Hi. I have a 1996 Honda Accord EX V4. I was troubleshooting a problem with the AC compressor clutch not engaging this weekend. After confirming the compressor is good (connected it directly to the battery), the compressor clutch relay also good (swapped it with the condenser fan's relay and also a new one), and charging the AC line with r134a (thinking it could just be low pressure from an empty line), I narrowed down the problem to either the AC thermostat behind the glove box or the pressure switch.

As I was troubleshooting the AC thermostat, I thought of shorting the two grounds to see if that will get the clutch engaged. However, in the process, I mistakenly shorted the live terminal (13V) to the active ground. From there, the cooling fans (radiator and condenser fans) won't run anymore. The active ground on the thermostat is also gone. I may have blown off a component that keeps the ground lines to the fans and the AC circuit connected. All fuses are intact, though.

Anybody have any suggestions on where to look at?

Thank you!

 

Verify that you have bat v at the thermostat from under dash fuse block. Shorting this to ground should have blown the 7.5 amp fuse supplying power to A/C clutch and cooling fan relay

 

I still have the 13V on the thermostat. It's the active ground that gave in when I shorted them. All fuses are still good, specially the 7.5A fuse for the cooling fans.

 

Anyone with a wiring diagram for the AC compressor and Cooling fans?

 

Take a look at bbbind.com for a schematic.

 

What wire colors did you short on the thermostat?

 

I can't remember the exact colors (I'm at work right now and the car is at home so I can't look) but it was the line with the 13V (blue/yellow maybe) and the next one beside it (middle one), the one with the active ground (not sure if it was the black/yellow). So, basically, I shorted 13V to ground in the connector and it took out the ground line. The 13V is still there but the ground is gone.

 

The blu/yel is the 12V coming from a closed a/c pressure switch. The blk/yel should also have 12V and is not a ground. The blu/red wire is the ground through the heater control panel.

I don't have the wire order for the connector, so I'm trying to figure out what/where you need to test next.

 

I only saw one 13V on the three terminals, with the COM probe of my DVM on the car body. Since I didn't see voltages on the other two, I kept my red probe on the terminal with the 13V and checked on the other two with my COM probe. I had 13V on one (I think it was the middle) and zero on the other, so I figured where I get the voltage must be ground.

Thanks for helping me through this, by the way.

 

You are welcome, we are here to help.

To test for ground on a wire, keep one probe on the body ground and the other probe on the wire you are testing. Turn the dial on the meter to ohms to measure resistance, not sure what resistance settings you meter has. The resistance should be almost zero if a wire has ground. Let us know if each wire has 12V and also if it has ground.

One way to get a feel for open/closed circuit on your meter (set to resistance) is to have the two meter probes not touch anything. That reading would be open. Touch the meter leads together, and that would be your reading for ground. Hope this makes sense.