4+1 Blower motor fault

What the control is telling you

Blower did not reach 250 RPM or failed to communicate: within 30 seconds of start, or within 10 seconds during steady running.

Applies to: ICP F9MAE / G9MAE modulating variable-speed condensing gas furnaces (060, 080, 100, 120 kBtu/h)

Likely causes

• Rubbing or loose blower wheel
• Open wire / bad terminal between control and motor (BLACK/WHITE, RED/GREEN, YELLOW, BLUE)
• Failed blower control module
• Failed furnace control

Test and repair steps

1. Warning: Turn power off before working on the blower.
2. Remove R from the control, unplug PL13 and PL14 at the motor; check the wheel spins freely - if not, fix the wheel/motor.
3. Power on check 115 VAC at PL14-5 to PL14-4; if missing, find the open BLACK or WHITE lead (disconnect power choke if fitted and check continuity).
4. Check 12 VDC at PL13-1 RED(+) to PL13-4 GREEN(-); if missing check PL3-1 to PL3-2 at the control - missing there = replace control, present there = open RED/GREEN wire.
5. Check 5 VDC at PL13-2 YELLOW(+) to PL13-4 GREEN(-); if missing, check PL3-3 to PL3-2 at control - missing = replace control, present = open YELLOW wire. Reading must be stable within 0.02 VDC.
6. With PL13/PL14 unplugged, check PL13-3 BLUE(+) to PL13-4: near 0 VDC with brief pulses several times a second; if no pulses, check PL3-4 to PL3-2 at control (no pulses = replace control, pulses = open BLUE wire).
7. Reconnect motor; if PL3-3 YELLOW voltage fluctuates more than before, replace the blower control module (check whether the whole motor needs replacing); otherwise replace the furnace control.