bryan11

The air conditioning stopped working on my 2003 Civic LX. After some work with my mechanic, we found some o-rings that were causing freon to leak out. After filling the system, it was nicely cold and then became warm again. This time, nothing has leaked out and now the compressor won't turn on.

Following some Alldata directions, we traced wires and performed tests. The end result? The directions say to flash the PCM with the latest software. If that doesn't work, the PCM needs to be replaced.

One side note is that the thermal diode looks dead above the compressor, but jumping around it makes no difference and my mechanic tells me he's never seen a need to replace it to fix AC.

What do you recommend? Are there multiple places to get the software updated? If I need to replace the PCM, what's a good source?

thanks,
Bryan

lazlong

You can only flash it at the dealer. Usually costs around $300.

2005 models (and I think 2004) should have the update. For about $100 (or cheaper) you can find a used one on eBay, craiglist, or here: http://www.car-part.com/

bryan11

Ouch. It sounds like I should buy another PCM first.

What update are you talking about? A newer program that fixes this compressor issue? I don't want to spend $300 on a program, then find I still need a new PCM and requires another dealer visit to program it.

Are there any companies that do Civic programming instead of a dealer?

bryan11

Here are the instructions followed for testing all this. I'm now at step 13/yes, so PCM work looks like the next step. If anyone has other ideas, please let me know.

A/C Compressor Clutch Circuit Troubleshooting
NOTE:
- Do not use this troubleshooting procedure if the (radiator and condenser) fans are also inoperative with the A/C on.
- Before performing symptom troubleshooting, check for powertrain DTC's. (scan the car)

1. Check the #1 (20 amp) fuse under the hood, and the #14 (10 amp) fuse under the dash.

Are the fuses okay?

Yes - Go to step 2.

No - Replace the fuse(s) and recheck.

2. Check the engine coolant temperature, throttle position, and idle speed. (use the HDS PGM-FI data list if possible)
ECT Sensor: 169 - 194 degrees
TPS: About 0.5 volts
RPM: More than 700

Are the coolant temperature, throttle position, and idle speed okay?

Yes - Go to step 3.

No - Troubleshoot and repair the cause of the high engine coolant temperature, low idle, or excessively high throttle position sensor reading.

3. Remove the A/C compressor clutch relay from the fuse box under the hood and test it.


Is the relay okay?

Yes - Go to step 4.

No - Replace the relay.

4. Measure the voltage between terminal #2 of the A/C compressor clutch relay socket and a body ground.


Is there battery voltage?

Yes - Go to step 5.

No - Replace the under-hood fuse box.

5. Connect the #1 and #2 (blue/red wire) terminals of the A/C compressor clutch relay socket with a jumper wire.

Does the A/C compressor clutch click?

Yes - Go to step 6.

No -
* 2001 model: Go to step 14.
* 2002 - 2005 model: Go to step 17.

6. Disconnect the jumper wire.

7. Turn the ignition switch ON (II).

8. Measure the voltage between the #3 (black/yellow wire) terminal of the A/C compressor clutch relay socket and a body ground.

Is there battery voltage?

Yes - Go to step 9.

No - Repair the open in the wire between the #14 fuse in the under-dash fuse box and the A/C compressor clutch relay.

9. Turn the ignition switch OFF.

10. Reinstall the A/C compressor clutch relay.

11. Make sure the A/C is OFF.

12. Turn the ignition switch back ON (II).

13. Using the Backprobe Set, measure the voltage between the #18 terminal (red wire) of ECM/PCM connector E and a body ground with the ECM/PCM connectors connected.

Wide side of female terminals

Is there battery voltage?

Yes - Update the ECM/PCM if the software is out of date (not likely) - or swap it for a known-good one and recheck. If the problem goes away using the replacement ECM/PCM (ECU) .. keep it. NOTE: If you swap ECU's, you'll need to have it reflashed by the dealership or else your car will not run. The only way around this is to get an ECU, keys, and ignition switch from the same parts vehicle.

No - Repair the open in the wire between the A/C compressor clutch relay and the ECM/PCM.

14. Disconnect the jumper wire.

15. Disconnect the A/C compressor clutch 1-pin connector.

16. Check for continuity between the #1 terminal of the A/C compressor clutch relay socket (blue/red wire) and the A/C compressor clutch 1-pin connector.

Is there continuity?

Yes - Check the A/C compressor clutch clearance, the thermal protector, and the A/C compressor clutch field coil.

No - Repair an open in the wire between the A/C compressor clutch relay and the A/C compressor clutch.

17. Disconnect the jumper wire.

18. Disconnect the A/C compressor clutch 3-pin connector.

19. Check for continuity between the #1 terminal of the A/C compressor clutch relay socket (blue/red wire) and the #2 terminal of the A/C compressor clutch 3-pin connector. (also a blue/red wire)

Is there continuity?

Yes - Check the A/C compressor clutch clearance and the A/C compressor clutch field coil.

No - Repair the open in the wire between the A/C compressor clutch relay and the A/C compressor clutch.

lazlong

update=flash (semantics)

bryan11

It's fixed temporarily. Our test of the thermal protector apparently didn't work correctly, as tonight I joined the two wires going to it and the compressor started working. The kludge part is that I ended up cutting off the protector, stripping a 1/2" of each wire to it, and using a wire nut and a bit of electrical tape to connect the wires. Never did see where the TP connects. When I order another, I might just cut off the sensor part and connect it to the existing wires.