Good morning, working on my daughters 2000 Civic, hooked up my a/c gauges, installed 1 24 oz can of 134a, pump not kicking in, 70 lbs on low side should be enough for pump to engage, condenser fan running, a/c switch light working, fuses all good, heading back out to my shop to check voltage on red wire at compressor with the vehicle running, will also check the continuity of the coil while I'm there...any other suggestions would be greatly appreciated, thanks...simers

 

Some background on why you decided to add R134a to the system would be helpful.

If you unplug ECU connector A, turn key to ON(II) [engine off], and ground ECU connector pin A17, does the compressor clutch engage/click?

 

When I put my manifold gauges on the system, it was holding pressure, but the vehicle sat for three years, and also endured three engine swaps, after my diagnosis it became apparent to me that there was no voltage reaching the compressor, a little rewiring, and all is well, thank you for your response Ron, system is A-OK....simers..

 

You may be able to help others in the future by posting the exact problem and your solution.