Why Is My Heat Pump Not Cooling? 
You’ve got air coming through the vents. The outdoor unit’s humming along. Everything sounds fine except the thermostat reads five degrees above where you set it. We get calls about this constantly at Total Air and Heat in Plano, TX, usually from folks who assume the system’s broken. Sometimes it is. More often, the heat pump’s running just fine mechanically, but something’s stopping it from actually cooling the air. Here’s what’s usually behind it, starting with the cheapest fix and working up.
A Clogged Filter Chokes Airflow
This is the first thing I check on every service call, and it’s the one that surprises homeowners the most.
A heat pump needs steady airflow across the indoor coil to pull heat out of your house. Pack that filter with dust and pet hair, and the system can’t move enough air to do its job. You’ll notice the unit running longer than usual, sometimes nonstop, while the house barely cools at all.
I had a customer over near Los Rios Park in Plano last summer who was convinced her compressor was shot. Pulled the filter and it looked like a gray felt blanket hadn’t been changed in over a year. New filter, and the system caught up within an hour.
Check yours first. If it’s dirty, swap it for the right size and rating, then give the system time to catch up before assuming the worst.
Low Refrigerant Leaves the Air Barely Cool
Refrigerant is what actually carries heat out of your home. Without enough of it, the system blows air that’s only a little cooler than the room not the crisp, cold air you’re used to.
Low refrigerant almost always means a leak. It doesn’t just run low on its own over time. I’ve seen units running nearly around the clock, thermostat never satisfied, because the charge dropped and nobody caught it until the electric bill doubled.
Watch for ice on the copper lines, a hissing or bubbling sound near the unit, or cycles that seem to run forever without the house cooling down. None of these fix themselves, and topping off refrigerant without finding the leak first just means you’re back here again in a few months.
This one needs an EPA-certified technician with gauges not a DIY fix.
A Frozen Coil Stops Cold Air in Its Tracks
Ice on an air conditioner in the middle of a Texas summer sounds like a joke, but it’s one of the most common calls we get.
When the indoor coil ices over, air can’t pass through it. The blower keeps running, vents keep pushing air, but none of it’s actually cold. Usually it’s caused by the same things above a dirty filter, low refrigerant, or blocked vents piling up until the coil finally freezes solid.
If you see ice, shut the whole system off and flip the thermostat fan to “On” so it can thaw. That usually takes two to four hours, sometimes overnight for a bad freeze. Don’t chip at the ice or run the system to try to melt it faster that’s how you crack a coil.
Once it’s thawed, get someone out to find what caused it before you turn the cooling back on.
Thermostat Settings Cause More Calls Than You’d Think
Half the “my system’s broken” calls I run turn out to be a setting, not a mechanical problem.
I’ve shown up to homes where someone accidentally bumped the thermostat to “Heat” during a cool morning and nobody noticed until the afternoon. Or the fan’s set to “On” instead of “Auto,” so air blows constantly even when the compressor isn’t cooling anything.
Before calling anyone, make sure that cooling mode is selected, and the set temperature is below room temperature, the fan’s on “Auto,” and the batteries are fresh if it runs on batteries.
It takes sixty seconds to check. I can’t tell you how many service calls in Plano, TX end with me flipping one switch and heading back to the truck.
Don’t Let It Run Like This for Long
If your system’s running nonstop and the house still isn’t cooling down, don’t wait on it that’s usually how a reasonably priced fix turns into an expensive one. Give us a call and we’ll find the actual cause instead of guessing. We’ve been your trusted next-door neighbor for 65 years, and we’d rather get it right the first time.
FAQ
My heat pump’s running but blowing warm air, what’s going on?
Usually it’s low refrigerant, a dirty filter, a frozen coil, or the thermostat set wrong. Sometimes it’s a failing compressor. A tech can narrow it down in about 30 minutes with the right gauges.
Is it normal for it to run all day in summer?
Longer cycles are normal once it’s hot, especially during a Texas summer stretch of triple digits. But if the house never actually reaches your set temperature, something’s off and it’s worth having looked at.
Can a dirty filter really cause this?
Yes, and it’s the most common cause we see. A clogged filter chokes airflow, which can drop cooling output or even freeze the coil solid, making a simple fix look like a major failure.
How often should I change the filter?
Every one to three months for most homes. If you’ve got pets or run the system constantly through summer, check it monthly a $10 filter beats a $1,500 coil replacement.
Should I keep running it if it’s not cooling?
No. Shut it off and call for service. Running a system that isn’t cooling properly just adds strain on the compressor and electrical parts, and usually turns a small repair into a bigger one.
If the system’s running and the house isn’t cooling, don’t tough it out that’s how a filter change turns into a compressor job
