Bryant
31 / 42
LockoutPressure / inducer band
Modulating inducer did not hit the band for the commanded rate.
Walk 31 / 42 in Diagnose
Sign in for the next measurement
First check
1 Prove inducer and the live code
Do not pull power — that clears the Bryant 987M active code. Write 31 / 42. Is the inducer spinning on this call? Silent inducer is not a pressure switch. Vent, trap, inducer, transducer/hose — do not ohm a ‘low’ and ‘high’ switch that are not there.
Expect: 120 VAC at the inducer on a heat call. Wheel turning.
If fail: 120 VAC missing → IFC / door switch / incoming power. Voltage + dead motor → inducer.
If pass: Inducer running + this code → trap, hose, switch, vent (step 2).
The rest of the walkthrough is Diagnose.
On the plates
- Vent, trap, inducer, transducer/hose — do not ohm a ‘low’ and ‘high’ switch that are not there.
- 42 = inducer RPM out of the commanded band.
Plates that use 31 / 42
Same number, other makers
31 / 42 on Bryant is not the same code on these plates.