obedb Report post Posted June 29, 2016 Front A/C will not start. No display, no compressor operation, but the fan will work if I slide the switch into run. Nothing else works. Rear unit works just fine A/C, display, etc. I suspect the front electronic thermostat. They are same manufacturer. The front one has been balky for the two years we have owned the coach. Troubleshooting will be tomorrow. Unit is being readied for a late July departure. Ideas appreciated. Both thermostats probably have a shared power source. Just a guess. Share this post Link to post Share on other sites
wildebill308 Report post Posted June 29, 2016 The first thing I would do is pull the front of the thermostat off, inside is a fuse, pull that for a short time and replace it, see if that helps. I have done this a couple of times to fix problems. Good luck. Bill Share this post Link to post Share on other sites
obedb Report post Posted June 29, 2016 Thank you for the reply Bill. Tried pulling the fuse twice for first 10 minutes and then 30 minutes. When I replaced the fuse each time the digital display partially appeared and faded. My multimeter confirmed that voltage was there. Now I am looking for a digital thermostat for a Coleman Mach roof top unit. 7 wire with. a mfg. date of 0246. The search begins. Share this post Link to post Share on other sites
blakeloke Report post Posted June 29, 2016 Byron, This may seem way out in left field......but here it goes. Last summer our front air conditioner would not cool. Fan ran on low but there was no cool air. We had a mobile RV repair guy out to the coach since we were at a park and he said he could find nothing wrong with the A/C unit or the thermostat. Long story short, with a bit of research on this forum, we found if we turned off the fluorescent lights in the front of the coach the A/C would work. So, we converted all the fluorescent lights to LED and the A/C has cooled ever since! RV parts tech told us that the ballasts in the fluorescent fixtures creates interference with the thermostat. I'm an oil guy and only understand the basics of electricity but maybe someone else can explain why. If you haven't already, try turning all fluorescent lights off in the coach and reset your thermostat. Blake Share this post Link to post Share on other sites
jleamont Report post Posted June 30, 2016 ObedB, Blake made a good point that I had forgotten about, give it a try, if still no good call around for a thermostat. Don't forget Stoltzfus RV in West Chester PA, a little far from you but they have a decent inventory of parts, in a pinch I will run to them. Share this post Link to post Share on other sites
manholt Report post Posted June 30, 2016 Like Blake, would like to know, why ballast has anything to do with AC Thermostat? I can tell you all about Petroleum Exploration...dumb as dirt on electric! Carl Share this post Link to post Share on other sites
blakeloke Report post Posted June 30, 2016 Here's an article I found doing a search....Electro Magnetic Interference. http://www.lrc.rpi.edu/programs/NLPIP/lightinganswers/pdf/view/LAEMI.pdf And, here is something on this forum (one of a handful) Blake Share this post Link to post Share on other sites
manholt Report post Posted June 30, 2016 Blake, thanks. That explains why I'm getting good picture on my shop TV now that I replaced 12 double 8' Florescent with 4 double 4' LEDs. TV on Rabbit Ears. One thing that must be noted for all LED use, DO NOT LOOK AT LIGHT...it can blind you! At best, you'll be looking at spots all day! Carl Share this post Link to post Share on other sites
rsbilledwards Report post Posted June 30, 2016 It was a very interesting and informative article, who would thought of those without the technical expertise. Thanks for the post Bill Edwardsj Share this post Link to post Share on other sites
obedb Report post Posted June 30, 2016 Blake/ thanks on the mention of possible interference. We still have fluorescent light fixtures, but none were on when the failure occurred. We have a lot of new tubes to use up before I convert. Have seen Joe's conversion in his HR , but his conscience (DW) said they are expensive. They really light the interior up though. Rich sent me a link to eBay that has a carbon copy for $49.95 new in box. My guess is a dealer is selling the unit. Don't remember buying anything on eBay, but I will give it a try in a few. Share this post Link to post Share on other sites
tzeile Report post Posted July 3, 2016 On June 29, 2016 at 4:08 PM, blakeloke said: Byron, This may seem way out in left field......but here it goes. Last summer our front air conditioner would not cool. Fan ran on low but there was no cool air. We had a mobile RV repair guy out to the coach since we were at a park and he said he could find nothing wrong with the A/C unit or the thermostat. Long story short, with a bit of research on this forum, we found if we turned off the fluorescent lights in the front of the coach the A/C would work. So, we converted all the fluorescent lights to LED and the A/C has cooled ever since! RV parts tech told us that the ballasts in the fluorescent fixtures creates interference with the thermostat. I'm an oil guy and only understand the basics of electricity but maybe someone else can explain why. If you haven't already, try turning all fluorescent lights off in the coach and reset your thermostat. Blake Share this post Link to post Share on other sites
tzeile Report post Posted July 3, 2016 I have had similar experiences with the air conditioning thermostat. I found that my unit would not start if the demand temperature was greater than some differential threshold. IE If the thermostat temp showed 85, as an example, I could not get the air started if I set the desired temp more than 8 or 10 degrees lower. Could just be poltergeist but it is consistent. When the temperature drops to say, 80, I can then reduce the desired number by a corresponding degrees. So there you go! Bonehead Share this post Link to post Share on other sites
kaypsmith Report post Posted July 4, 2016 Thanks Marconi and Armstrong for introducing us to the wonderful world of RFI. Happy FOURTH OF JULY WEEKEND to all. Share this post Link to post Share on other sites
RodgerS Report post Posted July 4, 2016 Simply replacing components (standard practice at dealerships), until the system works, is an accepted RV service practice as few technicians or owners have taken an a/c class. ===================== I would recommend taking a detailed RV a/c class, as I did, before trying to do troubleshooting on an A/C system,and to build your own specialized a/c troubleshooting tool like I did. If you are able to roll out to my place in the Bay Area, I would be happy to assist. Rodger S. Share this post Link to post Share on other sites
manholt Report post Posted July 4, 2016 The difference in price is, a cooler coach, longer life and less light needed...also, use of less watts. I have nothing else in house, garage and shop now and my elect bill is way less! Happy 4th and fly a flag... Carl Share this post Link to post Share on other sites
obedb Report post Posted July 6, 2016 New thermostat installed, Front a/c working great. Share this post Link to post Share on other sites
manholt Report post Posted July 6, 2016 Byron. Great timing. It's not cold between PA. and CO ! Glad it worked out and you didn't have to take an AC Class ! Carl Share this post Link to post Share on other sites
jleamont Report post Posted July 6, 2016 1 hour ago, obedb said: New thermostat installed, Front a/c working great. Glad to hear!!! Share this post Link to post Share on other sites
blakeloke Report post Posted July 8, 2016 Great news Byron! Share this post Link to post Share on other sites
