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View Full Version : How do I determine if it is the furnace or the thermostat that is bad?


ooonie
Mar 6, 2008, 04:45 PM
I have a 0960 Maple Chase thermostat and a Carrier furnace. 16 years old. It will not stay on. I push the reset on the thermostat, it comes on but does not stay on. It comes on in the morning as set sometimes,not every morning. I also push the reset button on the furnace and flick the on/off switch. It comes on but will not continue to run. I changed the filters, the ignitor has been changed 3 times, electronic board changed in 2004. I am freezing. If I need to replace the thermostat, what do I look for, brand wise. Also, in resetting the thermostat, holding down the button to change time, does not move at all. New batteries installed. Thanks for any help you can give me. Oonie

hvac1000
Mar 6, 2008, 05:08 PM
Honeywell is my recommendation.

DaPlUmBeRGuY
Mar 6, 2008, 05:52 PM
I have a 0960 Maple Chase thermostat and a Carrier furnace. 16 years old. It will not stay on. I push the reset on the thermostat, it comes on but does not stay on. It comes on in the morning as set sometimes,not every morning. I also push the reset button on the furnace and flick the on/off switch. It comes on but will not continue to run. I changed the filters, the ignitor has been changed 3 times, electronic board changed in 2004. I am freezing. If I need to replace the thermostat, what do I look for, brand wise. Also, in resetting the thermostat, holding down the button to change time, does not move at all. New batteries installed. Thanks for any help you can give me. oonie
I would consider checking your thermocouple , as well as checking the wiring going to your furnace (to/from wall thermostat?)looking for any frayed or dis-connected wire(s)?
Also make sure your gas valve is fully opened ! If gas pressure is non suffice this can cause the unitrol to automatically shut off ! Test breaker turn breaker off and back on ?

THE RUN DOWN:
1). REPLACE THERMOCOUPLE
2). CHECKING WIRING IS CORRECT IN THERMOSTAT
3). REPLACE THERMOSTAT WITH A MORE COMPATIBLE UNIT
IF ALL FAILS CALL A LOCAL HVAC TECH AND ASK FOR A SYSTEM CHECK UP , AND WHEN HE GETS THERE TELL HIM THE HEATER JUST STARTED ACTING UP LAST NIGHT ? AND SEEMED TO KEEP SHUT OFF ?

GOOD LUCK

T-Top
Mar 6, 2008, 07:36 PM
With it being intermittent its hard to say if its thermostat or equipment problems. Is this hot surface ignition or spark ignition? 90%(vented with pvc) or 80%(vented with metal)? Some of the older spark ignition furnaces of carrier would get sluggish when the 3 or 2 wire pilot assembly got dirty. When you reset your thermostat you reset the call for heat on the control board of the furnace all so, it lets the furnace get a second chance to start after killing the 24v on the W circuit.If it was a major fault with the furnace you would have to kill the main power to get it to reset.