Blower for Heater won't start on Auto

Old 11-02-03, 08:12 PM
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Blower for Heater won't start on Auto

I have a Carrier system Model 58GC100-3A series 321. When the thermostat (Hunter Set n' Save I) is on "heat" and "auto", I can see the burners light, and the system acts like it is going to work normally, but the blower never comes on and the burners eventually shut back down. The blower does come on if I turn the thermostat to the "fan" position, and the blower comes on fine when the thermostat is set to "cool" and "auto". By the way, I live in Oklahoma.

Anyone have any ideas?
Old 11-03-03, 08:20 AM
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Sounds like your heating speed on the blower motor may be out...

The blower is a multi speed motor. So you'll have diffrent speed.. Low, med, and High.. (Some will have med-low, med-high).

Take a meter and see if you are getting power on the blower tap on the control board.

Another way of checking it removing the wire that is used for heating, and move another wire on it and see if it works.. If that works, the low speed winding is out.
Old 11-03-03, 07:26 PM
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In heat mode, the fan is activated by a temperature control or a time-delay control. If it is temperature control, it might be mounted near the limit control. That is what protects the furnace from getting red hot when the fan isn't working. If it is a time-delay control it could be mounted anywhere.

Try to locate the control responsible for the blower and give us a little more info and maybe we can help you out. You can trace the wires from the blower motor and work backward.
Old 11-04-03, 05:05 PM
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My friend had a similar problem last year and spent $500+ without having the motor replaced - just a thermostat switch.

My furnace started the problem this last weekend. After testing the thermostat to make sure the gas function was performing properly in the furnace, I then watched for the max heat switch located on the heater box above the burners to make sure it was turning off the gas when the temperature inside the box became to high. My furnace is a Trane, I have a rentall with a Rheem and it is configured the same. One wire to this switch runs to the blower. I turned off the breaker to the furnace and made sure the power was off. Then I disconnected the 3 wires going to this switch marking the position of each wire. I removed the switch from the furnace. Taking compressed air, I forced air into the insidecleaning out dirt and debris which had been lodged inside. My furnace is in the garage and collects dust and debris through out the year. In the case of Trane and Rheem,, this switch also acts to turn the fan on after the temperature in the box reaches a certain minimum. I reversed the procedures and turned on the circuit breaker. The furnace has worked fine since Sunday.
Old 11-15-10, 07:24 AM
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i have the same problem ..have replaced several parts ..still no luck..l=et me know
Old 11-15-10, 08:10 AM
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Please don't piggyback on an old thread --- it just causes confusion.

Start a new thread.

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