The gas burners turn themselves off when the house reaches the set temperature, as they should, however, the fan stays on, but the burners do not turn back on when temperature falls below the thermostat setting. I can only get the burners to go back on if I turn off the power to the furnace and switch it back on. The igniter seems to be fine.
2007-02-19 03:24:41 · 8 answers · asked by Lou S 1 in Home & Garden ➔ Maintenance & Repairs
sounds like the control board. when your shutting off the power your basically resetting the board, if it was a fan limit the fan would not come on at all, unless your furnace is very old you wont have a thermocouple and you did state that your ignitor was fine. depending on the model of furnace you have the board will cost between 100 to 250 dollars.
i have a carrier and the board for it was listed at 269.00
2007-02-19 04:26:53 · answer #1 · answered by RUSSELLL 6 · 0⤊ 0⤋
This question is four years old but I just solved this problem on my own 1997 Rheem Criterion II air handler. As several others suggested, the problem was poor air flow triggering an overheat fault. My first try was sliding the analog TS heat anticipator to 1. No luck.The purge fan came on, the igniter lit the gas, but it flamed out after about 10 seconds. The squirrel cage fan at the bottom came on and continued to run while the start sequence cycled several times, followed by system shutdown. I also have a Honeywell analog TS, just replaced. I started tearing down and here's what it turned out to be: THE A/C CONDENSER FINS WERE CLOGGED! The A/C condenser is stacked on top of the furnace heat exchanger. Since I'm not an A/C guy and did not want to dc the freon line, I pulled the gas burner unit and purge fan below the condenser, worked the heat exchanger out, dc'd the bottom squirrel cage fan and slid it forward so I could look up from the bottom plenum to see the A/C fins at the top of the air handler. The clogged aluminum fins were obvious. This 17-year-old condenser had never been cleaned and had accumulated lots of dust over the fins on the underside, apparently from filter/unit leaks. The fix was to gently clean the condenser coil aluminum fins from below with a green scotchbrite pad (up-down), followed by a thorough vacuuming of the entire unit from condenser to plenum. I cleaned all sensors while reassembling in reverse. After reconnecting the power everything worked fine. Unit breathing OK and high temp limits happy!
2016-05-24 09:00:43 · answer #2 · answered by Anonymous · 0⤊ 0⤋
it sounds like the fan/ limit control. Without knowing the age of the furnace I can't get too specific- but if you look in the furnace there is a device mounted to the heat exchanger behind the gas valve that controls the fan based on the temperature of the heat exchanger.
If it is over 10 years old it could be a silver box with 4 wires coming out of it. If it is newer than 10 years it would be a brown rectangular device with two wires attached to it.
2007-02-19 03:42:44 · answer #3 · answered by johntindale 5 · 0⤊ 0⤋
Check Your Filters It Could Be The limit Switch Not enough Air Flow Thru Furnace.
2007-02-19 04:20:52 · answer #4 · answered by bob r 4 · 0⤊ 0⤋
if its a new furnace it has two fans and one fan exhausts all the carbon monoxide out the vent tube after the burners shut down!! the other fan runs until all the heat has been used in the furnace and directed to your house!! if its older id agree to the fan limit switch if it keeps running so long that it starts blowing cold air! other than that i would say you have a faulty thermocouple which detects the temperature in the furnace and tells the burners when to fire up! age of the furnace is important !! if its new they have an electronic module in them that acts as a main cotrol and switches back and forth between furnace and a/c if you have central air!! start cheap ( thermocouple, fan limit switch) things that are easy to fix!! other than that call a professional hvac company!!
2007-02-19 04:01:28 · answer #5 · answered by joe k 2 · 0⤊ 1⤋
When you turn off the power and back on and the igniter comes on can you hear the gas valve click ? If so, you are getting power to the valve when you should but it is not opening to let the gas through. It may be bad. That's what mine was doing. I replaced the valve about two weeks ago and it is working fine now.
2007-02-19 05:42:27 · answer #6 · answered by robert b 3 · 0⤊ 0⤋
Not knowing what model the furnace is makes it impossible to give you an answer. If the motor (fan) keeps running it is not shutting off as it should when your heated area reaches setpoint. You shut it off when you turn off the power so I would look in that area.
2007-02-19 03:35:24 · answer #7 · answered by Anonymous · 0⤊ 0⤋
replace the thermal coupler
2007-02-19 03:28:39 · answer #8 · answered by bill.2933 2 · 0⤊ 1⤋