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Why Your Heat Pump Won’t Switch to Cooling Mode


A heat pump operates similarly to an air conditioner: it circulates refrigerant between indoor and outdoor units, absorbing heat from inside a house and then releasing it to the outside. The difference between a heat pump and an air conditioner, however, is that a heat pump can change the direction it moves refrigerant. When the refrigerant cycles in the reverse direction, the heat pump absorbs heat from the outside and releases it to the inside, providing warmth.

It’s easy to switch a heat pump from heating to cooling when warmer weather arrives: you just set the thermostat to “cool” and adjust the temperature. The heat pump will take it from there. However, you may find yourself at the start of the season with a heat pump that won’t start cooling. Either it stays in heating mode or it only sends out room temperature air. What’s happening?

Broken Reversing Valve

A common cause of this problem is a broken reversing valve. This valve is a key component that allows a heat pump to work as a heater and AC. It’s housed in the outdoor unit of the heat pump. Refrigerant from the compressor moves into the reversing valve after the refrigerant is compressed into a high-pressure gas. Depending on the reversing valve’s position, the refrigerant will either move first to the outdoor coils or the indoor coils. If the refrigerant goes to the outdoor coils first, the heat pump will operate in heating mode. If it goes to the indoor coils first, the heat pump will operate in cooling mode.

The reversing valve can become stuck in one position so that the heat pump can’t switch modes. You’ll need to have a professional handle the repair for this, either fixing the valve or replacing it.

Lost Thermostat Connection

The reversing valve may be working fine: the problem is that the thermostat has lost its connection to the valve. The thermostat is responsible for sending the electric signal that energizes the valve and makes it change positions. If the thermostat can’t communicate with the reversing valve, the heat pump will remain in one mode regardless of how you set the thermostat. Professional technicians can have this repaired.

Miscalibrated Thermostat

It’s possible the reason the heat pump won’t change to cooling mode is that the thermostat hasn’t registered that it’s hot enough. A thermostat miscalibration can lead to the thermostat reading the indoor temperature as cooler than it is so it won’t turn the heat pump to cooling when you want it to. HVAC professionals can solve this by recalibrating the thermostat. 

There are several other possibilities, such as low refrigerant levels, electrical problems, or even a broken compressor. You’ll need to have professionals examine the heat pump to find the source of the malfunction and fix it.

If you need a repair for your heat pump in Los Banos, CA, call Purl’s Sheet Metal & Air Conditioning. We have many decades of experience keeping homes comfortable in all kinds of weather. We’ll provide you with the heat pump that will fix and make your home comfortable once more.

Reach out to Purl’s Sheet Metal & Air Conditioning for heat pump service. Uncompromised Quality & Customer Service Since 1952.

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