2000 Escort SE 2.0 A/C help needed!

[asknight]

Hi, I have a 2000 Escort with A/C troubles. I've checked the following and they checked OK.

1. R134A pressure/levels.
2. Fuses.
3. Cycle switch on drier.
4. High pressure switch.

* 5. I checked CCRM and found fried WAC relay. Replaced relay and reinstalled unit. Received +12V on pin 21/23 but not pin 22. I then replaced the "repaired" CCRM with known good unit with identical part #'s from car with working A/C.

I am still getting +12V on pin 21 and 23 of CCRM, but not on pin 22. There are no error codes being thrown and the idiot lights are staying off, yet the compressor still fails to cycle on.

Can you guys tell me if there is anything else I need to check such as hidden relays, etc, before I take it to the dealership for compressor test/replacement?

[Selectron]

My Escort doesn't have A/C so I've never worked on the system, but I was looking at a wiring diagram and I can see a few more checks that you might make before having the compressor tested.

If you have 12V at pin 23 then current should be flowing to the A/C clutch coil - it flows from pin 23 to the coil, returning to the CCRM on pin 16. It then flows along a PCB track within the CCRM and exits on pin 15, which is a ground connector. I'd check the following:

• Voltage across pins 16 & 23 (black lead to 16, red to 23) - you should have 12V
• Voltage across pins 15 & 23 (black lead to 15, red to 23) - you should again have 12V
• I'd then switch the ignition off and detach the CCRM connector. Ignore the CCRM and turn your attention instead to the connector - measure the resistance through the clutch coil loop between connector terminals 16 and 23.

And just some detail on that in case you're not sure what I mean. Switch the meter to the resistance (ohms) range and firstly just check the resistance in the meter leads themselves by touching the probes together - that will likely be around 0.5 ohms. Then measure the resistance from terminal 16 to terminal 23 of the connector - it doesn't matter which way round the leads go - what you're doing is measuring the resistance along the wire to the coil, and through the coil, and back again along the other wire. Unfortunately, I can't see a resistance value specified for that coil, but I'd guess it's going to be fairly low. You don't want to see a short-circuit, nor an open-circuit.

If the loop is intact with no short-circuit present, then I'd plug it back in and my last check would be to measure the voltage at the terminals of the clutch coil, or as close to it as I could get if it isn't readily accessible. The reason for that is, that just because you have 12V across pins 16 and 23 of the CCRM, that doesn't mean you have 12V across the coil terminals - you could have a voltage drop along the way on bad wires or connectors, leaving less than the full 12V available at the coil.

Edit: You might also check that pin 22 is being correctly switched by the PCM. With the A/C on, pin 22 should be 0V and pin 23 should be 12V, which we already know they are. Upon switching the A/C off, pin 22 should rise to 12V and pin 23 should fall to 0V. That would be worth checking just so you know the PCM is responding correctly and the relay isn't just feeding a permanent 12V out at pin 23.

[asknight]

Selectron, thanks for the reply. I'll be following your steps in testing the CCRM/connector in a few minutes.

After I posted my initial questions yesterday, I went back out and tried the "Nacho fix." I could not get the compressor to cycle on when the green/red wire from the cycle switch was wired to the blue wire on compressor. Leading me to believe it was a bad compressor/clutch. However, the compressor would come on "full time" when the blue wire was connected direct to battery +12V, so I'm back to troubleshooting wiring/CCRM issues as the "check engine" light came on solid when the compressor was wired direct to battery +12V.

I'll follow your steps and report back with my findings... thanks again!