I have a Coleman Presidential 7670 furnace in a mobile home. customer said it came on a couple of times by itself. I ran new wire, fan won,t shut off. Replaced fan switch, fan still won't shut off....
Brian, it sounds as if possibly the fan relay is stuck however, if the fan will not shut off I would suggest the following, Follow the wires from the fan to the relay on the relay disconnect the fan wire there and see if the fan shuts down if so there is the problem. If not you possibly have a short in the thermostat wire What can be done is take a small section of thermostat wire and disconnecting the existing thermostat (red 24 v power feed, green, is fan motor control, yellow is compressor control, white is heater control,) once you have disconnected the existing thermostat wires take the short peice of wire and connect it to the terminal block, once this done the other end (do not hook the wiring to a thermostat have the wires bare at the ends about 1/4 inch) Manually connect the red and green wires togather and see if the fan activates. If it does disconnect the r,g wires if the fan still runs then the fan relay is stuck, if not then it sounds as if there is a short in the wiring between the thermostat and the terminal block. Also check to make sure that you have set the thermostat setting itself to either gas or electric since the newer thermostats have the option of being used as gas or electric. Good Luck on your repairs.
Dave in Texas
Sep 01, 2009 |