chuckbear Posted September 5, 2015 Report Share Posted September 5, 2015 The front unit of my Coleman Mach series 13.5 BTU Air condiitioner will no longer work in the Automatic setting. It switches to what appears to be hi cool, even when I set the thermostat to 90. Any thoughts? Chuck Link to comment Share on other sites More sharing options...
Ray,IN Posted September 9, 2015 Report Share Posted September 9, 2015 My first thought is to inspect the wiring connections for corrosion, loose, broken, etc. Link to comment Share on other sites More sharing options...
LFDR3116 Posted September 9, 2015 Report Share Posted September 9, 2015 We have 3 settings used on our thermostat to operate the AC normally. Cool, off, or Heat , Fan speed Hi or Lo, and Fan on or auto. The normal settings are Cool/ Hi/ Auto. We have found that with the sun heating up the outside wall where the thermostat is located, sometimes it is 75 inside, but we have to turn the thermostat up to 90 or above to get the AC to shut off. Once the sun moves past the point where it's shining under the awning and on the outside wall, the thermostat and A/C become more accurate as far as temps and the unit running. Link to comment Share on other sites More sharing options...
chuckbear Posted September 9, 2015 Author Report Share Posted September 9, 2015 Thanks but that isn't the problem. We're in total shade. The rear unit works perfectly. Only the front doesn't and only the auto setting is not working. Chuck Link to comment Share on other sites More sharing options...
LFDR3116 Posted September 10, 2015 Report Share Posted September 10, 2015 I'd try a new thermostat. Our rear AC came on and ran fine, but wouldn't shut off when set temp was reached, only when we used the "off" position. Looking inside the thermostat for loose wires, corrosion etc, it looked like brand new inside, there wasn't even any dust. DH took a long shot and replaced the thermostat and it works just fine now. Try the inexpensive solutions first. Link to comment Share on other sites More sharing options...
DaMechanic Posted September 19, 2015 Report Share Posted September 19, 2015 Sounds like the thermistor is shot in the stat. Buy a new one, because there are a LOT that are only available as lots of at least 5000. Link to comment Share on other sites More sharing options...
chuckbear Posted September 19, 2015 Author Report Share Posted September 19, 2015 Sounds like the thermistor is shot in the stat. Buy a new one, because there are a LOT that are only available as lots of at least 5000. Â If I knew what that is, I sure might replace it. Of course if I were an expert with air conditioners, I wouldn't need to ask questions. Chuck Link to comment Share on other sites More sharing options...
LFDR3116 Posted September 19, 2015 Report Share Posted September 19, 2015 A thermistor is a part for the refrigerator. Don't know if there is something like that in a thermostat, but I think DaMechanic is telling you to replace the thermostat. Link to comment Share on other sites More sharing options...
DaMechanic Posted September 19, 2015 Report Share Posted September 19, 2015 Any electronic temp control has a thermistor. Basically it change either voltage or resistance dependant upon tempurature. If you pull the cover off and take the clearest pic possible, I can circle it in a graphics program for you. Here is a typical generic one:http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_207037_-1 This is actually one of the big ones. lol That head is the size of a nitro pill. Â EDIT: If you can solder, it'd easy-peasy to replace. The problem is figuring out the correct value. Â Â SECOND EDIT: Actually, just replace the stat. This could happen if you hook the wrong one up....http://youtu.be/77ARIvt9RrE Link to comment Share on other sites More sharing options...
chuckbear Posted September 19, 2015 Author Report Share Posted September 19, 2015 Here is a photo of my AC controls. Chuck  Link to comment Share on other sites More sharing options...
coachmac9 Posted September 23, 2015 Report Share Posted September 23, 2015 Chuck, I have the same control unit in mine and have also started having a problem with the slide that controls the front AC...my problem is a little different, in that the lever or contact the lever operates must be wearing out and when I put it in the off position the little green light shows it to be still on. I can wiggle it a little and it goes off but I foresee the problem getting worse. I posed the question in another forum (on this board) of how easy it was to just replace the whole thermostat as a unit and most replied that it was a fairly easy job...that is probably what I will do when I find one that will take its place...I am also a member of the Discovery Owners Assc. and their forums are extremely helpful for just about any problem...I will post the problem on there and see what kind of results I get...I'm pretty sure we arent the only ones with problems with that control unit wearing out. I will be glad to pass along any thing I find out from the other forum. Link to comment Share on other sites More sharing options...
chuckbear Posted September 23, 2015 Author Report Share Posted September 23, 2015 Chuck, I have the same control unit in mine and have also started having a problem with the slide that controls the front AC...my problem is a little different, in that the lever or contact the lever operates must be wearing out and when I put it in the off position the little green light shows it to be still on. I can wiggle it a little and it goes off but I foresee the problem getting worse. I posed the question in another forum (on this board) of how easy it was to just replace the whole thermostat as a unit and most replied that it was a fairly easy job...that is probably what I will do when I find one that will take its place...I am also a member of the Discovery Owners Assc. and their forums are extremely helpful for just about any problem...I will post the problem on there and see what kind of results I get...I'm pretty sure we arent the only ones with problems with that control unit wearing out. I will be glad to pass along any thing I find out from the other forum. I've noticed the same issue with ours, but for now, it's not a problem. The light stays on but the unit switches off and if I move the slide just a little, it goes off. I did swap the front and back sensors and the issue moved with it. So for now, I have ordered a replacement sensor for the front unit. Once it arrives, I will replace it and see if that solves my problem. A complete replacement might be down the road but I'm hoping this will fix things for now. I'll let everyone know. Chuck Link to comment Share on other sites More sharing options...
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