Hey Everyone!

I am new to this forum and looking for information. I have a 1992 Honda Civic DX with the automatic transmission. My wife purchased this car in 2003 with only 28,000 original miles. It currently has 106,000 and runs pretty well.

The one problem that is driving me crazy (especially now with the heat) is that the AC doesn't work well. Listed below are the issues with the AC system.

1. When the AC is on the RPM's drop and the engine idles very rough, almost to the point of dying. When I am driving it's not so much of an issue because the RPM's are kept up. However, when I stop I have to turn the AC off.

2. The AC only blows cold when I am moving. I think it has to do with airflow, but I am not sure.

3. The AC can't blow cold once the outside air temp reaches 80+ degrees.

I think I may have two issues, but I am not sure and I don't really want to take it to a mechanic because the car is old and I don't want to put much money into it.

Issue # 1 (I think) is that I may have low refrigerant levels which is why the system can't keep it cool on warmer days.

Issue # 2 (Again I think) is that the computer/system that tells the engine to rev up RPM's when the AC is on, isn't working...but I have no idea what that computer/system is.

As you can tell I'm not that mechanical lol but I would appreciate any information or advice you all could give me!

Thanks, Patrick

 

Failure to cool when sitting still-- sounds like the condenser fan is not working. The condenser is the radiator like device under the hood that rejects heat from the A/C system. If it is allowed to overheat, pressure builds up until the compressor puts a heavy strain on the engine and also the system doesn't cool. The fan should run all the time the compressor is engaged.

After fixing the fan, failure to cool in hot weather could be a compressor clutch issue, or maybe a little low on refrigerant. Do not just add refrigerant without diagnosing further first though.

 

Thanks for the info mk378!

I just ran the car for 5 minutes with the AC on and the fan never came on.

 

Find the fan motor plug and test for voltage between the two wires in the plug. If you have power there but the fan doesn't run, motor is bad. If no voltage reaching the motor, test from either pin to ground, if both have battery voltage it's a bad ground. If no voltage at all, test the fan relay by swapping it with the compressor relay. These two relays are on a little bracket near the left headlight and the condenser. Just unplug them both and plug in the plugs to the other relay.

 

^ good reply mk, also they do make a tool that you can get that reads pressure in an A/C line. chances are if you know someone that works at a shop they will have one, it is easy to hook up to the system (two nozels High and Low) then it reads pressure under load and not. that is of coarse the next step if mk's post didnt fix the issue. ;-)

 

The fan must be working before you worry about pressure. On a Civic, the fan is not pressure-controlled, it simply turns on all the time the compressor is on.

 

correct i agree with you thats why its the "next" step

 

Thanks for all the responses! I will test the connections when I get off work tonight and report back.

 

I borrowed a voltage reader and started at the fan plug. I got nothing. So I moved to the fuse panel and I had power. Then I went to the relay and I had power. I thought about it for a minute, then started closely examining the relay plug. That's when I realized the connection wasn't good. I cleaned it well and made connected it again, and the fan worked!

When I turned the engine over and turned the AC on, the RPM's stayed up higher and the AC blew colder at idle. I really appreciate all of your help in fixing this! It's going to be in the mid 90's this weekend and this fix couldn't have come at a better time!

Thanks, Patrick