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My furnace is throwing cold air. Model m801p100cu60aaa.

Customer Question
My furnace is throwing cold...
My furnace is throwing cold air.
Model m801p100cu60aaa. Flashing light blinks 3 times then pauses, blinks three times then pauses... pressure switch problem?
Submitted: 10 months ago.Category: HVAC
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Answered in 2 minutes by:
9/29/2017
HVAC Technician: Phil, Mechanical Engineer replied 10 months ago
Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 9,806
Experience: Retired HVAC/ Electrical & Boiler contractor. Industrial
Verified

Hello, do you hear the small inducer blower start as you set the thermostat to heat? if so, and if nothing else happens after that, it could be a bad pressure switch. Read the following and send me a photo of the wiring diagram, I will mark it up with trouble shooting instructions

.

OPENING STATEMENTS

Important note about RATING my work:

I am a retired mechanical engineer and HVAC/electrical/ refrigeration and boiler contractor ... with 56 years in this business. The last 20 of those years consulting for major firms nationally.. and with over 8,000 questions answered here since 2009, with a 98.5% satisfaction rating.

.

All I ask is please respect me and my input by selecting the***RATING LINK***at the top of your page, that is the only way I am credited through the site. Rating does not affect your charges nor ability to refund if not satisfied.

.

If you need to be coached through a full diagnosis/repair,and wiring etc. for up to two days, and wish to be trained to use test instruments...... that goes well beyond' Just a simple Answer' of course, and goes beyond what most other experts here offer.....rate my answer so far positively.. . and I will deliver that training and coaching to you All on the same dime so to speak.

That said, I cannot guarantee that you will not do something unsafe, or cause damages. You take that risk.

.

Lacking a positive rating I can spend days helping a person at my own expense and loose my shirt, shorts and socks on the deal.

.

Attach a close up photo of the wiring diagram glued to the inside of the blower access door and I will mark it up with trouble shooting instructions then follow up with step by step training and coaching until you have a solution.

.

Photo must be exceedingly well focused. Use the 'add files' link next to your send button to get the photo to me.

.

Phone call offers:

.

Tell me a little about your technical background and instruments on hand so that I can coach you most effectively. We can go from here.

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HVAC Technician: Phil, Mechanical Engineer replied 10 months ago

Hello, click here please. use a multi meter to measure the voltage between R and C terminals marked in yellow. Check that 5 amp fuse.

Then get me a photo of the actual wiring diagram (its a flat sheet of paper about 12" square, and it is glued to the inside of the blower access door, photo needs to be close up, taken straight on, in good light, and it must be *exceedingly well focused.

We can go from there

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HVAC Technician: Phil, Mechanical Engineer replied 10 months ago

Thanks, click here please, I have circled the pressure switch in blue, it should have Orange and Yellow wires attached, its about 4 inches round in most cases, mounted near the small inducer blower. and has one or two 1/4" black rubber tubes attached.

The verify a pressure switch problem fit a jumper wire between is two wire terminals, but do it AFTER the inducer fan has been running for 2 to 7 seconds.. not before, and not much later. If the burner fires we know its a pressure switch problem..

We can do without a multi meter for that test, to go further though you will need one.

.

We can go from there without a time limit, In depth with as much detail as needed , after you rate this answer:

Select the 'finish and rate your expert link' near the top of your page and click on it. Over half of my customers forget to rate my work. That is something like yourself getting a 60% pay cut. Its not sustainable. I hope you understand.

.

OPENING STATEMENTS

Important note about RATING my work:

I am a retired mechanical engineer and HVAC/electrical/ refrigeration and boiler contractor ... with 56 years in this business. The last 20 of those years consulting for major firms nationally.. and with over 8,000 questions answered here since 2009, with a 98.5% satisfaction rating.

.

All I ask is please respect me and my input by selecting the***RATING LINK***at the top of your page, that is the only way I am credited through the site. Rating does not affect your charges nor ability to refund if not satisfied.

.

If you need to be coached through a full diagnosis/repair,and wiring etc. for up to two days, and wish to be trained to use test instruments...... that goes well beyond' Just a simple Answer' of course, and goes beyond what most other experts here offer.....rate my answer so far positively.. . and I will deliver that training and coaching to you All on the same dime so to speak.

That said, I cannot guarantee that you will not do something unsafe, or cause damages. You take that risk.

.

Lacking a positive rating I can spend days helping a person at my own expense and loose my shirt, shorts and socks on the deal.

.

Attach a close up photo of the wiring diagram glued to the inside of the blower access door and I will mark it up with trouble shooting instructions then follow up with step by step training and coaching until you have a solution.

.

Photo must be exceedingly well focused. Use the 'add files' link next to your send button to get the photo to me.

.

Phone call offers:

.

Tell me a little about your technical background and instruments on hand so that I can coach you most effectively. We can go from here.

.

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