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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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My 23 year old ***** ***** furnace runs 15-20 minutes. It

Customer Question

Customer: My 23 year old ***** ***** furnace runs for about 15-20 minutes. It turns off even though not to temp. Check thermostat voltages and the voltages on the wires are red 27v, white 27v, yelow 0v. cycles off after 15-20 minutes and shuts off but voltage on thermostat is the same. If I turn it off by turning the temp down the white goes to 0. I'm guessing the problem is with the furnace. 3 days ago I had to work on the furnace. It had a drip from the air intake fan box down to the gang plug above the board. re-sealed the box and had a huge build-up of water in the hoses to the drain. No water was going through to the drain. Put a vacuum on the drain and sucked out 23 years of dust, dirt, bug parts etc. fluids now drain throughout. Replaced the board last year. The air intake fan motor gets fairly hot but I tried putting a fan on it and it keeps it pretty cool but the cycle doesn't last any longer. Larry
JA: Thanks. Can you give me any more details about your issue?
Customer: Even though I set the thermostat at 71 it never runs long enough to get there. It must be running through the night to stay around 65/66. It must be cycling on it's own over longer OFF times trough the night. Larry
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Submitted: 1 year ago.
Category: HVAC
Expert:  gotoman for ac replied 1 year ago.

That model furnace may may not have diagnostic codes. Install a thermometer in supply duct closest to the furnace and read temp. It should be around 105 to 110 if room them is about 70. Check it a couple time to see if the temp drops off any. I will pull manual on furnace. Russ

Expert:  gotoman for ac replied 1 year ago.

Model number blocked out can you reply with model number. Russ

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