If your heat pump heats fine, but it doesn’t cool, you have a problem. But don’t panic! Several minor issues can stop a heat pump from cooling, and you can often solve the problem without having to replace your heat pump.
Let’s take a look at the most common issues that stop a heat pump from cooling and how to fix them.
9 Reasons Why Your Heat Pump Isn’t Cooling
1. Thermostat Isn’t Set Right
Sometimes the fix is as simple as checking your thermostat settings. Make sure your heat pump is set to “cool” and that the temperature is low enough.
2. Thermostat Is Malfunctioning
If your thermostat isn’t working properly, it can’t tell your heat pump when to start cooling. This could be due to old wiring, a bad sensor, or something as simple as dead batteries. You might have to install a new one, but replacing your thermostat is a much more affordable fix than replacing your heat pump.
3. Filter Is Clogged
Dirty air filters block airflow, which can make it impossible for your heat pump to sufficiently cool your house. Replacing or cleaning your filter regularly—typically every 1–3 months—can make a big difference in cooling performance.
4. Wiring Wasn’t Installed Correctly
If your heat pump was recently installed or serviced and now it won’t cool, incorrect wiring could be the culprit. Miswired controls or connections can prevent the reversing valve from switching to cooling mode or stop the compressor from running altogether. You will likely need to call a professional to diagnose and repair a heat pump wiring issue.
5. Outdoor Unit Is Blocked
Your outdoor unit needs space and airflow to release heat. If it’s blocked by overgrown plants, toys, patio furniture, or debris, the heat pump will struggle to cool effectively. Clearing the area around the unit and gently cleaning the condenser coil can improve performance.
6. Refrigerant Is Low
Your heat pump relies on refrigerant to transfer heat. If there’s a leak or the system was never charged correctly, your heat pump won’t be able to cool your home on a hot day. Handling refrigerant requires specialized equipment and licensing, so this is a repair for a professional.
7. Reversing Valve Is Stuck
The reversing valve is what allows a heat pump to switch between heating and cooling. If it’s stuck in the heating position, your system will continue producing warm air even when you set it to cool. A professional heat pump technician can figure out why it’s stuck and the best repair.
8. Poor Insulation
Sometimes, a heat pump that doesn’t cool effectively has nothing to do with the heat pump. If your house isn’t well-insulated, outside heat will constantly seep in. That makes it much harder for your heat pump to keep up, and could leave you feeling like it isn’t working properly.
9. Air Leaks
Air leaks are small gaps and cracks in your home’s construction that let air move freely into and out of your house. In a leaky house, cool air will seep right out, forcing your heat pump to work much harder than it was intended to, which can reduce its cooling capabilities. The best way to solve this problem is with air sealing.
When to Repair vs Replace a Heat Pump that Won’t Cool
The right fix for your heat pump depends on the severity of the problem.
If the issue is small, you can fix it yourself (usually at no cost). Start by checking your thermostat settings, clearing away any debris around the outdoor unit, and cleaning the air filter. If that doesn’t work, a professional can help you diagnose the problem.
More serious problems, like low refrigerant, a stuck reversing valve, or wiring issues, require professional attention. In many cases, they can be repaired. But sometimes, it makes more sense to install a new system, especially if your heat pump is getting old.
A general rule of thumb: If your heat pump is over ten years old and the repair cost is more than half the price of a new system, it makes more sense to replace the system. Learn more about when to replace an old heat pump.
Find the Right Heat Pump Fix for Your Home
If you need heat pump help, Total Home Performance is here for you. We fix heat pump problems by looking at your whole house, not just the heat pump. Your HVAC, insulation, and air sealing all work together, and if one’s off, it can impact that whole system. Our whole-home approach finds the real issue and fixes it for good, so you stay cool and avoid repeat repairs.