Intertherm gas furnace won't start

[jmittl]

model MMHB-070ABHR-06 - HSI LED continuously blinks twice - have replaced HSI and inducer motor 3-07, still get LED error.

This has been going on for a few years now, intermittently until this year, when I can hardly get the inducer motor to fire up at all.

Have tried cycling power both at the breaker box and thermostat - inducer motor will start maybe once every 20 tries, if even then.

Had an HVAC/electrician type look at it last March, he couldn't figure out why the unit failed to fire up. Voltages at transformer are correct. Just by chance, it began to work correctly at that time, but no longer does.

Tried recently replacing thermostat, same result.

Relay? Limit switch(es)?

Urgent - I live high up in the Rockies, where summer is definitely over. Need to be able to heat my home above 53 degrees.

Any advice would be greatly appreciated!!

Jim

[Robert]

Hi Jim,

Make sure the air pipe to the combustion motor is clear. If so, the motor builds up to a certain speed and the centrifugal switch inside motor housing closes, sending signal on for heat cycle.


Keep an eye on the HSI Control Module and test there for voltage when needed.

Test at ignitor. Make sure voltage is applied at all times when it should be.


Check the burner and burner orifice for blockages and be sure the orifice is correct one.


Check roof-jack/flue for seperations between pipes and damage. Be sure it terminates above roof peak and has a weather cap on it.


It could be a bad HSI Control Module.


Thanks,
Robert