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Clawson Heating & Air Conditioning Blog

My Heat Pump Won’t Switch Out of Heating Mode! What’s Wrong?


A heat pump is one of the most convenient home comfort systems available because it can work as both a powerful cooling system and energy-efficient heating system—year-round comfort in a single package. 

But if you discover one day that your home’s heat pump won’t switch over to do half of its job, you’ll be uncomfortable, unhappy, and wondering if you need to schedule heat pump repair.

Since the hot weather is now arriving, you may be in the position when you expect your heat pump to change over to cooling mode and work as an air conditioner. If you turn on your heat pump and the only air you get from the vents is warm air, there are several possibilities for what’s happening. The answer may be simple. Or you may need to call our technicians to examine the heat pump and see what needs to be repaired. Below we’ll look at several examples of what might be wrong.

Thermostat setting mistakes

This may sound obvious, but the obvious is often the first thing people overlook. If this is your first year using a heat pump, make sure you know how to operate the thermostat so it will switch over into cooling mode. Check that the thermostat settings are lower than the outdoor temperature and that the system isn’t in “fan only” mode. Also, check on pre-set programming: an older program may be overriding your new requests for cooling.

Malfunctioning thermostat

The thermostat may actually be broken. If it is sensing incorrect temperatures in your house, the thermostat may turn the heat pump over into heating mode when it should be in cooling mode. Please don’t try to overcorrect a malfunctioning thermostat by pushing the setting way too low—you need experts to repair the thermostat so it does the job it’s supposed to without causing massive power waste or putting too much strain on the system.

Clogged air filter

Checking on the air filter is a standard step we recommend people take whenever they’ve got strange behavior from their heat pump. If the filter for the heat pump is clogged, it will make it hard to cool down enough air. If the air you’re getting from the vents is more room temperature than heated, a clogged filter may be the problem, and all you have to do is put in a clean one.

Broken reversing valve

This is the main cause of a heat pump that’s gotten stuck in one mode. The reversing valve is a critical part of a heat pump that differentiates it from an air conditioner: this valve controls the direction that refrigerant flows through the heat pump, which determines whether it’s in heating or cooling mode. The valve can become stuck, which will trap the heat pump in one mode or the other. It might also lose its connection to the thermostat so that no matter what signal for cooling the thermostat sends, the heat pump won’t respond. You can’t repair a reversing valve yourself. It needs to either be repaired or replaced by a professional.

Clawson Heating & Air Conditioning is “Connecting people to Comfort”! Contact us for heat pump or AC repair in the Greater Portland Area.

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