Redundant high-limit relay stuck closed: the service facts call this an internal control-board error. The relay is closed when it should not be.
Likely causes
- Redundant HLO relay closed when it should not be
Safe checks for E7.2
- Write down E7.2. E7.1 is 24 volts present on the 1st stage gas valve when it should be off. E7.2 is this relay fault
- Technicianthe troubleshooting step for fault 7.2 is to replace the integrated furnace control
Capacitors can hold a charge after the power is off. Safety terms.
When to call a pro
Call a licensed HVAC technician. E7.2 stays on the control board. There is no filter step on this row.
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Parts & tools for this fix
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Furnace control board and low-voltage fuse: guide
In this code: Parts list for this code: Integrated furnace control
This one is for a technician to test or replace, so we only explain it and do not link to buy it.
Multimeter for appliance and HVAC diagnosis: guide
In this code: Write down E7.2. E7.1 is 24 volts present on the 1st stage gas valve when it should be off. E7.2 is this relay fault
This one is for a technician to test or replace, so we only explain it and do not link to buy it.