Inducer motor fault on a Bryant 987MA modulating furnace. The inducer has not started within 20 seconds after a call for heat, the inducer RPM is outside its valid range, or the RPM signal was lost for 5 seconds during operation.
Bryant 42 is an inducer motor fault on the 987MA Series A modulating chart. The inducer did not start within 20 seconds after a call for heat, the RPM is outside its valid range, or the RPM signal was lost for 5 seconds while running. The chart lists vent sizing, a restricted vent, and a failed inducer. The 80% two-stage chart has no code 42. Code 41 on that chart is the blower, not the inducer.
Likely causes
- Inducer did not start within 20 seconds of a call for heat
- Inducer RPM outside its valid range, or the RPM signal lost for 5 seconds
- Vent sizing is wrong, or the vent is restricted
- Failed inducer motor
Safe checks for 42
- Look at the outdoor intake and exhaust terminations for a blockage. Leave the pipes connected
- Techniciancheck vent sizing, a restricted vent, and the inducer motor. This code is not blower fault 41
Capacitors can hold a charge after the power is off. Safety terms.
When to call a pro
Call a licensed HVAC technician if the terminations are clear and 42 remains. Inducer replacement is not a homeowner job.
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Furnace inducer (draft) motor: guide
In this code: Inducer did not start within 20 seconds of a call for heat
This one is for a technician to test or replace, so we only explain it and do not link to buy it.
Furnace blower (circulator) motor: guide
Technician step in this code: check vent sizing, a restricted vent, and the inducer motor. This code is not blower fault 41
This one is for a technician to test or replace, so we only explain it and do not link to buy it.