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-   -   Help with a furnace blower that doesn't turn on correctly. (http://www.diychatroom.com/f17/help-furnace-blower-doesnt-turn-correctly-166752/)

howie50 12-18-2012 01:52 AM

Help with a furnace blower that doesn't turn on correctly.
 
Hello,
Maybe somebody can help me again.
I have a gas furnace that has a problem with the blower motor turning on correctly.
The blower will turn on when switched to "on".
The gas furnace fires up ok, but the blower does not turn on after the burners ignite.
Of course, the overheat sensor trips and the gas stops.
If, after the burners ignite, I switch the fan manually to "on" the heating system works, kind of....

The same system has an air conditioner, and everything works ok when in that function.

I suspect that something is wired incorrectly..
Is a general schematic or block diagram available?
Any thoughts on what the problem could be?

It's an old Amana with a White-Rodgers control module.
thanks

beenthere 12-18-2012 05:13 AM

Control, boards heat tap relay may be bad, or the motor's heat speed winding may be bad.

Use a multimeter to test for voltage from the heating fan terminal.

hvac dude 12-19-2012 09:51 PM

re fan motor
 
hi there ,, make and model will help ,, as unit may not have a control board may be old school ,,, there shud be a fan switch of some kind to tell when to start motor once heat exchanger has warmed up ,,, but make and model will deff help .. keep in touch

oncall 12-21-2012 08:18 AM

A few things can cause this.
That's why some easy questions need answered.
Was the thermostat changed recently?
Do you have voltage at the motor, when the furnace is heating up,(remember your furnace fan will come on when a certain temp. is reach within the furnace, or it might have a timimg for when the motor will come on, depending on the type of controls


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