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I have a Lennox 80UHG furnace that is blowing cold air. I…

Hi. I have a...

Hi. I have a Lennox 80UHG furnace that is blowing cold air. I have green led indicators flashing. Two of them and are blinking fast. Sometimes it’s only one slow.

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

Brand new filter and double checked the settings.

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

I’m going to try if it’s not a huge deal.

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

That’s it so far.

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Answered in 11 minutes by:
1/18/2018
Gaztech
Gaztech, HVAC Technician
Category: HVAC
Satisfied Customers: 937
Experience: Owner at Gaztech
Verified

Hi I am Gaztech1, a independent technician, I will assist you with your issue.

Don't forget to rate the 5 star rating AT THE TOP OF PAGE if we are done. this will credit me for assisting you.

Here is the list of all the fault code,starts on page 29 to 34 witch one is your furnace giving?

https://www.manualslib.com/manual/824018/Lennox-80ugh.html?page=29#manual

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Customer reply replied 7 months ago
Well I can’t figure it out. Both indicators are blinking fast. The unit was acting fine and then all of the sudden it just blows cold air.

You will need to figure it out somehow.

blowing cold air is because its in lockout

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Customer reply replied 7 months ago
How do I fix that?

You need to figure out the fault code.

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Customer reply replied 7 months ago
Well it tells me that both simultaneously fast flashing means normal operation. Then it goes led 1 off and led 2 slow flash which tells me it might be the pressure switch. Not sure how to trouble shoot it though

Pressure switch is not closing, Check outdoor intake and exhaust pipes for obstruction

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then Try reseting power to furnace , off 10 sec then back on

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Customer reply replied 7 months ago
What does the outdoor intake typically look like?

you should have two 3 inch white plastic pipes sticking out of side of house

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Customer reply replied 7 months ago
Don’t see any obstructions.

then Try reseting power to furnace , off 10 sec then back on

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put thermostat to off first before shuting power off

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Customer reply replied 7 months ago
Should I shut it off at the breaker or the fan switch that shuts power off to the unit?

Breaker

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Customer reply replied 7 months ago
Tried it. Still not working.

OK your pressure switch is stuck closed, you need to remove small hose that goes to the power ventor and blow lightly in tube to unstuck it

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Customer reply replied 7 months ago
Well it definitely did something by doing that. I heard something kick on and my indicators seem to be normal now but still cold air.

Did you put thermostat to calll for heat?

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Customer reply replied 7 months ago
Just reset everything. Indicators are both flashing green fast which indicates normal operation but still no heat.

Did you turn up thermostat?

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Customer reply replied 7 months ago
Just going to call somebody out. Thank you.

Try blowing in and out lightly again in the tube to get pressure switch working.

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You will probably need to relace pressure switch

Don't forget to rate the 5 star rating AT THE TOP OF PAGE if we are done. this will credit me for assisting you.

Best regards

Gaztech1

Gaztech
Gaztech, HVAC Technician
Category: HVAC
Satisfied Customers: 937
Experience: Owner at Gaztech
Verified
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