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I need to troubleshoot why my furnace won't fire up. I've…

Customer Question
I need to troubleshoot...

I need to troubleshoot why my furnace won't fire up. I've had trouble with the fan only coming on for 15-20 seconds at a time in the past, which was annoying but it still heated my garage ok. But now the burner and the fan won't come on. Any suggestions ?

Contractor's Assistant: Did you double-check the thermostat's settings? And what about the filters?

This is an overhead heater, no filters. I shorted out the thermostats terminals to over ride the mercury switch.

Contractor's Assistant: Do you plan on doing the work yourself?

Yes

Contractor's Assistant: Anything else we should know to help you best?

The pilot flame is on. I tried to wire brush the capillary tube I don't know if I was successful. I suspect That is why it won't ignite

Submitted: 4 months ago.Category: HVAC
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Answered in 25 minutes by:
3/22/2018
HVAC Technician: Phil, Mechanical Engineer replied 4 months ago
Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 9,718
Experience: Retired HVAC/ Electrical & Boiler contractor. Industrial
Verified

Hello. Stand next to the furnace, Listen to it when it tries to start, you should hear the following sequence

1. Small inducer fan should start

2. You should hear a faint click next, within 3 seconds of the inducer fan starting

3. In 20 to 40 seconds you should hear two more faint clicks

4. You should hear the burners fire

5. in 40 to 90 seconds the main blower should come on

6. it should keep running, if it stops after 2 to 10 seconds, its flame sensor rod is dirty

.

To go further than that test you will need a multi meter and some skill with it and I will need"

.

Take close up, exceedingly well focused photo's of the wiring diagram glued inside the furnace/air handler door, and the printed circuit board mounted on the blower, , that shows where the thermostat wires connect, and I will mark them up with trouble shooting instructions.

.

Use the 'add files' link next to your send button to get the photo(s) to me.

.

We can go from there with training, coaching and diagnosis.... without a time limit, In depth with as much detail as needed .

.

When we finally get the situation solved, please select the 'finish and rate your expert link' near the top of your page and click on it.

.My goal is to give you the best experience possible! I hope I have earned a 5 star rating! Please remember to rate my service by selecting the 5 stars at the top of the screen before you leave today.

If you need more assistance, please use the reply box and let me know.

If the inducer fan starts but nothing else happens, no faint clicks, then the pressure switch needs service or is bad.

.

If the inducer fan does not start at all, then the thermostat, inducer fan, printed circuit board or 24volt caontrol circuit is the problem, you will need a multi meter to discover that, i will coach you.

.

If any or all of that is beyond your skills set range, then tell me which direction you are from the center of the nearest city and i will locate a well rated service outfit for you.

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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 9,718
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Experience: Retired HVAC/ Electrical & Boiler contractor. Industrial

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