Comfortmaker Furnace Troubleshooting

If you have never heard of Comfortmaker furnaces and at the same time you are somehow connected with this business, it’s going to be rather surprising. If you got one of them and see that something goes wrong, check if this troubleshooting guide can help. In most cases it really does the repair possible. Only if it doesn’t help, you can return it due to the guarantee period or call the service.

Comfortmaker G9MAE Furnace Troubleshooting

Problem	Solution
Burner does not light when thermostat calls for heat	1. Check for possible air in gas lines. Reset thermostat and cycle furnace several times to bleed system.
	2. Check gas supply pressure while in operation. Supply 11" W.C. pressure to the furnace. M^ke sure the valve knob is in the “on” position, the switch on the side of the junction box is on, and the circuit breaker is pushed in. Check manual reset switch located on the side of the blower housing.
	3. Check for voltage at the terminals of the control module. If “0" VDC, check thermostat wires, manual and high limits. Power should be present between all of these components and ground
Continuous sparking	1. Continuous sparking is caused by separations in the high tension lead wire or poor terminal connections. Repair or replace
Erratic blower and/or thermostat operation	1. Check the wiring to the furnace.
	2. Check for shorts and open circuits in wiring.
	3. Disconnect leads to the gas valve, if furnace runs properly with the leads removed. Replace the gas valve.
Repeated control module failures	1. Check to be sure that the igniter or the high tension lead is not sparking to the sensor or the lead wire.
	2. Check the voltage from the coach converter. If over 14% VDC output is present, adjust or replace the converter.
Blower is noisy	1. Check for debris in the wheel or damage or looseness. Remove debris, and tighten wheel properly. If damaged, replace.
	2. Check for excessive voltage, and correct.
	3. Check polarity. If reversed, the motor will whine and run backwards.
	4. The wheel may be hitting housing; adjust wheel position with alien wrench.
	5. Check for loose motor mounts and retighten.

Comfortmaker G9MXT Furnace Troubleshooting

Problem	Cause	Solution
Main burner will not shut down	Short in thermostat wire.	Replace thermostat wire.
	Thermostat mounted in cold location.	Relocate.
	Operative control with no voltage at valve.	Replace control.
Fan will not come on	No 12 volt power to motor.	Check 12 volt power to motor.
	Faulty 115° fan switch.	Replace fan switch.
	Seized or burned out motor.	Replace motor.
Fan will not shut off	Faulty 115° fan switch, will not open.	Replace fan switch.
	Obstructed ducting. Obstructed return air.	Check for obstruction and clean.
Furnace fails to operate with wall thermostat	Short in wire to wall thermostat.	Check by unhooking W.T. wires at control and use jumper wire.
	Control hooked to 12 volt power.	If furnace ignites, replace wire.
	Faulty wall thermostat.	Replace control.
		Check by crossing wires at W.T.
Blower noisy	Debris inside blower wheel.	Remove debris and clean wheel.
	Motor mounts loose.	Retighten.
	Blower wheel loose on shaft.	Adjust and tighten.
	Reversed motor polarity, motor running backwards.	Wire for correct polarity.
	Loose blower assembly.	Tighten screws between blower housing and fan support wall.
	Blower wheel out of balance.	Replace wheel.
Leaking valve	Overfilled gas bottle.	Replace valve. Check bottle. (Not covered by warranty.)
	Valve subjected to high pressure test.	Replace valve. (Not covered by warranty.)
Odors	Obstructed vent.	Check for obstruction.
	High pressure gas.	Check gas pressure setting.
Humming noise	Convertors on AC units.	This is normal.

Comfortmaker N8MXL Furnace Troubleshooting

Problem	Solution
EXCESSIVE COMBUSTION VENT OR FLUE BLOCKAGE	If pressure against induced draft blower outlet becomes excessive, the pressure switch will open and shut off the gas valve until acceptable combustion pressure is again available
LOSS OF FLAM	If loss of flame occurs during a heating cycle, or flame is not present at the sensor, the flame control module will close the gas valve. The flame control module will then recycle the ignition sequence, then if ignition is not achieved, it will shut off the gas valve and lock out the system.
POWER FAILURE	If there is a power failure during a heating cycle, the system will restart the ignition sequence automatically when power is restored, if the thermostat still calls for heat
GAS SUPPLY FAILURE	If loss of flame occurs during a heating cycle, the system integrated control module will recycle the ignition sequence, than if ignition is not achieved, the integrated control module will shut off the gas valve and lock out the system.
INDUCED DRAFT BLOWER FAILURE	If pressure is not sensed by the pressure switch, the contacts will remain open and not allow the gas valve to open, therefore the unit will not start. If failure occurs during a running cycle, the pressure switch contacts will open and the gas valve will close to shut the unit down.
CONDENSATE DRAIN BLOCKAGE	If the condensate drain is blocked, either by debris, im- proper draining, or by freezing condensate, the pressure switch will sense the accumulation of condensate in the furnace drain pan. The pressure switch contacts will open and remain open, not allowing unit operation. The unit will not operate until the condensate drain has been cleared, and the condensate flows freely
RESET AFTER LOCKOUT	When the integrated control module has shut the system down and gone into lockout, the system must be manually reset before the unit will restart. To reset, turn the system power off, then on, then off and then on again within 30 seconds. This may be done at the unit’s power source or at the thermostat. The system will not reset unless the procedure off-on-off-on is completed within 30 seconds.
RESET AFTER BURNER BOX LIMIT SHUTDOWN	If the furnace shuts down, one thing that can be checked is the burner box temperature limit switch. It is located on the bottom of the burner box. The vent and combustion air inlet terminations should be checked for blockage. If blockage exists, clear the problem and then the reset button may be depressed.