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No LED on 350MAV Control Board

4965 Views 32 Replies 7 Participants Last post by  samworkss
I have a 350MAV036060F Bryant Plus 90 furnace whose blower had stopped working and control board LED was flashing 31.
I could cycle the emergency switch to reset but after a couple mins it would shutdown and flash 31 again. Having checked the meaning of code, I performed the following:
1. Checked the vents and intake PVC lines to ensure no blockage.
2. Checked the lines on the pressure switch.
3. Checked the condensate trap.
4. Checked the filter condition.

Not having solved the problem, I saw somewhere online I can test if the blower motor is good by jumping L1 and the blue 'heat' line. When I did that I heard a soft humming sound and the yellow LED went off. Fearing that I had messed up the control board (HK42FZ014), I bought one online and replaced it properly only to find that the LED is still off. I checked the 3A fuse on both old and new boards and it appears good. I used my multimeter and I am getting 120V coming thru the door switch when I tape it shut. I do not get any voltage going to the capacitor and thus no 24V coming out of it. HELP PLEASE!!
1 - 6 of 33 Posts
The capacitor doesn't output 24 volts.

Hope you mean the transformer. If your not getting 120 volt to the transformer, its probably wired wrong.

How did you measure your 120 volts through the switch. Did you measure to ground, or to neutral.
Are you sure you have the transformers line voltage wires on the right terminals of the board so it gets 120 volts? Did you check for 120 volts on those terminals.
Ohm out the limits. Your filter may have been too dirty for a while before you changed it, and the limit may now be stuck open. Also, could be that the capacitor for the blower is bad, and that is what caused the limit to trip, and why the blower doesn't run.
Limit switch would be in the burner compartment.
Should be on the right side as I recall. Its not fastened to the burner compartment itself. but to the jacket. Your furnace has a high limit.
You have a high limit somewhere.

If you have an open roll out. You may have more serious problems.
1 - 6 of 33 Posts
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