Briarhopper Report post Posted June 13, 2012 Have a Duo-Therm A/C roof mounted. The same analog thermostat operates a seperate propane furnace. Recently started cycling too quick in A/C mode. It will start and then withinn a few seconds kick off. It has also kicked off and within a few seconds started again. Along the same time noticed that the temperature setting had to be about 20 degrees warmer to operate the A/C or furnace. In other words had to set it to 85F to get it to kick on and heat (or cool) to 65F. Do these symptons point to thermostat or could there be a problem inside the roof unit? Share this post Link to post Share on other sites
desertdeals69 Report post Posted June 13, 2012 It sounds like a thermostat problem. When it goes on the contacts have a magnet that holds it together for a degree or two or three before it breaks contact. That is so it won't rapidly cycle. Share this post Link to post Share on other sites
hermanmullins Report post Posted June 13, 2012 hopper, since it affect both the AC and Heat it has to be the thermostat. Share this post Link to post Share on other sites
cobrafang61 Report post Posted June 16, 2012 The one way to know is to bypass the stat and test the unit, power enters the stat on RED, Heat is the White wire, AC is the Yellow, Fan is the Green, and a "common" "neutral" leg of control voltage may be present to power a parasitically powered stat? usually blue, Jumper the red(POWER IN) to white (HEAT) and see what happens? Share this post Link to post Share on other sites
Briarhopper Report post Posted June 16, 2012 Appreciate the feedback. At the moment, the unit has developed repairman's syndrome and I can't seem to replicate the earlier problems. Thinking maybe there was some dust in the stat or power fluctuation or other gremlin. Share this post Link to post Share on other sites
