AC blowing hot air only

[sday11]

I have a 2003 Toyota Corolla with 65,000 miles on it. Last summer, I noticed that some days, I would get in my car and the AC would just blow hot air. But, then, the next day, it would blow cold air again. It did this on and off for a month or so. Then, I didn't have the issue for a long time. Two months ago, it did it again, so I finally brought it to a shop, but of course when they looked at it, it was blowing cold air. So, they said they checked for leaks and such and everything seemed fine. They went ahead and put more freon in (though they said I wasn't too low on it). It blew cold until last Friday and now the AC blows nothing but hot air.

I live in Florida and am a student so I want to get this fixed, but I can't spend $1000 to fix this issue. I know nothing about cars and I don't want to be taken advantage of when I go back to the shop and they tell me what has to be fixed. Can anybody give me any advice on things my husband and I could do to fix or check the car before I take it in?

[sday11]

I see nobody has responded to this, so I thought I would give an update and maybe that will maybe give more clues to my problem.

After 5 days of blowing nothing but hot air, I got in my car yesterday morning to bring it to Firestone. When I turned the car on, the air was actually cool and I almost contemplated turning back, but then after driving it for 5 minutes, the air started to get warm again. So I brought it in. Go figure when they looked at it, it was back to blowing cold air and they could not find any issue with it. So, they just gave it back to me.

Now this morning, I get in and start to drive to work, it's cold air. Then after a few minutes, it started to get warm AGAIN! I had a meeting to get to so I couldn't go straight back to the shop so I drove to my office and parked. Turned the car off and then back on, and the air was ice cold! I'm so confused with this issue. Does this sound like an electrical problem? If so, what could it be? I'm so frustrated with this.

[rsirois]

Intermittent AC could be a number of problems, and most of them aren't cheap to fix. Here's a good diagnosis quide that has a section on intermittent AC.

http://www.aa1car.com/library/ac98.htm

My guess is it's either moisture/air in your AC system or a bad relay. Relays are easier to test, so you might try it first. You can usually test it by swapping an identical relay with the AC one to see if the problem clears up.

[ReTread]

Might be a damper that is opening and closing incorrectly, not shutting off air supply through the heater core. Or the temperature selector is not shutting off antifreeze/coolant to the heater core.

[Bob Shiftright]

I was also wondering about a sticking damper door.

Judging by the pictures in the $20 Haynes manual, the heater core doesn't have a valve.

Have you run through all combinations of settings in the three HVAC knobs just in case it's something like a balky servo motor or poor switch contact?

[pixystyx7]

The A/C blows cold for about 5 minutes and then continues to blow but gets warm. If you shut the A/C off for a while you can then start the process over.

My fix was the Air Conditioning Compressor Clutch Relay. Toyota labels it “M/G CLT Relay” which I guess translates to “Magnetic Clutch Relay”. Per your owner’s manual the relay is located under the hood, in a fuse box, on the driver’s side, adjacent to the fender. The Original Equipment Manufacture Part Number is 90987-02022 and can be ordered online from www.RockAuto.com for about $12. (Troubleshooting 101 has you always replace the easy and/or inexpensive items first so changing this relay is a good place to start even if you’re not sure this is the problem). This should apply to all 2003-2008 Corolla’s.