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  • car AC repair

    I know there are a lot of auto guys here, so maybe you can help!

    My car's AC unit crapped out. I can still get the fan to run, but no cold air. Lots of hot air blowing though

    The unit worked fine last week, and then stopped working, and then worked again for a day. Now, broken. I am not very confident with auto repair, but thought maybe it could be the relay. Is there a way to test the relay to see if that is the problem? Or is there another way to ID the problem without a set of pressure guages? The mechanic charges a 100 bucks just to diagnose, so if it's the relay, I could save a bundle. I pulled the relay and it is clean, no corrosion. The car is a 2003 Toyota Corolla.

    Thanks guys!

  • #2
    Re: car AC repair

    when the car is running open the hood and look at the center of the AC compressor and see if it is turning?

    if it is then most likely it is a internal problem with the AC system, (freon, compressor, or some other component or internal problem), if it is not turning, then I would check to see if power is getting to the clutch on the compressor, if if power is getting to the compressor then I would suspect the clutch or coil, but if not (and there could be a low pressure switch that shuts off the compressor), some electrical problem,

    there is a number of Utube videos on that model http://www.google.com/search?num=100...1c.H9EX584qJ0o

    the two videos seem to indicate a relay problem is common, and show which one it is,

    http://www.youtube.com/watch?v=oBPUM...eature=related

    http://www.youtube.com/watch?v=-Q95ZuA7x1o

    I do not recomend swaping the horn relay like the one Utube says, but it would be at least an indicator, to that it was the realy,
    Last edited by BHD; 08-31-2012, 07:35 PM.
    Push sticks/blocks Save Fingers
    ~~~~~~~~~~~~~~~~~~~
    "The true measure of a man is how he treats someone who can do him absolutely no good."
    attributed to Samuel Johnson
    ~~~~~~~~~~~~~~~~~~~
    PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

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    • #3
      Re: car AC repair

      Good advice from BHD, YouTube has some very helpful videos. If it stopped blowing cold I would lean towards a loss of refrigerant, but you said it got cold again which suggests an electrical problem? There are ways to "jump" out the relays and power the AC which if it blows cold with the clutch engaging tells you it's not refrigerant loss. Depending on make and model other things come into play. My 1997 Ford Explorer is known for problems with the "blend doors" which direct and mix air from the heater core or AC to the proper place. When they malfunction or break, even if the AC is working the cold air won't reach the cabin. My 1999 Ford Explorer had no AC because the engine was running hot and told the computer to power down the AC unit, once the thermostat was changed and the vehicle ran cool the AC kicked in. AC diagnosis and repair can be a real pain! Good luck and let us know. Frank

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      • #4
        Re: car AC repair

        I personally am a bit wary of some of the Youtube stuff - some good stuff in there along with a lot of hack stuff - as long as you know what the correct ones are to watch....

        That said back to the original question - if it stopped cooling and then started cooling again to the level it should do, I don't think it sounds like a leak. Most likely it is a problem with the electrical system. If you can see the condensor fan running then the only other possible suspect is the clutch coil or related wiring/control.

        Some if not all OBD2 vehicles can report a fault by monitoring the return current from the coil and light up the MIL if it detects a problem. Since this is an 03 vehicle is will be equipped with OBD2.

        Unfortunately for servicing a/c you almost definitely need a manifold gauge set. It tells you a lot of things of the state of the refrigerant. If you cannot purchase one maybe an auto parts store in your area may have it for loan. Or you could possibly purchase a cheap Harborfreight set. I'm not sure how good they are - I myself own Robinair gauges.

        You could try to find the connection to the clutch coil and monitor with voltage with a multimeter (hopefully you have that) and see if you can see 12V when the a/c is turned on.

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        • #5
          Re: car AC repair

          Just for the record I am Leary of most you tube stuff as well,

          but I think one can tell most of the time if some thing is correct, and if the person talking is knowledgeable of the subject,

          both you tubes I posted show the same relay, and where it is, yes both were kinda hacks,
          but if pulling and taping the relay and replace it, gets it working again for a few Hrs, could make the trip home on a vacation a lot nicer, I would replace, if it was the issue,
          and from what I could search out it looked like a likely possibly and most like one of the few consumer replaceable parts that could be easily tested by one with minimal tools and or skills,
          unless one has some experience to start to track down the wiring harness and start testing for voltages and so on may be beyond one scope of skills, (and if they have the knowledge/skills most will not be asking how),
          Push sticks/blocks Save Fingers
          ~~~~~~~~~~~~~~~~~~~
          "The true measure of a man is how he treats someone who can do him absolutely no good."
          attributed to Samuel Johnson
          ~~~~~~~~~~~~~~~~~~~
          PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

          Comment


          • #6
            Re: car AC repair

            You can always put a call into Click and Clack.

            Comment


            • #7
              Re: car AC repair

              Slightly OT but as far as the Internet the good come with the bad. Lots of good and bad info out there. Over time I've found that specialty forums such as this with knowledgeable regulars is much better than some of the general forums out there. I don't visit some forums anymore since a lot of the people who try to help know less than the people asking the question. But I agree - most should be able to figure this out but in some cases people may end up taking bad advice. I personally would never attempt to help out in a subject matter that I knew little about but some people think it's cool to help with little knowledge on the subject.

              Many of the specialized forms have an equivalent Plumber Rick I have preferred forums for things like stoneworking, metalworking, auto repair etc and most of them are very good.

              So on the subject of other forums I would suggest this one to the OP as there are auto a/c mechanics on there that can help. I've used this in the past. Again this may be me but I like to understand how the thing I've fixing works so if you want to understand refrigeration theory there are some good articles on there and other sites.

              Automotive Air Conditioning Bulletin Board • View forum - A/C Questions and Opinions

              Comment


              • #8
                Re: car AC repair

                Okay, thanks for all the replies! I did a bit of investigating, and found out that the clutch (the disc attached to the compressor, right?) is not turning when the engine is on, and the AC unit is on high. I can spin the clutch with my hand, so it is not seized. The fan in front of the RAD comes on when I call for AC.

                The light is solid green on the AC button, and I can hear the engine rev up a bit when I turn on the AC (still blows only hot air). I pulled the AC relay, and it appears clean and corrosion free. I did not swap it for the horn relay, as I am worried I will damage something.

                I also checked all the accessible electrical connections for corrosion, but they all seem really clean and are well protected.

                So I am still unsure of the real problem. I hope the compressor is not toast...

                Comment


                • #9
                  Re: car AC repair

                  one other easy check would be the AC fuse, and see if it is OK.

                  you could read this over, 2003 toyota corolla: ac compressor..engage..light stays..low side - JustAnswer
                  the guy answering the questions sounds like he knows the systems,
                  Push sticks/blocks Save Fingers
                  ~~~~~~~~~~~~~~~~~~~
                  "The true measure of a man is how he treats someone who can do him absolutely no good."
                  attributed to Samuel Johnson
                  ~~~~~~~~~~~~~~~~~~~
                  PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

                  Comment


                  • #10
                    Re: car AC repair

                    Relay
                    Pressure Sensor
                    Coolant Leak

                    Comment


                    • #11
                      Re: car AC repair

                      Well it was the relay. I swapped out the horn relay to check the ac relay (I was told it would do no damage as they are both 12 V), and this was the problem. The ac is running with the horn relay in place, and I have a part on order to pick up tomorrow at noon. Apparantly, the relay has been a problem with my model Toyota.

                      Thanks for your help guys - much appreciated.

                      Comment

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