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My unit seems to be short cycling, and the temperature

Customer Question
My unit seems to...

My unit seems to be short cycling, and the temperature sensor on the unit in the attic has a high temperature light on.

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

All good

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

No

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

The temp differential isn't great, but the weather here is very moderate right now, so it's hard to test

Submitted: 3 months ago.Category: HVAC
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Answered in 10 minutes by:
3/20/2018
HVAC Technician: airheatman, HVAC Technician replied 3 months ago
airheatman
airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 9,181
Experience: Furnace, A/C and heat pump specialist.
Verified

There may be
several limits on the furnace.Below describes locations:
PRI***** *****MIT
The pri***** *****mit control is located on the partition panel and monitors
heat exchanger compartment temperatures. It is a normally closed
(electrically), automatic reset, temperature-activated sensor.
The limit guards against the overheating as a result of insufficient
conditioned air passing over the heat exchanger.
AUXILIARY LIMIT
The auxiliary limit control(s) are located on or near the circulator
blower and monitors heat exchanger compartment temperatures.
They are a normally-closed (electrically), manual-reset, temperature
activated sensors. These limits guard against overheating as a
result of insufficient conditioned air passing over the heat exchanger.
VENT DRAFGAURD
These would be located on the draft hood if you have one on your furnace.
ROLLOUT LIMIT
The rollout limit controls are mounted on the burner/manifold assembly
and monitor the burner flame. They are normally-closed
(electrically), manual-reset, temperature-activated sensors. These
limits guard against burner flames not being properly drawn into the
heat exchanger.
Lets start with the most simple and easy. Look near burners for limits with a little button in center.It will push in to reset.If none are tripped we will go from here. Let me know if you have a multi meter for troubleshooting.

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HVAC Technician: airheatman, HVAC Technician replied 3 months ago
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