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Heil Furnace Error Codes

Error Codes What this means How to fix it
LED flashing like a heartbeat Control has 24 VAC power n/a
Two LED flashes Unit’s pressure switch didn’t open Check for an obstruction in the pressure tubing
Three LED flashes Unit’s pressure switch didn’t close or reopened Check for: excessive wind; if it’s the proper vent size; defective inducer motor; defective pressure switch; inadequate combustion air supply; disconnected or obstructed pressure tubing; or restricted vent
Four LED flashes Limit circuit fault: either a limit or flame rollout is open Check for: restricted vent; loose blower wheel; excessive wind; dirty air filter; or defective blower
Five LED flashes An abnormal flame proving signal, the flame is likely proved while the gas valve is de-energized Check for a leaky gas valve or a gas valve that is stuck open
Six LED flashes Failure to ignite or the flame sensor was lost while running Check for: an ungrounded flame sensor; defective hot surface ignitor; control ground continuity; inadequate flame carryover; or rough ignition
Seven LED flashes Limit circuit lockout A lockout will occur if the limit or flame rollout is open for longer than 3 minutes. Control will auto-reset after 3 hours.
Eight LED flashes Gas heating lockout, control won’t auto-reset Check for a miswired gas valve or a defective control valve
Ten LED flashes Polarity is reversed Review instructions to correct polarity
1 + 2 Blower is on after power up Occurs if the unit is powered up during a call for heat or opens while the blower is on delay
6 + 1 Ignition lockout Control will auto-reset after 3 hours
LED is off Secondary voltage fuse is open Check whether the door switch isn’t closed or for a short circuit
LED is on Control circuitry lockout Will auto-reset after 1 hour
LED is solid Gas valve relay is stuck while open, flame sense circuit failure, or software-check error Reset power to clear the lockout and then replace control if status code repeats itself
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