Gas and Oil Home Heating Furnaces - Old furnace
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rogerde53
11-04-09, 12:11 PM
Have an old COLEMAN PRESIDENTIAL 3 heat and air unit. The air system works fine. Blower kicks on automaticlly when it's suppose to. Switched the unit to heat and lit the pilot. The burners came on but the blower wouldn't. It finally got so hot it kicked my AUX Limit switch. Had to wait for unit to cool down to reset my limit switch. Went through heat lighting again and the same thing happened. HELP.
GRIMKNOTME
11-04-09, 12:49 PM
A wild guess heating fan relay , or a fan limit , there may be a box located above burners with a .. fan / auto option which would be to bring fan on , remove that cover and see if round disk is rotating as your burner first starts , it will take a minute or 3,4 if not turning tap with insulated end of screwdriver may move it if not replace it.
SeattlePioneer
11-04-09, 01:37 PM
I'd start by checking to see if the fan turns easily or if it's seized up from lack of lubrication or some other problem. Check to see if the fan motor turns freely and that the belt to drive the fan is intact and in good condition if it's not a fan driven directly from the fan motor.
The check to see if there is power to the fan switch, and check to see if the fan switch closes and energizes the contact going to the motor.
Check to see if you have power to the motor when the fan switch closes. Does the motor try to start? Will it start if you push the fan to help it start?
A bad capacitor can also be a problem, but I'd check thew above things first.
The check to see if there is power to the fan switch, and check to see if the fan switch closes and energizes the contact going to the motor.
Check to see if you have power to the motor when the fan switch closes. Does the motor try to start? Will it start if you push the fan to help it start?
A bad capacitor can also be a problem, but I'd check thew above things first.
rogerde53
11-04-09, 01:57 PM
Before the unit get's to hot I will switch the unit to on and the heater will work just fine. Switch it back to auto and the blow kicks off and the unit heats up and kicks the limit switch
GRIMKNOTME
11-04-09, 04:59 PM
Before the unit get's to hot I will switch the unit to on and the heater will work just fine. Switch it back to auto and the blow kicks off and the unit heats up and kicks the limit switch
On the fan limit as said before :confused:
On the fan limit as said before :confused:
ecman51`
11-04-09, 06:03 PM
Yes. It is bound to be......depending on what his furnace uses.......either a thermodisc fan control switch(that works on a heat sense principle) that is defective, and not "closing" - or - a fan-limit switch defective, - or - if he has a control board with 2 or 3 fan speed settings, it's possible that the faster fan On or A/C fan speeds works, while the AUTO setting does not, because the slower heat speed winding in the motor is shot. That can be found out by switching fan speed wires on the control board.