blower motor won't shut off - http://www.hvacmechanic.com/ Forums
Original message
| mohguy
 |  "blower motor won't shut off"
, posted Sun 20 Jul 15:42  
I have an old carrier heat/cool roof mount unit. (20 yrs old) When I run the air all is fine. When I move the thermostat up to shut air off the compressor stops running but the blower motor will not shut off. I have to shut off at the breaker. I am trying to figure out what part to replace and where it is located. Help. Thank you
david
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Replies:
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| Freon
| "Re(1):blower motor won't shut off" , posted Mon 21 Jul 15:08
Be sure the thermostat FAN setting is AUTO, not ON. If already set to Auto, measure the AC voltage at the air handler between the G and C terminals. If you get 24 volts, then there is something wrong with either the thermostat or thermostat wires. Turn off power. Remove the wire at the G terminal at the 'stat. Turn power on. If fan is stopped, the 'stat may be the problem. If the fn is running AND you still get 24 volts AC between G and C at the air handler, the wiring is a possible cause.
Otherwise you may have a frozen relay. Turn off the power and trace the motor wires back. They should connect to a relay. The relay is either welded shut or the 24 volts energizing the realy is not shutting off
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