2002 Civic - AC problem
 

My 02 Civic recently started having intermittent AC problems. At times the AC blows cold and works fine. Other times, it will only blow hot air. There doesn't seem to be much rhyme or reason, but I think the AC may work more consistently when it's not as hot outside - late afternoons, etc.

I took the car to a local mechanic and he said that the system has a full refrigerant charge and does not need coolant. He says the compressor has one or more cycle switches that turn the compressor on and off as needed. He says he thinks one of these switches is getting stuck in the off position, preventing the compressor from functioning consistently. My mechanic says he doesn't have the diagnostic gear and/or knowledge of the system to pinpoint the exact switch, but he believes the switch may be on the compressor itself.

The mechanic suggested one of two remedies. One, let him replace the entire compressor, which he thinks will fix the cycle switch. That's a $700-800 job. Or, take it to the Honda dealer, who might be able to diagnose and fix only the cycle switch, without dumping the entire compressor. (Then again, they might want to sell the whole unit).

Does anybody know anything about the cycle switch or have advice on how to proceed? Does this diagnosis sound reasonable? I'd love to get this fixed as cheaply as possible. Knowledgeable replies are much appreciated.

I'm actually facing a similar issue here:

AC doesn't work as efficiently during the day or when the car's been parked out in the sun for an hour or longer. Even after 5-10 mins of driving around, it feels like the cabin temp is only at around 26 Deg C. At night though, the cooling's just great. Feels more like 15 Deg C.

I've gotten a few second opinions for my issue at least. One tech told me it could be the blower not fitted properly after the evaporator coil replacement job. The evaporator coil not working to it's full capacity. As it happens only during the day, there is most likely an issue that's causing cold air to leak out or get mixed with the hot air. You will most likely need to take it to the dealer and ask them to open up the entire unit and inspect it and/or do a full diagnostic.

I very much doubt if there is anything wrong with your compressor. However, you may need to have it opened up and inspected. Either way, repair bills could be high, as these dealerships just ask you to start replacing parts. I'd say, take your car to at least three different AC shops, and see what they recommend. Don't have componenets dismantled unneccesarily. (Pretty sure I spelled that incorrectly!)

Works for a while then quits when it gets hot is almost always the clutch gap. The magnet coil loses strength when hot and if the gap is critical, it will be too weak to pull the clutch plate in and engage the compressor.

Here is a map of the parts for reference:
Honda Automotive Parts
The clutch plate and pulley (un numbered parts of set (4)) should be very close to each other, though not actually touching, when the car is off. If you have a gap of more than 0.020 inches, adjust it.

Remove the shaft nut (3). You will need to stop the plate from turning, usually it works to put a screwdriver across two of the three big rivets. Slide off the plate. Find the little shim washers (6) on the shaft and remove some or all of them. Be careful if you have to poke around in there to dig them out-- the rubber shaft seal is right behind them, and damaging it will cause a refrigerant leak. Put the plate and nut back on and check that the plate doesn't drag on the pulley-- if it does, put some shims back in. Test drive.

This is a DIY solution. Most places prefer to replace the whole compressor, and get a guarantee on it from their supplier, than to fiddle with stuff like this.

^^ Sound suggestion there. Although from a personal standpoint, I wouldn't fiddle with things like that, and just leave it at the factory stock setting. Either that, or replace the mechanism/assembly. I don't believe there's any need to replace the compressor in a situation like this.

As for my issue, I think it may have been fixed for good. Took her back to the same guy who had replaced the compressor bearing and seal along with the magnetic clutch, a few months back. He inspected everything thoroughly, and said the compressor was giving off oil and carbon, which was finding it's way to the expansion valve and evaporator coil. And clogging the lines.

Full system flush and evacuation - done. Expansion Valve and Receiver dryer replacement - done. Refrigerant recharge and compressor oil top off - done. Total bill - $50.

I do seem to notice better cooling in the cabin, although the job was finished late in the evening. Will take her out in the sun tomorrow and put it to the test!

I had this problem and it turned out to be that the compressor clutch relay was going bad.

Thanks for the replies. Does everybody pretty much agree that installing a new clutch would fix this?

Also, where do I find the clutch relay? I've had that problem on other cars in the past. It would definitely be worth a few bucks to me to try that before I tear into bigger repairs.

A new clutch can be easily found at any AC repair shop that's fully equipped.

Avoid the dealers for now, as they'll most likely try to convince you to replace the entire compressor, or worse yet, might ask you to replace another component or two, along with the compressor!

I wish you the best in getting rid of your AC troubles! Cheers!

The compressor relay is in the underhood fuse box. There will be a couple of other relays of the same type in there, for example for the rear defroster. Simply swap them and see if the A/C problem persists.

"The compressor relay is in the underhood fuse box."

Does anybody know which one it is? I took a look in there but it doesn't seem to be identified in the owner's manual like the fuses.

The under hood fuse box should have a diagram on a sticker.