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I took my 04 Civic EX to a mechanic who did a free AC check because the AC wasn't working. He said that the compressor was working fine and that it was cold (that it isn't a freon or compressor issue) but when you turn the AC on it blows out hot air. He then said that it is either a blockage somewhere or an electrical issue and that it would be $90 per hour just to figure out what the problem was (not including fixing it).

So my question is, is there a way I can troubleshoot if it is a electrical problem such as a blown fuse (which fuses do I need to check?) or a simple wire (does anyone know where the wires for it are located?) that needs to be replaced?

I do have some wiring background so I can redo wires. I also added a small sub to my car before I noticed that my AC wasn't working and I'm starting to wonder if I messed up a wire when running the power wire for it. I ran the power wire through the hole in the passenger side floor (under the glove box) that was already there.

Thanks for your help.

 
Rep Power: 186

The chilton manual has excellent electrical drawings in it for troublshooting this problem.

I did the same thing to my 02 ex after I replaced my timing belt. I ended up breaking a wiring going to the reciever/dryer pressure switch connector. My condernsor and radiator fan would come on, but the compressor would never kick on. Warm air was blowing. I used the chilton manual and was able to successfully troubleshoot it to the pressure switch connector.

The fuses and relays are in the engine fuse/relay box. The fuse information is located in the owners manual on page 287. You'll need the chilton manual to look up the relays.

 
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Would you be able to tell me which fuse it should be? I bought my Civic used and didn't get a manual :/

 
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Those manuals didn't come with the car. I've seen 'em at AutoZone, O'Reilly, Pep Boys, and sometimes Wal-Mart in the auto section (not too many of them).

 
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A 04 Honda Civic EX doesn't come with a Honda Civic manual if you bought it new? I'm not talking about the chilton manual cause I know I would have to buy that somewhere, I'm talking about the Honda Civic manual.

 
Rep Power: 812

make sure the heater hose valve is working properly. its in the back of the engine bay where the smaller coolant hoses go into the dash. there is a cable (usually blue) going to a lever and when you turn the temp dial in the car from hot to cold, the lever should move to close or open the coolant coming into the dash. you need two people to do it. if the lever doesnt move, its stuck and the valve needs to be replaced.

make sure the compressor actually turns on by coasting at around 25mph and then pressing the a/c button. the car should start slowing down and feel like something is dragging. if there is no change, the compressor is prolly staying off.

 
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Thanks for the input! I ended up taking it to another shop for some other work and they fixed whatever problem it was. They said that they just added more freon and it has worked since then so I think the first shop knew that and was just trying to get more money out of me.