Long story short.....

We just had a new Rheem Gas Furnace installed in our home the other day. The Contractor is NOT finished with the install. They still need to hook up the return pipes as well as reconnect and recharge the A/C coil.

In the meantime, they got enough of the furnace installed to operate and supposed to heat until the can return to finish the job.

Before they left the furnace when through a heating cycle successfully. After they left, it started short cycling. Coming On for about a minute and turning right back OFF. We called them back. He checked some things out and said our thermostat was old and a POS and it will need replaced as well. He said he would replace it when they come back next week.

We've been on electric space heaters since.

I have my doubts about the thermostat causing the short cycling as our old furnace did not do this. A bearing went out on the squirrel cage and well as a bad blower motor.

I do know incorrectly adjusted fan limit switches can cause short cycling, but I can not find and documentation on our RGPS that shows a fan limit switch and/or it's adjustments. I'm assuming is it's in the electronic controls.

So why is short cycling and how can it be fixed ??