Heat Pump Not Cooling – Troubleshooting Tips

| Last Updated: September 13, 2023

There are several annoying heat pump problems, and not cooling is one of the most annoying ones, especially in the summer when both outdoors and indoors may prove too hot for prolonged habitation.

Your heat pump may not cool because of several factors, which may include faulty power supply, restricted airflow, thermostat issues, refrigeration problems, broken valves, or dirty coils.

This article discusses each of the problems above, including various ways to troubleshoot and carry out routine maintenance. Be sure to read through to the end for easy tips.

Reasons Why Your Heat Pump Is Not Cooling and How To Fix Them

As mentioned, there are different reasons your pump is not cooling, and each problem has a unique troubleshooting and fixing process. Below are the common reasons heat pumps stop cooling.

Inappropriate Thermostat Settings

Your heat pump will not cool if the thermostat settings are inappropriate. If the unit is in heat mode, there's no way cooling will happen. Check to ensure that the thermostat is set to cool mode when you want it cool.

The temperature settings on the thermostat may also be the issue. It might be that someone accidentally changed the mode or raised the temperature settings. 

For the best results with cooling, ensure that you set the unit to operate several degrees below the current or prevailing room temperature.

Power Supply Problems

If your heat pump is not cooling your indoor space, you should check to ascertain that the unit has a reliable power supply. 

You might have had the pump working initially, but someone else may have accidentally switched off its mains power supply without knowing that the switch was for the heat pump and not another device or appliance. 

Check to ensure that the switch for the indoor air handler is always on. 

A power problem may also arise from issues with blown fuses or circuit breakers. 

First, check if the main circuit breaker for the house is still in the correct position. If it has tripped, push it back in place and watch for any repeat trippings - which would mean an underlying issue like a short circuit. 

You should also check to see that the heat pump's two breakers haven't tripped - the one for the air handler and the other one for the heat pump condenser. 

If any or both breakers have tripped, restore them to the correct position. Again, watch for any repeat trippings. In this case, trippings could suggest a more serious power problem in your heat pump. As such, the best thing is to call a professional HVAC technician. 

Restricted Air Flow

A dirty air filter usually causes airflow problems. If the thermostat settings are correct and both the indoor and outdoor units are functioning properly with little or no airflow, it could be the trouble of a dirty, clogged filter. 

You can check the amount and cooled state of the air flowing in the system by placing your hand in the vents. If very little air blows or it comes in hot, check if the air filter is dirty or blocked by debris. If it is, ensure you clean or even replace it if it’s damaged or not worth cleaning. 

Faulty Reversing Valve

A heat pump has different valves for regulating the flow of the refrigerant in the system. Each coil has a valve in it. There's also the thermal expansion valve and the reversing valve.

Any of these valves may break down, but it is the reversing valve that usually becomes faulty and makes the heat pump stop cooling. In ideal operations, the valve reverses the pump's refrigerant to work as both an air conditioner and a heater. 

A broken valve requires a qualified HVAC professional to replace it. It might also require refrigerant recharging in some cases. 

Refrigeration Issues

Refrigerant leakages often cause refrigeration issues in heat pumps. They cause the unit to struggle to reach the set temperatures. 

A refrigerant issue may also cause the outdoor unit to freeze, severely limiting its functionality and ability to work in tandem with the indoor air handler for successful cooling. 

If you notice that the outdoor unit is freezing, be sure to call a professional to check for leaks using sensors and pressure equipment. 

Checking and repairing refrigerant issues requires a valid license, which you don't have since you have no training in HVAC-R systems. 

The HVAC technician will let you know what is causing the leakage. It could be that the coil tubing or some other part of the refrigerant path is leaking. 

Dirty Coils

The outdoor and indoor coils may be dirty with caked dust, debris, hair, grass, leaves, strings, and other unwanted items. 

While you can easily clean the outdoor coil with a pressure-free hose, the indoor one is harder to access for easy cleaning. As such, consider calling a seasoned professional. 

Take care when cleaning the coils by cutting the power supply to the unit to avoid the risk of electric shock and short-circuiting the appliance. 


There are several reasons your heat pump may have stopped cooling. It could be a power issue, a broken valve, a low refrigerant charge, dirty coils, restricted airflow, or even incorrect thermostat settings.

The good thing is that you can easily troubleshoot most of the problems and carry out routine maintenance yourself. However, some malfunctions like repeat breaker trippings may indicate deeper underlying issues requiring the services of an HVAC technician. 

People Also Ask

Heat pumps are excellent appliances for heating and cooling your indoor spaces. 

While they may look simple, using them is not as straightforward as you might hope. As such, questions come up around them for which you need an expert's opinion. Here are a few common heat pump questions. 

Do Heat Pumps Have a Reset Button?

Some heat pumps have a reset button that you can use to reboot the unit. The button is usually labeled or color-coded in red. The location and size of the reset button may change depending on the manufacturer or brand, such as Carrier. 

It's advisable to consult the unit's instructions manual to see if your heat pump has a reset button and where it's located.

How To Reset a Heat Pump

Resetting a heat pump can be as easy as locating the reset button and pressing it for about three seconds for the unit to reboot. 

However, if your heat pump does not have a reset button, you can reset the pump in a few steps:

  • Switch off the thermostat

  • Switch of the heat pump's mains power switch

  • Turn off both circuit breakers for the heat pump

  • Waif for 3-5 minutes before switching everything back on, but this time in reverse order. Turn on the two circuit breakers, then the wall switch, and finally the thermostat. 

How Long Do Heat Pumps Last? 

Most heat pumps last between 10 and 15 years. With proper regular maintenance, periodic non-operational times, and appropriate annual repairs, there is no reason your heat pump won't last up to 20 years or more in functional condition. 

However, longevity also depends on other factors, such as the climate, the quality of the unit, and its components.

My name is Bob Wells and I am a retired HVAC tech from Washington state. I am currently retired and no longer do much with HVAC, however, I feel like I have a lot of knowledge in the subject and I wanted to create a website where I could talk about what I've learned and help upcoming HVAC techs. Find more info about me and HVAC Training 101.