -

Unplug and jump the ac low pressure switch with a paperclip - if compressor comes on either system is empty or switch is bad. (switch is between the ecm and the ccm - so direct power to compressor does not go thru it)

Unplug compressor relay and swap with same part number relay found in another position (if available ) or use a jumper wire (with relay out) between terminals 3 and 5 where the relay plugs in to send power directly to the compressor. Does compressor come on when jumped at the relay plug? If so does the low side pipe get cold?

Check fuse fuse b2 and fuse c5 for the ac compressor relay.

The ECM has the final say if the compressor gets power - engine too hot, too cold outside - ac compressor will not come on.

Edit: Sorry just noticed 7/8 is an ac pressure switch also - (located in front of the ECU box) for either high or low pressure cutoff or fan turn on.

 

Thanks for posting this Hoonk, I was going to do the same thing but you saved me the trouble!