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airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8245
Experience:  Furnace, A/C and heat pump specialist.
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I have a Thermal Zone GU080M16B. The problem with it is that

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I have a Thermal Zone GU080M16B. The problem with it is that the ignitor will not start up. What the heater would do when I turn it on is start up, skip starting up the ignitor and opening the gas and goes straight to blowing the air throughout the house.


Hi my name isXXXXX will do my best to solve your problem. Reply to this post and i will reply back with help before rating, Thanks Garyc




hi, i have a problem with my heater and the heater won't come on and the gas valve won't open. i measured the voltage to the ignitor and im not getting any voltage


i even bypass to the air pressure switches still didn't get any voltage

Hello. My name is XXXXX XXXXX I'll do my best to help. Troubleshooting often requires meters and test equipment. Let's get started and see what we can do.
1. Do you have a volt meter for troubleshooting?
2.Does the induced draft vent motor come on? We will go from here.
Customer: replied 3 years ago.

Yes, to both 1 and 2.

Ok lets do this, Turn the thermostat to call for heat,allow the inducer motor to come on and then pressure switch should click(close) and send message to the ignitor.
Id your ignitor a spark or glow bar?
Customer: replied 3 years ago.

The ignitor just doesn't turn on at all.

Is your ignitor a spark or glow bar?
Customer: replied 3 years ago.

It's a hot surface ignitor.

Ok, Great. Now unplug the molex connector on the ignitor,Place leads of your meter into the molex plug and let's see if we are getting 120v when pressure switch closes.

Plug coming to ignitor of course as ignitor is unplugged


Customer: replied 3 years ago.

The plug to the ignitor is not giving any voltage.

Ok, Disconnect the hose from the inducer motor ,leave attached to pressure switch.Allow inducer to start then suck on hose and make sure pressure switch closes and see if ignitor will start to glow.
Customer: replied 3 years ago.

Nope, it won't glow. After a minute of sucking on the hose, it still won't turn on.

Have you checked all limits to make sure none are open. You should have at least two above burners that will reset by pushing button in center. We can also jump any fixed limit for troubleshooting or ohm each one out
Customer: replied 3 years ago.

None of them are open.

I don't have a manual in front of me for your unit, but are you getting a flash code and if so, there should be a troubleshooting chart on front of furnace indicating what the code stands for such as 2 flashes (open limit).

Are we getting such a code and if so what is the code say?


Customer: replied 3 years ago.

Problem solved: it turned out that the pressure switch was stuck so it wouldn't close unless I sucked on it hard. It got unstuck and I tested it a few times and it works again and again. Thanks for the help though.

Thanks for allowing me to work with you on this.
airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8245
Experience: Furnace, A/C and heat pump specialist.
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