Thermo Products MHA1-75N, MDA1-50N, MHA1-100N, MHA1-50N, MHA1-125N, MDA1-75N, MDA1-125N, MDA1-100N

All installations and services must be performed by qualified service personnel.

Yes Yes

Is there 120 VAC across draft inducer power terminals "IND"

&"IND N" at the ignition control module?

No

Yes

After pre-purge,does the

hot surface ignitor energize

and glow?

Yes

After hot surface ignitor warm-up, does gas valve open?

Yes

Check wiring to draft inducer.

If okay, replace inducer assembly.

No
	Is there voltage present at the	No
	hot surface ignitor terminals
	"IGN" & "IGN N" at the ignition
	control module?

Yes

Check wiring to hot surface ignitor. If okay, replace hot surface ignitor assembly.

No	Check across "MV" terminals
	on ignition control module for 24
	VAC during the 4 second flame
	proving period after ignitor
	warm-up. Is there 24 VAC?

Yes

Check the ignition control module diagnostic LED lamp. Reset the module by interrupting power to system for more than one second. If LED stays on continuously, replace ignition control module.

No

Check wiring to gas valve. If okay, Replace gas valve.

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