Mr. Heater MHT 45 Troubleshooting, Blower Does Not Come On, Igniter Does Not Spark, General

Section 7 TROUBLESHOOTING

General

This troubleshooting quide has been designed to assist you in locating and correcting minor problems that may occur with the MHT tube heater.

BLOWER DOES NOT COME ON

Possible Cause		Try This….
Power cord is not plugged in.		Plug power cord into a grounded three prong Outlet.
Thermostat setting is too low.		Increase thermostat temperature setting.
DSI module needs to be reset.		Unplug heater power cord from the electrical Outlet: wait for a
minimum of five seconds. Plug heater cord back	into outlet.
No power at electrical outlet.		Replace fuse or reset circuit breaker
Faulty blower motor		Replace blower motor.

IGNITER DOES NOT SPARK

Possible Cause	Try This…..
DSI module needs to be reset.	Unplug heater power cord from the electrical outlet: wait for a
	minimum of five seconds. Plug heater cord back into outlet.
Faulty igniter or ignition wire.	Unplug heater power cord from the electrical outlet; check igniter and
	ignition wire for damage. If damaged, replace igniter and/or ignition
	cable.
Air switch does not operate.	Check flue/air supply duct for obstructions; remove obstructions as
	required. Check for loose/leaky air hoses to the air switch; repair/
	replace/tighten hoses as required. Check for 24V across the secondary
	terminals 4 and 5 (red and yellow wires) of the transformer. IF NO:
	Check for 120V across the primary terminals 1 and 3 (black and white
	wires) of the transformer. If 120V is present, replace transformer. If 120V
	is not present, check wiring between power cord, blower motor and
	transformer. IF YES: Connect a jumper wire across air switch terminals;
	if jumper wire allows blower to operate, replace pressure switch (see
	replacement parts list for part number that applies to your unit rating).
Igniter spark gap incorrect.	Reset spark gap to 1/8’ (0.125”).

Mr. Heater Gas-Fired Low-Intensity Infrared Heater 20 Operating Instructions and Owner’s Manual