New Thermostat Acting Strangely

stormchaser88

I have a propane furnace and central air conditioning. I have a programmable thermostat now but I bought a newer one that had more programming features. I have a 4 wire system with a common (blue) wire that has never been used. When I hooked up the new thermostat, the instructions told me that I had to hook the common wire up to it along with all of the other wires.

The thermostat worked fine with one exception, the heat works fine but when I turn it on cool, it runs for about 3 minutes, then the display on the thermostat goes blank (it's a touch screen) and then the furnace kicks on. Unfortunately, the installation guide that came with the thermostat had some troubleshooting guidelines, but everything I tried hasn't helped. I checked the voltage to the thermostat and it's fine.

I put the old stat back on and it's works fine. Any help would be greatly appriciated. Thanks.

beenthere

Brand and model number of thermostat would be nice.

Marty S.

Pretty sure you need 5 wires. R-Y-G-W-C