AC Thermostat Reading the Wrong Temperature: Placement Is Usually the Cause

The Facts

Thermostat Reads Wrong

What It Usually Is

Thermostat mounted above a heat lamp, a warmer, or a fryer line, reading the equipment instead of the room.
Thermostat on an exterior wall in afternoon sun, or in a draft from a door or a supply register.
Thermostat wire damaged or spliced, giving intermittent readings.
A thermostat that has drifted out of calibration, the least common cause.

Check This First

Hold a second thermometer at the thermostat and again in the middle of the room. Compare.
What is within four feet of the thermostat? Heat lamps, warmers, sunny glass, a register?
Does the system run constantly, or short cycle?

When To Call

The dining room is cold while the thermostat says it is hot.
The unit never shuts off.
Comfort complaints that move with the sun or the lunch rush.

What the Repair Usually Costs

Relocating a thermostat with new wire and reprogramming is a service-call-level job. We quote the number on site.

The diagnostic visit turns that range into a number for your unit, and you approve the number before any repair happens.

Dirty Works technician servicing a rooftop unit

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Need the Documents Today?

Text 601-337-1069 with the certificate holder's legal name and address, or email the vendor form. The W-9 and certificate of insurance come back the same business day.

Text the Request

Common Questions

Thermostat Reads Wrong FAQ

Why was the thermostat put there?

Usually because the wall was convenient when the building was built, before the kitchen layout changed. Equipment moves; thermostats do not.

Where should it go?

An interior wall, away from heat sources, drafts, and sun, at eye height, in the space it is supposed to control.

Will this lower the power bill?

A unit running to satisfy a thermostat above a heat lamp runs far more than it needs to. Moving it usually shows on the next bill.

Thermostat Says 91°F, The Room Says 74°F