I have had an issue with this for awhile & posted it here months ago.
Well I finally have time to work on it. I need help & ideas.
I can turn on the A/C by pushing the A/C Button & turn on fan Blue light lights up. It may work for hours or ten minutes. I just charged the system R12, it had not been checked in over two years. All my pressures are good. Sight glass clear, A very small leak @ compression seal 8-10 oz in two years. (I have a Type I & II High Pressure & ASE Certs)
What happened today makes me believe I have a loose wire or bad connection SOMEWHERE.
I turned on the A/C & it started got nice & cool 34 degree closest vent to evap. Then the compressor & fans shut off & it started blowing warmer air BLUE LIGHT ON. Then the compressor started & it cooled down & was fine for an hour until I shut it off.
So does anyone have a wiring diagram for a 90 Civic LX Sedan? Or does anyone have any ideas. We talked before about the blower switch but the blue light stays on when the compressor & fans shut off. When the A/C works it will freeze you out of the front seats.
Any help would be appreciated Thanks.

 

The light is an entirely separate circuit that doesn't mean much. The circuit goes from the button to the evaporator temperature switch (can be found by removing glove compartment) to the pressure switch (on the high side line on the right side of the car, just after it turns back to go to the firewall) to the fan relays. If neither condenser fan starts, the problem is somewhere in there. Note that the circuit is "negative logic' where the button completes the ground circuit for the relay coil.

 

Thanks for the info. I guess I have some tracing to do.

 

UPDATE:
I found possible the problem. I noticed today that the compressor clutch is not always engaging. I heard this rattling noise when I was sitting at an idle. The A/C was blowing cold then I heard this rattling noise. So when I got home I checked & the clutch isn't engaging sometimes & I believe it is unlocking with RPMs.
So I'm going to try & clean between the two surfaces & see if that helps. Well I tried that & it doesn't look favorable. Looks like clutch time. But after looking it looks like a compressor, can't find just a clutch. If I have to do that I guess R134 conversion. CRAP

 

A clutch problem would have the condenser fans running but compressor not engaging. The clutch used to be sold separately. If it is simply that the gap is too large (and not anything broken) you can take the clutch plate off and remove some shim washers from the shaft.