Furnace runs OK, but blower runs again a few seconds later
Happens more when cold, as in the morning or real cold outside temps. Furnace will run & heat normally, but after it shuts down, the blower will start up a few seconds later and run for only a few seconds. Usually once, sometimes twice in quick succession. Furnace is Carrier forced air, about 18 years old. Technician states ''that is what old furnaces do'', cleaned it, checked plenum for cracks, all OK.
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Re: Furnace runs OK, but blower runs again a few seconds...
Could be a defective thermostat in the plenum.
When a gas furnace shuts down the fan(blower) will run until the plenum cools to the safe range. Usually 1 and 1/2 minutes.
Intermittent operation is a defective thermostat or relay.
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sounds to be symptomatic of a CTS (coolant temperature sensor). there are two, one is for the interior temp gauge, the other is for the ECU/PCM while both are basicalty the same part, often even the same P/N, they both do extremely different things.
This could be water in the hoses that connect to the pressure switch , they should just pull off and blow then out also blow out the pressure switch , this sound like a moisture problem with all the bad weather you h, check air filter is not blocked .
It sounds like you got a tough one there.When you say the blower starts up and then the igniter comes on are you refering to induced draft motor or main blower. The proper sequence is for the thermostat to call for heat at which point the induced draft motor should come on and run for 30-45 seconds,then the igniter should heat up for a few seconds then gas valve should open and main burner should light. After limit switch reaches set point for fan on ,blower should come on till after heat has reached thermostat setting then burner should go out, and blower run until fan off setting is reached on limit switch. If your furnace is not following this sequence and then not always doing the same thing in the same order,I would recommend that you change out board again. I have had several problems similar to this with Goodman units and all but one time installing new board solved it. That time I did everything I knew to do and talked to factory service techs repeatedly and finally installed new furnace. As far as your question about insulation,. As long as it is fire proof I can't see where it would hurt anything. Sorry I'm not more help. Good luck and thanks.
An indoor blower running when it is not supposed to usually indicates an overheat condition. I would guess that it has been cycling on and off for some time and finally caused the high limit to stick and not auto reset. if you tap it sometimes they reset. the real problem is that it has been overheating from lack of airflow, over sized unit, not enough return air, too many closed registers, dirty filter, dirty squirrel cage blower and or air conditioner a-coil. If you get it started again sit and watch the unit run the flames should come on and stay on for the entire heating cycle, not going on and off.
I wish I could help you more but it is difficult without seeing the problem myself. Good luck! this should get you started!
It is possible that you did not set the new blower on the proper speed. Black wire is high. Blue is medium. Red is low. If the fan is operating to slow it can run to hot and trip the high limit control. Make sure the filters are clean. When the old motor went bad, the problem might not have been discovered rite away your high limit control might need to be changed.
Also anytime you work on a furnace you can kick up some dust. Always clean the flame sensor.
ok...where to start.lol ....the thermostat is just a switch.It will tell the unit to run or not run.if you measure the temp with the heatpump running,the air is warmer than 68 but it feels cool to you because your body is 98.6.The unit will run more often and for longer periods when the temperature drops outside for a few reasons.First,your house has more of a load to heat,meaning you have more heat loss because of the difference in temperatures outside and inside.Second,your heat pump pulls heat from the outside air.The colder the air outside,the less btu's for it to pull.If you have anymore questions firstname.lastname@example.org Hope this helps,Dave