Nordyne G5 - blower won't come on

[nuclearmateo]

I've been troubleshooting this furnace myself for several years, never had a problem that a new ignitor or flame sensor wouldn't fix, until today.

This morning, had an error code on the trouble light - one flash every second. Shutting down power to the furnace for several minutes cleared that. Upon startup, everything functions as normal until the main blower is supposed to come on - and it doesn't.

Sounds like the relay to kick on the blower fires at the appropriate time - how do I troubleshoot this?

[nuclearmateo]

A bit more -

having the T-stat set to fan on, with the stat not calling for heat, the fan comes on.

any time the t-stat calls for heat, the fan seems to not call on, resulting in a shutdown of the gas valve at the appropriate time, and flashing the fault light.

hopefully this will help those more experienced than I

[nuclearmateo]

Unit is a G5RA -indicates limit switch open.
Checked fan limit switch-good. Next more - one of 3 Flame roll-out sensors?

[nuclearmateo]

Getting continuity across all limit switches. Circuit board? Everything else seems to work properly!

Please Help!

[dependable]

Sounds like your control board has gone bad.

[nuclearmateo]

Yup. Sure did. Replaced it, and all good.

Thanks.

[aircooledtx]

**"nuclearmateo"-*'ve been troubleshooting this furnace myself for several years, never had a problem that a new ignitor or flame sensor wouldn't fix, until today.

This morning, had an error code on the trouble light - one flash every second. Shutting down power to the furnace for several minutes cleared that. Upon startup, everything functions as normal until the main blower is supposed to come on - and it doesn't.

Sounds like the relay to kick on the blower fires at the appropriate time - how do I troubleshoot this?*/-*
#1 gas furnace * 120v blower mtr


#2 speed red/low
#3 ground