A week ago a/c system went out on my 2000 V6 Accord. I noticed the clutch on compressor was not engaging at all but system was full of refridgerant. After watching the clutch, I noticed that if you shut the car off and then restarted it, the clutch would engage for 1-2 secs then disengage and never come back until restarting car again. Checked fuses and replaced ac clutch relay. Also jumpered low pressure switch, no luck. I then disconnected the clutch and jumpered 12 volts to the clutch and it engaged and cooled the car great.

To make question shorter, this is what I have replaced and/or did so far. The above items. Replaced expansion valve, and blew out evaporator. Replaced reciever/dryer and blew through condenser to ensure it was clear. Replaced AC Control (Automatic / Digital). Flushed system with cleaner, and finally last night I installed a new AC compressor assembly (with new clutch).

After installing each item and trying to service the system after pulling a vacuum, the same situation occurs. When starting to add refridgerant, it doesnt want to flow into the vehicle, can tries to freeze up and but it will take freon slowly. But after about a half a can it stops and relief valave open up. When this happens low side is 90-100 psi/high side 380-390 psi. I also noticed that right before relief valve opens, the engine bogs down and almost quits (actually did one time). While trying to put in first can of freon, I have clutch disconnected and jumpering 12 volts to engage clutch to help pull in the first can. I AM AT THE END OF IDEAS AND HAVE TO GET THIS FIXED FOR MY FOLKS.

One last thing, while trying to service it the last time after installing the new compressor, I noticed the neither electric fan (radiator cooling fan or condenser cooling fan) was coming on. And the car was getting hot, it didnt over heat but it was much warmer than usual. I know on most vehicles the fans should come on instantly when AC is turned. Is that true for Hondas as well, and if so could it be playing a factor in the AC problem. (as I am not sure how long they have not been working). I did check relay and fuses for the fans and also unplugged them to check for power, and did not have power at either of the fans plugs.

HELP!!!!!!!!!!!!!!!!!

 

Original problem was likely excess clutch gap preventing the compressor from remaining engaged.

Your problem now appears to be a blockage in one of your new components; receiver/drier or expansion valve. You will need to find and correct the blockage.

good lucik

 

OK, flushed entire system with cleaner and blew out with shop air then nitrogen. Put system back together, pulled a vacuum and no leaks. Went to service system with freon and this time I left ac clutch plug connected but i probed back of plug with an upholstry needle and put power on clutch to engage it when first starting to service system. however, after one can of freon, same problem system over pressurized, high on low side, high on high side.

But as stated in previous statement, neither fan is coming on when i turn on AC switch. if the AC switch is turned on and left on, if you turn ignition switch off and on, both fans will run for 2-3 seconds then shut off. they wont come back on. The same happened with AC clutch as well, it will energize by itself once you turn ignition switch but will only stay energized for a sec or 2.

So, for testing, I made sure all connections were good, checked fuses and relays, and I rigged up some jumper wires to energize the condenser fan and AC clutch by hooking them straight to battery. Started car (there is correct amount of freon in system, but have high pressures and not cooling), then i hooked up the previous made jumper wire to battery which energized the fan and clutch, INSTANTLY the low side pressures dropped to about 35-40psi (down from 110psi) and air was blowing out of vents at about 50-52 degrees F.

So AC system in itself appears to be working now less the clutch not staying engaged and Rad/Condenser fans not running. The problem with the over pressurizing appears to be linked to the fans not coming on. I have read some of the threads in DIY but if anyone has any ideas i could greatly use it. There is something that is not sending a signal to the system. Again any ideas would be great. I did notice a radiator fan timer behind dash when installing the new expansion valve, could it have anything to do with problem? Also, does Low Pressure switch on top of receiver dryer send any kind of signal to control these 2 devices. Thanks again for any help!

 

When the car is in the stock setup, does the compressor engage with the engine running? Do both fans come on?

 

no the clutch does not engage and neither fan will run in the stock setup. Like I said in previous statement, all three will energize for a couple of seconds when you turn the ignition switch on. then they disengage and will not do anything until you turn ignition switch off and back on again.

thanks for any input.

 

Unplug the a/c pressure switch. Use the continuity (or resistance setting) on the volt meter. Check that the two pins on the pressure switch read closed circuit (~0 ohms).

With the key in the II position, check for voltage (12V or maybe 5V) on the yel/grn wire for the pressure switch connector to ground (use a valve cover bolt as ground).

I would do the same test on the fan control module electrical connector.

From the manual, it looks like the fan control module is in the engine bay. Close to the windshield in the center of the car. It is a black box with eight wires going to it (grn, blk/yel, yel/wht, yel, wht, blk/yel, wht/grn, and blk). It will almost be under the cowl and on the firewall. Check for voltage on each of those wires and let us know what you find. It may be inside the car way up in the dash.

The drawing in the shop manual is not clear to me. Hopefully it is easily accessible in the engine bay.

 

Will do and let you know tomorrow. Thanks!

 

Since the system ran OK w/ jumpers, the blockage has been eliminated. There is no way for the system controls to cause a blockage. Lack of coolilng fans will cause higher pressures at idle, but not as high as yours. System will work fine w/o fans as long as car is moving.

ECM enables the compressor and fans by grounding the relays to energize. If they are not being energized, either pressure switch is open, or perhaps ECM if faulty.

We have been seeing ECM failures in earlier models (90-97), but not later models, but I'm sure it's possible.

good luck

 

I ohmed out the pressure switch and got 5.6 ohms and when I checked the yellow/green wire on pressure switch plug with key in II position, I got less than 1.0 volt. What does that tell me? Not sure if i have found fan control module yet. I did find a small black box with 8 wires going to it. It was behind dash between center console and glove box, on passenger side. It was labeled radiator fan timer control.

 

That is the part I was talking about. Just make sure you have the wire colors going to it that I mentioned.