How to Fix a Heat Pump: Common Problems & Quick Fixes

If you’re trying to fix a heat pump that suddenly won’t heat, won’t cool, or just seems “off,” you’re not alone. We get calls like this all the time at Pointer Cooling and Heating, and honestly, most heat pump problems follow a predictable pattern. The good news? A lot of issues can be identified quickly, and some can even be fixed with a few safe checks (no heroics required).

Below is the same troubleshooting flow we use in the field.

First Things to Check Before Troubleshooting

Before you assume the system is dead, start with the simplest checks.

• Thermostat setting: Make sure it’s set to Heat or Cool, not Off.

• Temperature setpoint: Raise or lower it 2 degrees and wait 5-10 minutes to see if the system responds.

• Fan setting: “Auto” is usually the correct setting.

• Batteries: If your thermostat uses them, replace them.

• Breaker/disconnect: Check the HVAC breaker AND the outdoor disconnect.

A surprising number of “system failures” turn out to be incorrect thermostat settings.

Also, if your thermostat is blank or acting weird, that’s a big clue. In fact, it’s worth reading our post on how to tell if your thermostat is bad before you chase anything else.

How to Fix a Heat Pump That Won’t Turn On

A heat pump that won’t start is usually caused by power or control issues.

Common Causes

• Tripped breaker

• Float switch triggered (overflow protection)

• Thermostat wiring issue

• Blown fuse on the control board

Safe Homeowner Checks

• Reset the breaker once

• Make sure the condensate line isn’t overflowing (more on that soon)

• Confirm thermostat has power

If it still won’t start, stop there. Electrical testing should be done with proper tools and training.

How to Fix a Heat Pump Blowing Cold Air in Heating Mode

This is one of the most common complaints we hear.

Sometimes it’s normal (during defrost). Other times it means the system isn’t heating correctly.

What Could Be Happening

• Heat pump stuck in cooling mode

• Reversing valve issue

• Low refrigerant

• Outdoor unit iced up

If cold air keeps blowing in heat mode, the heat pump may not be switching into heating mode properly. That can happen from refrigerant issues or a failed changeover component, and it typically requires a professional diagnostic.

How to Fix a Heat Pump That’s Frozen or Covered in Ice

Outdoor heat pumps can frost up in winter. That’s expected. However, thick ice buildup is a problem.

Causes We Often Find

• Dirty outdoor coil

• Poor airflow (dirty filter or blocked vents)

• Defrost cycle failure

• Low refrigerant

What You Can Safely Do

• Turn the system off at the thermostat

• Clear leaves/debris around the unit

• Make sure airflow isn’t blocked

Important: Don’t chip or scrape ice off with tools—you can bend coil fins and damage the unit.

Also, keep in mind that icing problems often start with restricted airflow. A clogged filter can reduce airflow enough to make the system run colder than it should, which can lead to freeze-ups. That’s why the U.S. Department of Energy recommends changing or cleaning heat pump filters about every 3 months (or as recommended), and cleaning the outdoor coils whenever they appear dirty.

Why Your Heat Pump Keeps Running (and Never Catches Up)

When a heat pump runs nonstop, it’s usually fighting one of these battles:

• Dirty filter restricting airflow

• Thermostat miscalibrated

• Duct leakage

• Low refrigerant

• Home heat loss (insulation/windows)

Start with the air filter. If it’s clogged, airflow drops and the whole system struggles.

ENERGY STAR’s maintenance checklist highlights basics like thermostat settings, airflow restrictions, and duct issues—all of which can keep a heat pump running longer than it should.

How to Fix a Heat Pump With AUX Heat or EM Heat Showing

This one matters a lot for both comfort and electric bills.

Heat pumps use backup heat when needed. Depending on your setup, that could be electric heat strips or another heat source. However, homeowners often confuse AUX and EM heat—and that confusion leads to expensive thermostat settings.

Here’s the deal:

• Auxiliary heat = automatic help when the heat pump can’t keep up

• Emergency heat (EM heat) = manual override that bypasses the heat pump

To avoid misunderstandings (and a painful utility bill), we strongly recommend reading our blog on auxiliary heat vs emergency heat. Also, if your thermostat literally says EM Heat, our post on EM heat breaks down what that mode actually does and when it should (and shouldn’t) be used.

One key thing we see all the time is that if you raise the thermostat by more than about 3°F, the system may kick on auxiliary heat strips to catch up.

Because of that, try not to make big temperature swings on the thermostat. Heat pumps usually do better with steady settings, and the U.S. Department of Energy even recommends that heat pump homeowners maintain a moderate setting or use a programmable thermostat designed specifically for heat pumps.

So yes… cranking the thermostat up can cost you.

How to Fix a Heat Pump Leaking Water or Causing Indoor Humidity Issues

Water around the indoor unit usually means the condensate drain is clogged.

That can happen from:

• algae buildup

• debris in the drain

• a cracked drain pan

• frozen coil melting rapidly

A clogged drain can lead to overflowing, water damage, and even humidity problems that make the home feel sticky.

If you see water, shut the system off and call a professional before it ruins flooring or drywall. Trust me—water damage can spread quickly.

When You Should Stop DIY and Call a Pro

We’re all for homeowners learning their systems. But a few situations need a technician:

• Refrigerant leaks or low charge

• Electrical burning smells

• Reversing valve failures

• Repeated breaker trips

• Ice that keeps coming back

If the issue involves refrigerant, electrical problems, or repeat freezing, it’s best to schedule professional heat pump repair before the damage gets worse.

Quick Prevention Tips (So You Don’t Have to Fix a Heat Pump Again Soon)

Once your system is running right, protect it.

• Change filters routinely

• Keep outdoor unit clear

• Don’t raise the thermostat dramatically

• Schedule maintenance before peak seasons

A yearly tune-up is one of the easiest ways to prevent surprise breakdowns and keep efficiency steady.

Final Thoughts

If you’ve tried the safe steps above and still can’t fix your heat pump, call a trained technician to diagnose the problem. At Pointer Cooling and Heating, we troubleshoot these issues all the time, and we can quickly determine whether it’s a thermostat problem, airflow issue, or a mechanical failure.

If you’re in Moncks Corner, SC, or one of the surrounding areas, contact us today—we’ll get your comfort back without the guesswork.

FAQs

Heat pump problems can feel confusing, so here are a few quick answers.

Why is my heat pump blowing cold air?

Short bursts can happen during defrost. Constant cold air usually points to a system issue.

Can I run emergency heat all winter?

You can, but it’s expensive and bypasses normal heat pump efficiency.

How often should heat pump filters be changed?

Many homes need filter changes every 1–3 months depending on dust and pets.

When should I call an HVAC company instead of troubleshooting?

Call if breakers trip, leaks appear, or performance doesn’t improve after basic checks.