XV 80 trane cycle

Old 12-05-11, 09:55 PM
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XV 80 trane cycle

I have a xv 80 furnace, it is cycling on and off, thermostat clicks on, burners ignite, runs for 3-5 minutes, then it shut off, cools down, cycle repeats. Four flashs indicate a high temp limit switch. Not the problem, had the repair man out. He says not suffiecent air going around heat exchanger, it gets to hot, and is doing what it is supposed to do. He, thinks it is a blocked cooling tower, not allowing the air out into the ducts. I eliminated this possibility, by taking the cover plate off of the cooling tower, heated air exhausted into hallway, and high temp came on and shut down burners. Tomorrow, will go in the attic and pull off the return air duct, and see if there is an old filter or collapase duct, that maybe restricting the return air.
But, have a seven day programable thermostat, and could swear that I hear this clicking on and also clicking off, about the same time the burner shuts itself off. Is it possible that the thermostat is bad or perhaps not compatible with this unit???
Any suggestions?

Last edited by hvactechfw; 12-06-11 at 03:38 AM.
Old 12-07-11, 06:46 AM
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what speed is the motor on? the guy should have atleast attempted to increase the fan speed, that would solve your problem.
Old 12-07-11, 08:50 AM
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Diagnostic lights are usually a pretty good indicator of a problem. This has also been confirmed by your repairman.

Still, checking to verify that the thermostat isn't shutting off the furnace is worthwhile. When there is voltage to the "W" terminal of the furnace or circuit board, the thermostat is calling for heat. Use an AC voltmeter to check and see if that terminal remains energized when the burners shut off.

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