Blower motor in air handler issue

[48RON54]

Let's start from the beginning.... The summer before last, the blower motor in my air handler failed so I had no AC. I replaced the blower motor and voila all was good and I had AC again. Last winter came around, and the blower motor wouldn't come on when I tried to heat the home. I tested the t-stat per youtube instructions and determined it was a failed t-stat. Replaced t-stat with new one in May, tested heater and AC and all was good. Last night I turn the heat on for the first time this year and the furnace kicks on but kicks off a few minutes later and the fan/blower motor never comes on. I can put the fan in the on position as opposed to auto and then put the t-stat to heat and that will work, but not in auto. But....me not being so familiar with heating and air, I'm wondering if the furnace is stopping the fan for a safety reason of some sort so I'm rather leery of forcing it to heat the home like that at all. What do you guys think? T-stat failed again? Is there something else I should be looking at here?

 

[zmaxmotorsports]

Let's start from the beginning.... The summer before last, the blower motor in my air handler failed so I had no AC. I replaced the blower motor and voila all was good and I had AC again. Last winter came around, and the blower motor wouldn't come on when I tried to heat the home. I tested the t-stat per youtube instructions and determined it was a failed t-stat. Replaced t-stat with new one in May, tested heater and AC and all was good. Last night I turn the heat on for the first time this year and the furnace kicks on but kicks off a few minutes later and the fan/blower motor never comes on. I can put the fan in the on position as opposed to auto and then put the t-stat to heat and that will work, but not in auto. But....me not being so familiar with heating and air, I'm wondering if the furnace is stopping the fan for a safety reason of some sort so I'm rather leery of forcing it to heat the home like that at all. What do you guys think? T-stat failed again? Is there something else I should be looking at here?

Your blower should have multiple speeds,try switching your red wire from blower with the blue wire and see If it comes on.
That will at least eliminate the low speed side of motor.

 

[48RON54]

Your blower should have multiple speeds,try switching your red wire from blower with the blue wire and see If it comes on.
That will at least eliminate the low speed side of motor.

Thanks....that had actually been on my mind....the supposed OEM motor came with more speeds than the original one and the blue one is the one left unconnected. I will try that.

 

[TommyK]

The blower bearings may be seized in which case when the unit reaches the high limit it will turn off because no air is moving across the heat exchanger causing it to short cycle.

With the power off try turning the blower by hand. If it doesn't spin freely you may have found the problem.

 

[James-W]

The blower bearings may be seized in which case when the unit reaches the high limit it will turn off because no air is moving across the heat exchanger causing it to short cycle.

With the power off try turning the blower by hand. If it doesn't spin freely you may have found the problem.

I agree, spinning the motor by hand will tell you right away if the bearings are bad.

 

[AA7483]

Its likely a bad relay on the circuit board.

 

[yeldogt]

If the heater actually starts and runs for a while -- producing heat. The heater is working ... it would click off on safety in under a minute if the heat cycle was the problem.

Sounds to me as if the control for the fan is not working and the heater finally gets too hot and turns off as no air is going over the exchanger.

I would be looking at the relay or control board ... if you move the fan to manual (on the Tstat) the fan should start ... you should hear a click of the relay.

 

[Done That]

I agree take a close look at the control board in the unit, looking for a relay issue. A pic of the board and its wiring may also help us to help you. Is this a gas furnace, or an electric air handler? You used both terms...
Some furnace boards have only heat and cool relays, while others add a dedicated fan speed relay.
A lot of possible ways to mix up the wires or setup with the tstat.

 

[bobbyjean]

did you replace the run capacitor?

 

[dfiler2]

You said the blower fan works when you turn it to the "on" position, correct? If that's the case I would take a close look at the thermostat wires and make sure a wire hasn't come loose, may not have gotten it tightened when you changed it last spring.

 

[bobbyjean]

the fan may cycle thru a temperature control (heating)if unit is older...should look like a small disc with two or three wire's running to it....
you can try to make a jumper wire to test at both thermostat and unit r to g should cycle cooling fan (high) speed r to w should cycle lower speed fan .
is it a furnace ? gas/electric

 

[LS6 Tommy]

Guys, if the heat and fan runs with the t-stat set to "Fan On", it's not the t-stat or the motor. It's most likely the fan/limit switch or the fan relay. Does it trip the rollout or hi limit manual resets?

Tommy

 

[zmaxmotorsports]

Guys, if the heat and fan runs with the t-stat set to "Fan On", it's not the t-stat or the motor. It's most likely the fan/limit switch or the fan relay. Does it trip the rollout or hi limit manual resets?

Tommy

The fan on setting and the call for heat use 2 different speeds on blower,that's why I said to switch the red and blue to make sure low speed on blower was actually working to eliminate it .
Takes 5 mins to eliminate it as a possibility,not a big deal.

 

[brewchief]

Is the thermostat configured properly? If you have electric heat strips many times you have to set the thermostat to electric heat, when set this way it will close the G terminal as well as the W with a call for heat.

Sent from my XT1254 using Tapatalk

 

[zmaxmotorsports]

So what ever became of the original poster,did he get it fixed?
The boys in Vegas wanna know.

 

[bobbyjean]

laying odds that unit met a hammer-ba dum bum

 

[zmaxmotorsports]