Hi,

This is my first post and here is my issue:

My 1990 Volvo 740 Turbo's AC compressor will not turn on. I've tried bypassing the low pressure switch to no avail. I took it to my mechanic, it does come on if direct connected to battery. I've read on this and other forums that it could be the switch on the control panel but I don't think that applies to me since I have the control panel type as shown/attached.



My mechanic can bypass whatever it is, connect a toggle switch and force it on via the switch but that is a solution of last resort. Is there a separate relay in my case since the common control panel fix doesn't apply to me and if so, what is the part number or relay type that can be used for the relay if any applies.

Thanks for any assistance.

 

there's a low pressure AND a high pressure switch in series with the control signal from the dash.

disconnect the wire from the dash at the low pressure switch, connect it to a test light or volt meter, when you have the AC switched 'on', is there juice there?

 

Do we assume you put a set of AC gauges on the system to see if you have enough Freon in the system. Was the system working and just stopped.