I just bought a 2002 Honda Civic Ex Coupe. It has 117,000 miles on it. Runs great so far but the air conditioning only blows cold air for the first 15 minutes of driving, then just blows regular air. If I turn the A/C off and keep driving for awhile, then turn it back on it will blow cold again for a few minutes, then run out again.

What should I expect to hear that the problem is when I take it into a service shop?

 

My guess is the compressor clutch gap is too wide. Drive until it is not cooling, then pull over and open the hood (engine running and A/C button still engaged) and check a few things.

First make sure the condenser fans are running. Failure of the condenser fans will cause the A/C to not work in slow traffic, but it will do OK at highway speed.

Then look if the compressor is engaged. If not it's likely the clutch gap problem (less likely, a relay, switch or other electrical problem). The gap can be adjusted by removing the clutch plate and taking some shim washers out. Some places might insist on replacing the whole compressor, that's really unnecessary.

If the clutch is engaged, the next thing to consider is evaporator freeze-up. When that happens, you might even see ice on the line under the hood (the one from the firewall back to the compressor). This usually means the evaporator temperature sensor is bad.

If you find the clutch engaged, fans working, yet the lines under the hood are not cold, it could be the expansion valve. Refrigerant pressures would need to be checked to confirm that.

Since it works sometimes, you know there is enough refrigerant. Don't try to add more.

 

Update: I took the car in this morning to a service station and told them the problem I'm having. I dropped it off. They called about 3 hours later and said its fixed and ready to pick up. They said it was low on refrigerant and filled it up. $93 bill. I drove it on the highway today for a 60 mile trip. About 30 miles in, BAM all of a sudden no cold air. For kicks I left everything alone and kept driving. About 5 miles later BAM, ICE cold are starts coming out for about the next 10 miles. Then all of a sudden no more cold air. Kept doing this the entire way there and back.

I did pull over and check under the hood at one point when it was not blowing cold air. The condenser fans were working fine. When I turned the A/C off the fans stopped and when it turned the A/C back on they kicked back on. I can't really see the compressor because its so far down there, I would imagine I need to jack the car up to see the compressor, is this correct?

Any other ideas? Again the problem is that it will blow cold air for about 15 minutes, then stop, then start blowing cold again all of a sudden, then stop. Very random. It's not like it goes from COLD to Cool to Warm. It is black and white either ICE cold or WARM.

 

Check the clutch clearance and thermal protector:

 

Another Update: I drove the car home from work 20 miles or so and it blowed cold air the whole way. When I got home I let it idle for about 5 minutes while I changed clothes and it still blowed cold air. I checked the compressor and it was running. I then turned the A/C off and the compressor stopped running. I then turned the A/C back on and this time no cold air. I checked the compressor and it was NOT running.

I turned off the car and let it sit for about 10 minutes, then turned it back on and turned the A/C on, it blew cold air. Checked the compressor and it was running. I turned the A/C off and back on several times and couldn't get it to not blow cold air when desired.

So my problem has something to do with the compressor. How does the spacing of the clutch make it work sometimes and not others?

RonJ, where did you get that picture? I would like to see a larger version.

 

Click the Manuals link in my signature and download the EP3 02-03 Civic Si manual. You'll find a lot of good info in the HVAC chapter.

Also test the Thermal Protector on the compressor.

 

I could use some extra instruction on how to test the Thermal Protector. I'm not familiar with how to test for continuity.

Regarding the clutch gap on the compressor, is this common to have to adjust? Why would the gap matter if it works sometimes and not others (randomly).

 

You need a multimeter to test continuity. Do you have one or can you obtain one? If not, you can buy an adequate digital multimeter for about $15 to $20. Doing the test is pretty simple.

I believe the clutch is engaged by an electromagnet force created by a coil. If the clearance is just a bit too wide, then the force is too weak to pull the clutch in and engage it at all times.

 

Yes I have a multimeter. Instructions?

 

Set the multimeter to measure resistance (or continuity if your meter has this setting). If the meter doesn't auto range, then choose the lowest scale of resistance (e.g., 20 Ohms). Uncouple the thermal protector connector and the field coil connector. Touch one probe to the pin in the thermal protector connector and the other probe to the other end of the wire that was connected to the field coil connector. If you measure ~1 Ohm or less, then there is continuity (=good). Also measure the field coil resistance by touching one probe to the end of the field coil connector and the other probe to the metal surface of the compressor (see diagram in previous post for proper readings).