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Kenton Guidry
Kenton Guidry, HVAC Technician
Category: HVAC
Satisfied Customers: 966
Experience:  12 years install/service experience.
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The heat on my A/C wont come on. I can hear click o

Resolved Question:

The "heat" on my A/C won't come on. I can hear click on thermostat, but NO fan or heat from the unit kicks on. Circuits haven't tripped. The "cool" on the A/C works. Just the "heat" won't come on?? Can you help?
Submitted: 7 years ago.
Category: HVAC
Expert:  Kenton Guidry replied 7 years ago.
Please turn your furnace off. Wait one minute. Then turn it back on. After that watch the furnace start up. You will need to remove one of the panels to observe the following.

Gas furnaces have a start sequence they must go through.

The first step is that the furnace will get the signal from the thermostat to turn on.

Then the induced draft fan will come on. Not all systems have this fan.

After that, if you have an induced draft fan, the pressure switch will close because of the induced draft fan running.

Once that happens your ignition will attempt to ignite the flame.

If you have a spark ignition the ignitor will spark. If you have a hot surface ignitor, the ignitor will glow very bright from being so hot.

This is when the gas valve should open.

The gas will not ignite.

Then the flame sensor will sense the flame.

Once the flame is sensed, the heat exchanger will warm up.

After the heat exchanger warms up the indoor blower motor will start.

Let me know how your system runs compared to the above description.
Kenton Guidry and 2 other HVAC Specialists are ready to help you
Customer: replied 7 years ago.
I don't know that I can remove the "panel" that you suggested me to do as my A/C unit is located on my roof??...
Expert:  Kenton Guidry replied 7 years ago.
Then you must call out a service company.
Customer: replied 7 years ago.
Thank you for your help. I did call out a service tech. And, when he arrived I turned on the heat at the thermostat and it "worked"!! Go figure. He had a few explanations why it would work and then all of a sudden not work. And, things to try before I call next time (should it happen again :-(( ...BotXXXXX XXXXXne... I paid you and a service tech for an H/A unit that started to work all on it's own. ??? But, what's a person to do when you don't know how to "fix" something??? Call a Service Tech. Thanks anyway.
Expert:  Kenton Guidry replied 7 years ago.
You can try to trouble shoot it but if you cannot get to the system then it was best to call someone out.
Customer: replied 7 years ago.
Thanks for the help. It's all fixed. I called a Tech. The system began working all on its own. Go figure. But, thanks anyway. We're all done. Bye.
Expert:  Kenton Guidry replied 7 years ago.

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