Mid efficient Carrier furnace that wont stop running.
I am assuming for the first explanation, the thermostat is not being satisfied. If this is the case, you may have a duct fallen off and is not heating the interior of the home. I have had several supply ducts fallen off the supply under homes in one subdivision because the original installers only duct taped the supply ducting to the headers and the duct just blew off. This happens more often than I would like to mention in attics spaces also. So if the thermostat is not satisfied look for major leaks.
2nd part, you may need to replace the themostat wire if the wires are shorting out. In particular the white wire is the normal color for thermostat for w connection for furnace control. If a white wire is shorting to any control wire that has 24 volts on it, like the green wire for the fan, red wire for the control voltage to most controls etc, the furnace will run continuously as long as the furnace is getting the voltage on the white wire. To check this out, turn the thermostat to off and check the voltage on the white wire to common. If 26 volts is present, the wire is shorting somewhere and the thermostat wire that is damaged needs to be replaced. I have seen pets, rodents, lawn mower blade damage, bad insulation problems and overdrawing components causing theromostat wire deterioration.
3rd possibility, is remote due to the unit has been installed for 10 years, but if recent addtions were made to home, the unit may not produce enough heat to heat the additional demands of added rooms. In particular, this winter has been really cold in some locals and the unit may just be undersized.
Hope this helps
Feb 05, 2015 |