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Proudly Serving Yakima, Ellensburg, Cle Elum, and the Surrounding Areas Since 1998


ThermAll Heating, Cooling & Electric Blog

Watch Out for the Ways a Malfunctioning Thermostat Can Affect Your HVAC System


When you need to change the comfort levels in your home, what do you do? You go to the thermostat and make adjustments, either changing the programming or doing a temporary override. That’s just part of life in your home, something you take for granted like turning on light switches and using appliances like the dishwasher.

The thermostat, however, is a complex device. Because it’s connected to the HVAC system that controls your home comfort, any malfunction can lead to unusual heating and cooling behavior. You may not immediately know that the thermostat is the culprit, which is why it’s always best to call for professional HVAC repair in Yakima, WA from our team. We can track down the problem, and if it’s a thermostat issue, we know what to do to fix it.

So What Can Go Wrong With a Thermostat?

There are several thermostat malfunctions that crop up and we’re used to seeing them. We’ll go over the most common ones that will end up affecting your HVAC system so you’ll know what to look for.


This is the most frequent problem that thermostats encounter, and it can happen to all types of models, from old-school manual thermostats to the most advanced Wi-Fi/smart thermostats. The thermostat starts detecting incorrect temperatures, much like an analog watch that has started to slow down.

This will lead to the thermostat activating and shutting off the heating and cooling at incorrect times. Fortunately, this is one of the easiest thermostat problems to fix: our technicians can quickly recalibrate the thermostat to restore it to normal operation.

Incorrect Placement

The placement of a thermostat in a home isn’t a random choice, nor is it done to put it in the most convenient place for people to use. A thermostat must be located in an area where it picks up the average temperature of the home, without external sources of heat and cold affecting it.

A thermostat that’s too far from the center of the house, or which is placed where it receives direct sunlight or cold drafts from windows, will pick up incorrect readings leading to poor HVAC performance. The thermostat will need to be reinstalled in a better position.

Lost Connection

Thermostats have several different connections to the HVAC system, with separate wires to handle turning on and off blower motors, the compressor motor, reversing valves, and activating furnace ignition. Losing one of these connections may cause the HVAC system not to respond at all, or to run continuously. Technicians can make wiring repairs to correct this, although they may recommend replacing the thermostat.

Thermostat-System Mismatch

A thermostat can be mismatched to an HVAC system. For example, an advanced smart thermostat won’t necessarily work with an old HVAC system because the algorithms of the thermostat do not work with the old control board.

This can actually lead to the thermostat damaging the HVAC system. At the very least, it will impair the thermostat’s advanced features from having much if any effect. Please, always rely on HVAC professionals when it comes to selecting and installing a new thermostat so you can avoid this type of problem.

Call ThermAll Heating & Cooling, Inc: We are “Your Home Comfort Hero!” 

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