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McQuay Furnace Error Codes
If you're looking for help fixing your McQuay Furnace, look no further! Our comprehensive McQuay Furnace error code guide will explain common issues, provide tips, and show you how to read your model's error codes.
CODE: SLOW GREEN FLASH
RESULT: Normal operation
CODE: SLOW AMBER FLASH
RESULT: Normal operation with call for heat
CODE: RAPID RED FLASH
RESULT: Twinning error, incorrect 24V phasing.
FIX: Check twinning wiring. Flame sense current is below 1.5 microamps
CODE: RAPID AMBER FLASH
RESULT: Check and clean flame sensor. Check for proper gas flow. Verify that current is greater than 1.5 microamps at flame current test pad.
CODE: 4 AMBER FLASHES
RESULT: The control is receiving a "Y" signal from the thermostat without a "G" signal, indicating improper thermostat wiring.
CODE: 1 RED FLASH
RESULT: This indicates that flame was sensed when there was not a call for heat.
FIX: The control will turn on both the inducer motor and supply air blower. A gas valve that leaks or is slow closing would typically cause this fault.
CODE: 2 RED FLASHES
RESULT: This indicates that the normally open pressure switch contacts are stuck in the closed position.
FIX: The control confirms these contacts are open at the beginning of each heat cycle. This would indicate a faulty pressure switch or miswiring. This indicates the normally open pressure switch contact did not close after the inducer was energized.
CODE: 3 RED FLASHES
RESULT: This could be caused by a number of problems: faulty inducer, blocked vent pipe broken pressure switch hose or faulty pressure switch.
CODE: 4 RED FLASHES
RESULT: This indicates that the main limit switch has opened its normally closed contacts.
FIX: The control will operate the supply air blower and inducer. This condition may be caused by: dirty filter, improperly sized duct system, incorrect blower speed setting, incorrect firing rate or faulty blower motor. Also, this fault code could be caused by a blown fuse located on the control board.
CODE: 5 RED FLASHES
RESULT: This fault is indicated if the normally closed contacts in the rollout switch opens.
FIX: The rollout control is manually reset. If it has opened, check for proper combustion air, proper inducer operation, and primary heat exchanger failure or burner problem. Be sure to reset the switch and cycle power (24 VAC) to the control after correcting the failure condition. Also, this fault code could be caused by a blown fuse located on the control board.
CODE: 6 RED FLASHES
RESULT: This indicates that after the unit was operating, the pressure switch opened 4 times during the call for heat.
FIX: If the main blower is in a "Delay on" mode, it will complete it, and any subsequent delay off period. The furnace will lock out for one hour and then restart.
CODE: 7 RED FLASHES
RESULT: This fault code indicates that the flame could not be established. This no-light condition occurred 3 times (2 retries) during the call for heat before locking out.
FIX: Low gas pressure, faulty gas valve, dirty or faulty flame sensor, faulty hot surface ignitor or burner problem may cause this. The furnace will lock out for one hour and then restart.
CODE: 8 RED FLASHES
RESULT: This fault is indicated if the flame is lost 5 times (4 recycles) during the heating cycle.
FIX: This could be caused by low gas pressure, dirty or faulty flame sensor or faulty gas valve. The furnace will lock out for one hour and then restart.
CODE: 9 RED FLASHES
RESULT: Indicates reversed line voltage polarity or grounding problem.
FIX: Both heating and cooling operations will be affected. check polarity at furnace and branch. Check furnace grounding. Check that flame probe is not shorted to chassis.
CODE: 10 RED FLASHES
RESULT: Flame sensed with no call for heat.
FIX: Check gas valve and gas valve wiring This indicates that a primary or auxiliary limit switch has opened its normally-closed contacts and has remained open for more than five minutes.
CODE: 11 RED FLASHES
RESULT: This condition is usually caused by a failed blower motor or blower wheel.
FIX: Cycle power (24 VAC) to the control to reset the hard lockout condition after correcting the failure condition.
CODE: 12 RED FLASHES
RESULT: This code indicates an open igniter circuit.
FIX: This could be a disconnected or loose wire or a cracked or broken igniter.
CODE: STEADY ON RED
RESULT: Control failure.
FIX: Replace control board.
CODE: 60-MINUTE AUTOMATIC RESET FROM LOCKOUT
RESULT: This control includes a "watchdog" type circuit that will reset from a lockout condition after 60 minutes. Operational faults 6, 7, 8 will be reset. This provides protection to an unoccupied structure if a temporary condition exists causing a furnace malfunction. An example would be a low incoming gas supply pressure preventing unit operation When the gas pressure is restored, at some point the "watchdog" would restart the unit and provide heat for the house.
CODE: IGNITION CONTROL FLAME SENSE LEVELS
RESULT: Normal flame sense current is approximately 3.7 microamps DC Low flame signal warning starts at 1.5 microamps. Low flame signal control lockout point is 0.1 microamps DC.
Related Price Pages:
McQuay Furnace fault codes
McQuay Furnace diagnostic codes
McQuay Furnace error symbols
McQuay Furnace common faults
I have had a Daikin furnace for four years now. I’ve always taken care of the furnace by having it checked and maintained annually. I also replace the filters after every eight weeks. The furnace has never failed and is always reliable even at the worst weather. My current technician tells me that the installers did a good job. The noise level is barely noticeable. I would recommend the Daikins Furnace to everyone.
My husband and I moved into our new home 2 years ago, but as soon as we settled, the furnace broke. We called a technician who advised that we should purchase a new furnace since the old one would continue giving us problems. He suggested that we go for Daikin and it has been a perfect choice. Sometimes, the warmth in the house is the only indication that it’s on. It keeps our home cozy and warm in just a short time even in the cold Wisconsin winters. We have not had any problems with the Daikin furnace so far. I would gladly buy it over and over again.
I recently purchased the Daikin Furnace and fell in love with it. It has cost me nothing more than the eighty dollars I pay for the annual checkup. It has cut my gas bills by over 50%. I don’t even turn off the furnace during winter. I know that the furnace is great and I guess that the problems people are experiencing are due to poor maintenance. I would recommend Daikin to everyone out there.
The Daikin furnace that I replaced had served our family efficiently for twenty five years until it broke down three years ago. I immediately replaced it with a newer model of Daikin. As always, it has low maintenance needs; all that is required is for me to change the filters at least three times a year. I have never had to repair the Daikin, but it still runs smoothly. If I were to make a furnace purchase again, I would still purchase this unit.
McQuay International, also known as Daikin Applied in the United States, offers air conditioning, heating, ventilating and refrigeration units. McQuay International is headquartered in Hong Kong, with U.S. headquarters in Minneapolis, MN. The company is owned by Daikin, a fortune 1000 company. Daikin reported revenue of approximately $18.4 billion USD in 2017.