From: Neon John <johngdNOSPAM@bellsouth.net> Subject: Re: Air Conditioner Woes...Update Date: Thu, 08 Jun 2000 01:03:53 EDT Message-ID: <393F2938.150DD7B0@bellsouth.net> Newsgroups: rec.outdoors.rv-travel Ops wrote: > Here's a follow up to our request for help on our A/C unit. As y'all > suggested, I upgraded the existing 12 guage extention to a 10 guage (30 > amp) cord and then > proceeded to turn the unit on... Nothing!! Fan runs fine but still no > air-conditioning. > Bummer!! Any other suggestions for items to check before I yank her out > and take > to RV repair center?? The unit is a '91 13,500 BTU Emerson "Quite Cool" > w/heat > strip. If there's no evidence of high current draw (lights dimming - NOT 12 volt lights!, funny growling/humming noises, etc) when you turn it on, then it is likely that the thermal overload compressor protector has failed. You indicated that you let it attempt to start for quite some time on the small cord. This means that the thermal overload had to operate every minute or so over an extended period of time. The little boogers can't take more than a few dozen cycles before failure. To check, take the cover off the AC and find where the wires enter the compressor. there'll be a bakelite lid held on with spring clips. Pop those loose and remove the cover. You'll see the three wires going into the compressor housing and right beside it will be a round bakelite device about an inch in diameter. Usually labeled with the Klixon brand. The common lead of the compressor will go through this device. If it's not physically burned up, check it with an ohmmeter. Should get continuity between the terminals. If not, replace it. Cost is cheap - $10-15 retail. Be sure to get the exact replacement. These things are designed to have similar thermal characteristics as the motor windings and are matched to the compressor model. A wide range of Klixons look alike. The part number printed on the top tells the story. If you do have continuity, then you have to look elsewhere. While you have the lid off the compressor, check it out. Put one lead on the common wire going into the compressor. This is the one that goes through the Klixon and is usually black. Measure the ohms to the other two terminals. One terminal should have about 1/2 to 1/3 the resistance of the other. The higher resistance is the start winding. For a compressor of this size, the value will be in the 2-10 ohm range. If one is open or zero ohms, bye bye compressor. Next check to ground from all three terminals. Any continuity and bye bye compressor. If you've gotten this far with no obvious problem, hook one side of your meter to ground and set it to AC volts. Have someone turn the unit on. Check the two compressor terminals for voltage. Should be near 120 volts. Check the compressor common. Should be near ground. If you have voltage on the common, check the other side of the Klixon. If there is voltage across the klixon, then it is failing under load. If you have voltage on the compressor terminals and it isn't running, probably new compressor time. Note that if the thing is locked up or the starting device is bad (cap, relay or both), the klixon will open fairly rapidly so you have to make your measurements fast. If you don't have full voltage, then it's time to work backwards. the power switch is a good place to look, as is the thermostat. On my coleman, the thermostat is very rugged but the power switch looks quite flimsy. I'd look at it first. Tracing it all out with your ohmmeter is quite straightforward. -- John De Armond johngdSPAMNOT@bellsouth.net http://personal.bellsouth.net/~johngd/ Neon John's Custom Neon Cleveland, TN "Bendin' Glass 'n Passin' Gas" |