PLease bear with me , because I only have basic knowledge of cars in general. I have a 1999 civic dx, and my a/c is not working properly. If it is a cool day or at night, the a/c blows cold air. But if it is hot outside.....it will blow hot air 90% of the time. I took it to have the a/c serviced, and they they said everything was ok. They checked it for leaks and it was ok. They also said it was a little low on coolant and charged it up. But nothing changed. I took it back, and they tell me that I need to make sure that I have the a/c set to "recirculation" because if not it will pull in hot air and it will take longer to cool down. I knew all of this, but i tried to make sure I went through all "procedures" to ensure proper function and...nothing. Whats really weird is, the a/c may actually blow cold air on a hot day for a day. But then it blows hot air for 3 days straight. Also, if this helps, my car never runs hot( temp. wise). Don't know what else to do or look for.

 

Make sure the fan for the A/C condenser is coming on and that the compressor is engaging when you have the air on. You have 2 fans on your Civic....one for the radiator (passenger side) and one for the A/C condenser (drivers side). If you turn the A/C on the fan on the drivers side should come on. Make sure it is working properly and consistently. If the A/C compressor is not engaging the clutch it will not compress the freon in the lines and you will have faulty A/C as well. The clutch on the compressor may be bad. Finally, if the system is up to par with freon then perhaps the switch is faulty or one of the relays that controls either the A/C compressor or the fan. The fan has a 2-pin wire connector on it. You can bypass everything and make sure it will come on. hook one wire to ground and the other to +12v....does the fan work? Does the fan work when plugged in with the A/C switch on? Now for the compressor....Is the clutch engaging? You will see the pulley turn from the belt. The clutch is on the side of the pulley....you can see it spin...sometimes it will engage and disengage depending on conditions and needs of the A/C system. There is a single red wire that goes to the compressor. In order for the compressor to work this wire should have +12v. Is it getting +12v? If not, unplug the connector on the side of the fan shroud where the red wire runs. Connect +12v to the A/C compressor....does the compressor engage? Good luck....hope this helps.

 

I'm getting a similar problem. My a/c blows cold in the morning, but by miday in traffic it blows hot until I start moving again, then it will blow cold. In traffic you hear the compressor click off but it would not come back on if i'm siting in traffic.

 

Sounds like you are short cycling. Check your freon and make sure you're up to capacity.

 

I couldn't have said it better

 

thank you.

 

On my way home from work yesterday, my a/c blew cold air for about 10 min, and then hot as hell air for the rest of the trip. I did check to see if the "compressor" fan came on when I turned on the a/c and it did not. Also, a neighbor is outside at the same time who happens to be a mechanic. He works on diesel truck engines and tell me it it looks like a problem with a "high pressure switch". Also, keep in mind that I have not had a chance to go through the suggestions that you guys have given except for checking the fan. Does the neighbor diagnosis sound logical? Also, like I stated in my op, I have recently had my freon recharged or filled up(what ever you call it). One last thing......on my way to work this morning with 70 degree temp, a/c blowing cold as ever.

 

He could be right because if it has Freon than his suggestion is logical it can be the relay that is not sending signal to the compressor an easy way to check this is the compressor it only has 1 wire.

Jump power to the compressor directly if you see the it kick on and have cool air then yes it is possibly the relay if not its still something electrical. There are few parts that go to the A.C. so start with the simple ones first.

 

Please help! MY DAUGHTER HAS A HONDA CIVIC 2002 (I think) and the actual works and then starts blowing hot air. No problems found with the compressor and Freon is ok.

 

Okay, that is exactly what my honda accord is doing, so what is the answer, or is this is trick to get me to sign up. Thanks

 

 

I really like the tensioner belt answer, I would like to add that in can also be the a/c blend door actuator or flap door actuator. Does it blow hot through all the vents or just certain ones? Anywho I didn't see anybody mention they actuators so I decided to mention it. If the problem hasn't been fixed, hope this helps.