Blower motor shuts off immediately

Problems related to residential installations.

Blower motor shuts off immediately

Postby madhu621 » Wed Aug 31, 2016 11:04 pm

Hi - I have a Nordyne HVAC GC RC 80 model. I have a problem with the air flow. When I put the fan to ON position in my thermostat, the blower motor turns on and shuts off within seconds .I hear a click sound, motor comes on and hear a click and motor stops. Sometimes when I turn the fan on, I don't hear a click at all.

I removed the blower assembly, tested the motor and it runs fine. When I connected power to blue and white cables, the motor runs fine. I also replaced the capacitor. I am not sure what else I need to look at.

Any ideas? Please help. Thanks.
madhu621
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- Blower motor shuts off immediately

Postby Freon » Thu Sep 01, 2016 10:28 am

Is the click sound you hear at the thermostat? Here's a test. Turnoff the power to the air handler. Remove the front of the thermostat exposing the wire connections. Get a short wire to use as a jumper. With the power back on, you want to CAREFULLY jumper (connect) the R terminal to the G terminal. Does the fan stay on?

The voltage at the thermostat is 24 volts so the only danger is touching the R terminal (+24 volts) to anoher terminal except the G. Any questions please ask, if you are uncertain.
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- Blower motor shuts off immediately

Postby madhu621 » Thu Sep 01, 2016 10:30 am

I can test that and let you know.

The click sound does not come from the thermostat, it was coming from somewhere near the control board.
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- Blower motor shuts off immediately

Postby madhu621 » Thu Sep 01, 2016 6:18 pm

Hi Freon, Thanks for helping me. I tried what you suggested.

I shorted the R & G terminal as you said and here is what -

- I Mostly had success and 8 out of 10 attempts the blower was running. I have 2 LEDs on the circuit board (yellow and red). When the motor was running both of them are on.
- Couple of times it immediately stopped within 1-2 seconds. When this happens red LED turns off and becomes very feeble and it was flickering.
- The sound is coming from a relay or a contact from the control circuit board(one of the black boxes)

When I put the thermostat back on and turn the fan on, the success rate was much less (2 out of 10) but the symptoms are pretty much the same.
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- Blower motor shuts off immediately

Postby Freon » Sat Sep 03, 2016 1:24 pm

Good job testing. It seems the clicking you're hearing are the relays on the control board. The red LED dimming may indicate a voltage problem on the board either due to a bad component on the circuit board ot poor wiring to the control board. Turn off the power and check all wiring from the 120 volt house side to the air handler. Especially check all ground and neutral connections. Also examine the 24 volt transformer. It could be going bad also thereby not delivering the necessary amperage for the relays to function.

Also check the control board where you see little black boxes, usually relays. Do the solder joints seen in good condition? A cold solder joint can also give you intermittent operation.
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- Blower motor shuts off immediately

Postby madhu621 » Sun Sep 04, 2016 10:10 am

Hi Freon, Thanks again. How do I check the 24v transformer? Should I check the output in multimeter? I also found a control circuit board on Amazon and bought it hoping that would fix the problem.
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- Blower motor shuts off immediately

Postby Freon » Sun Sep 04, 2016 3:31 pm

Since you have a new control board, replace the old one. See how that goes.

Checking the transformer can be tricky. Here is what I would do. On the control board find where the transformer connects to the board. Usually it's at the R (+24) and C (common) terminals. Using your multimeter set to volts AC, check the voltage betweem R and C. It should be 24 volts. Now with the multimeter still measuring the voltage between R and C have someone call for the FAN. See if the voltage drops. It shouldn't.
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