Recently purchased a complete A/C kit with a new compressor, condenser, drier, evaporator, expansion valve, as well as new gaskets for every connection. Put it all in my 1994 Honda Civic DX Hatch (However, has a complete wiring harness from a 1995 Honda Civic EX Coupe, as well as a rebuilt D16z6 and manual trans).
Using a manifold gauge set and a vacuum pump, I pulled a vacuum on the low and high-pressure lines and letting it sit for a night, there were no leaks. So I turned the engine on and let the car get to operating temp, turned on the A/C on the climate control and fans on full, and used the gauge set to refill the low-pressure lines with refrigerant. All was well, pressure was building in both, but the compressor never kicked in.
Here's the problem:
- Checked the voltage for the plug going to the compressor, and there was nothing when the engine was running and A/C button on.
What I've done to try and trace it:
- I checked the two relays beside the condenser and both click.
- I checked the 20A condenser and compressor fuse in the under-hood fuse box and it looked good, replaced with a new one just in case but still nothing.
- Jumped the pressure switch connected to the condenser, and still nothing.

So it's obvious there's something wrong in the wiring that is not sending a signal to the compressor to engage the clutch. I can't find any wiring diagrams for the A/C system, wondering if anyone has those diagrams, or may have some insight to what the problem is?

EDIT: Found a diagram, will start tracing the power wire for the compressor back, if anyone has recommendations please let me know.

 

Ok so done some testing. First I wanted to make sure the relays were good. Using this relay test, I confirmed that both relays have continuity when supplied 12V and a ground.

So next, I checked the power that is supplied to these two relays, as well as their grounds, using this diagram.

Starting at the compressor clutch relay: 12V coming from the white terminal, 12V from the black/yellow terminal, a ground from black/red, and nothing for red.
For the condenser fan relay: 12V coming from the white terminal, 12v from the yellow, 12V from the yellow/white, and a ground for the blue/black.
I'm not an expert with electrical stuff, but it seems to me that both relays should be working when the ac is turned on, but they aren't. No power to the red wire for the compressor clutch, and the condenser motor isn't turning on. Anyone know whats going on?

 

Voltage from the compressor relay does not reach the compressor clutch coil on the red wire. Use your multimeter to check whether the red wire has an open (break) somewhere between the relay and the compressor clutch. If so, run a new wire to fix the problem.

 

Okay, but it does, it goes to a connector to connect to the compressor. If I jump the compressor clutch relay, there is 12V to that plug with the red wire, and if I plug that into the compressor, the clutch engages. The problem I'm having is with the relays, as they act perfectly normal off the car with a car battery and a multimeter, and when jumped both relays have continuity and no resistance. I don't want to replace the relays unless I'm absolutely sure that's whats causing this problem.
Here's what I'm getting from the two plugs going to the relays, left being the condenser fan, right being the compressor clutch. When the A/C is on, here's what I'm getting from those plugs.

 

When you turn on the A/C with both relays installed, the compressor clutch does not engage. Correct?

But when you turn on the A/C with both relays installed, does the condenser fan run?

 

Neither the compressor clutch nor the condenser fan work when connected to the relays. Of course, they work when jumped, but not when the relays are installed.

 

The A/C thermostat and the heater control panel control both the fan and clutch. Test for a bad A/C thermostat (no continuity) and a bad heater control panel (failure to supply ground to the Blu/Red wire).

 

I really appreciate your help, was gonna do that, but somehow I managed to fix it. I ran my car with the relays unplugged, and jumped the power to the compressor clutch, and got it working, but the engine died after a minute. I then plugged the relays back in, and started the car back on and turned the ac on and it all worked as it should. So I continued filling the low-pressure side with refrigerant until I got to 19oz, and it blows cold. Even my mechanic friend doesn't know how jumping the compressor worked but all is well now. Thank you for your recommendations.

 

If the problem recurs (fan and clutch don't work), test the A/C thermostat, heater control unit, and the connector pin contacts.

 

If the problem returns, check my post here for the troubleshooting specific to A/C in a 94-95 Civic: https://honda-tech.com/forums/appear.../#post51642385

 

Ok so yes the problem came back, I have a sneaking suspicion that it is the solders on the ac button on the climate control, as the thermostat receives no ground to the blue/red when the ac button is pressed and fans are on.

 

 

If you go in for the repair, please take pics. All the old threads no longer have pictures, and I need to do the same repair...

Thanks!

 

My pics are not the best, I still have an old iphone, but will do. The troubleshooting guide deschlong provided was very useful, goes from front to back in helping you find the problem with the A/C system. Using the guide, everything checked out except for the climate control A/C button. To remove the climate control is kinda tricky.
Sorry if my explanation isn't the best, I should have grabbed more pics, but was not thinking about that at the time.
You have to remove the radio and I also removed the black cluster cover piece with the vents and clock. And to remove the climate control, you have to unhook the wire that opens and closes the heater core, remove I think it was about 3 screws underneath, and finally two plugs on the back of the climate control, which are also tricky to get to. Once you got the climate control out, you have to be really careful taking it apart, as the plastic may be fragile.
To get to the circuit board, you first have to remove the two lever things that control the temp and fan speed, those just pop out, remove a small screw on the bottom of the climate control, the one that would be facing the firewall if it were in the car, then you can remove the front cover plate with carefully pulling tabs around the cover, you can see two of them at the top on this pic, not my pic, and there should be one on each side also, as well as a few on the bottom

This is also a good pic, you can see the 3 mounting holes that hold it in the dash, as well as the one screw holding the front cover plate.


Then there are a few screws holding a metal bracket on the bottom, I removed that also, not sure you have to.
On the second pic, you can also see a screw on the left of where you control the fan speed, and right of the small screw holding the front cover plate. That is the only screw to remove the circuit board. Again, more tabs also need to be popped up to slide the assembly with the circuit board in it, 3 on the top, 1 on the bottom, same place as the screw. Once you get the part out with the circuit board, you can inspect the solders, here's how mine looked.

The six on the right hand side are for the A/C button. You can see that these solders are broken by the circles around the pins. I had 12 other solders look like this.

All i did was use a little flux, solder, and a soldering wand to resolder these connections, careful to not use to much solder and accidentally bridge these connections, as they are fairly close together. Definitely need a steady hand for this.

Don't worry, the weird stuff on the board is just the flux, cleans off with some electric connection cleaner and a rag, but all the connections for the A/C button, as well as the other buttons I found, are all solid now. This is what fixed my A/C system, and allowed it to kick in.

 

I just had to do the same to my car. the AC button would illuminate but the fan and compressor would only come on when I applied pressure to it. I took it out and resoldered all the points and it fixed my problems