Hello I'm somewhat new here and having some a/c issues. I have a 1996 Honda Accord LX 2.2L. My issue is the compressor is not kicking on, when i jump it manually from the battery it works and it worked long enough for me to check my pressures with manifold gauges which checked out good. So here is what i have found. When i push the "A/C" button the condenser fan kicks on and everything seems to be working except the compressor.
At the relay i am getting
12v at the white wire ---
12v at the Blk/Yel ---
4.5V at the Red/Blu wire which i thought was suppose to be a ground?
0v at red of course

Checked pin a17 on pcm and am getting 4.5v back probing with ac and car running.
Relays did not act differently when i switched them and condenser fan works right with both relays.
When i unplug the a/c pressure switch while a/c is "on" the fan cuts off which leads me to believe it is working correctly,same with thermostat behind glove box.
Thanks for the help!

 

I would check the field coil to see if it engaging the clutch. Do this with the car off. There is a single wire connector that comes off the compressor that you need to unclip. Run a jumper wire from the positive terminal of the battery to the connector wire that goes to the field coil single wire (note it is a connector and not the screwed on wire which is the ground). Make contact between the battery and the single wire connector that goes to field coil. If the coil is good then you should hear it click if not then it is bad, unless you did not make proper contact. If you hear it click then you can remove the wire, connect your pressure gauges, start the car and jump to that wire again and see if the pressures change and the A/C works. If it does then you have confirmed that the compressor is good and there is an electrical issue else where.

Note that if the clutch engages and everything electrical seems to be working fine then it is likely a bad expansion valve or the condenser. Don't go throwing parts at this as it is something that needs to be diagnosed first. Good luck.

 

From your description, you're not getting a ground signal from ECM to energize the compressor relay. I would be careful measuring voltage on the red.blu wire. I've heard claims that it is possible to damage the ECM.

The ECM senses when Red//wht is grounded by closing AC switch, AC pressure switch, AC thermostat, and blower switch. If this circuit is open, the ECM will not enable the compressor. However, condensor and radiator fans coming on suggests that all above are closing since they depend on same ground path. Suggest checking that red/wht at pressure switch is going to ground when AC is commanded on. You could also check pin B5 at ECM for ground.

Finally, a substitute ECM may be necessary.

good luck