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November 3, 2025

Leo-Cedarville Heat Pump Not Cooling? 5 Likely HVAC Causes

Estimated Read Time: 9 minutes

If your heat pump not cooling has you sweating, you’re not alone. When summer humidity hits Fort Wayne, a struggling system can turn uncomfortable fast. Below are the top reasons a heat pump fails to cool, what you can check safely, and when to call a pro. We service all makes and models, offer 24/7 emergency help, and back our work with trusted warranties.

Quick Take: How Heat Pumps Cool

A heat pump moves heat, rather than creating it. In cooling mode, it pulls heat from indoor air and releases it outside through the outdoor coil. Good airflow, accurate controls, and a sealed refrigerant circuit are essential. When any of these fail, comfort and efficiency drop.

What you can do first:

  1. Verify the thermostat is set to COOL and the fan to AUTO.
  2. Replace a dirty filter.
  3. Clear debris around the outdoor unit.
  4. Check your breaker panel for a tripped breaker.

If those steps do not restore cooling, the issue likely needs professional diagnostics.

Reason 1: Thermostat or Mode Settings Are Off

Incorrect settings are the fastest way to lose cooling. If the thermostat is on HEAT, EM HEAT, or FAN ON, the system might circulate warm air or never complete a cooling cycle. Battery‑powered thermostats can also misread temperature if batteries are weak or if the device is in direct sunlight.

What to check now:

  1. Set COOL, target 72–76°F to test.
  2. Set FAN to AUTO, not ON.
  3. Replace thermostat batteries if applicable.
  4. Ensure the schedule is not overriding your setting.

When to call a pro:

  • Short cycling, blank screens, or unresponsive controls.
  • Smart thermostat mis‑wiring after a DIY install.

Pro tip for Fort Wayne homes: Many older houses in our area have multi‑wire setups from past upgrades. A mis‑landed O/B reversing valve wire can keep a heat pump from switching modes properly.

Reason 2: Dirty Filter or Blocked Airflow

A clogged return filter or closed supply registers reduce airflow across the indoor coil. Low airflow can cause the coil to get too cold, leading to icing and poor cooling. In extreme cases, you may see frost on the refrigerant lines.

What to check now:

  1. Replace the filter if it looks gray or dusty. Most homes need a change every 30–60 days in summer.
  2. Open and un‑block supply registers. Avoid closing more than 10% of registers.
  3. Look for collapsed flex duct or crushed sections in basements and crawlspaces.

When to call a pro:

  • Visible ice on the indoor coil or refrigerant lines.
  • Repeated icing after a new filter.
  • Signs of duct leakage, such as hot rooms at the end of long runs or dusty returns.

Local note: Cottonwood fluff peaks in late spring around Fort Wayne and can choke both indoor and outdoor airflow. If your system lagged right after that bloom, you may need a professional clean.

Reason 3: Outdoor Unit Can’t Breathe

Your outdoor coil must shed indoor heat to the outside air. Grass clippings, cottonwood seeds, leaves, or a fence placed too close trap heat and cut capacity. A failing outdoor fan motor or damaged fan blade will also reduce airflow and cooling performance.

What to check now:

  1. Keep 18–24 inches of clear space on all sides of the unit.
  2. Gently rinse the coil from the inside out with a garden hose. Do not use a pressure washer.
  3. Ensure the top fan spins strongly and quietly when cooling is on.

When to call a pro:

  • Fan hums but does not spin, or the unit starts and stops rapidly.
  • The coil is matted with debris that won’t rinse away.
  • Repeated breaker trips when the outdoor unit starts.

Why it matters: A blocked coil raises operating pressure and temperature, slashing efficiency and stressing components. A professional deep clean and electrical check restore capacity and protect the compressor.

Reason 4: Refrigerant Leak or Low Charge

Heat pumps depend on precise refrigerant levels. Low charge from a leak causes weak cooling, longer run times, and icing. Overcharge can be just as bad. Refrigerant circuits are sealed; they do not “use up” refrigerant.

Signs you may have a refrigerant issue:

  1. Warm air from vents during cooling mode.
  2. Hissing at the indoor or outdoor unit.
  3. Ice on the outdoor or indoor coil.
  4. High energy bills with poor comfort.

What not to do:

  • Do not try to top off refrigerant without leak testing. That only masks the problem and can harm the environment and your compressor.

What a pro will do:

  • Perform leak detection and repair, evacuate and weigh in the charge to manufacturer specs, verify superheat/subcooling, and test operation under load.

Good to know: New system installations from reputable providers include manufacturer and labor warranty options. If your system is newer and low on refrigerant, ask about warranty coverage for parts and labor.

Reason 5: Reversing Valve, Defrost Board, or Control Failures

The reversing valve switches the system between heating and cooling. If it sticks or its solenoid fails, the unit may heat when you want cooling or deliver lukewarm air. Control failures on the defrost board, contactor, capacitor, or sensors can create similar symptoms.

Warning signs:

  1. Unit runs but air is not cool, even with clean filters and coils.
  2. System cools briefly, then reverts to heating or room‑temp air.
  3. Outdoor unit clicks but does not start, or starts with a loud buzz.

Professional fixes may include:

  • Reversing valve diagnosis and replacement.
  • Control board testing and replacement.
  • New contactor, capacitor, or sensor calibration.

In our area, weather swings and spring storms can stress outdoor electronics. Surge issues after lightning or utility events often reveal weak capacitors or contactors.

When Repair vs. Replace Makes Sense

Consider replacement when your heat pump is 12–15 years old, has a failed compressor, or needs repeated refrigerant recharges. Modern systems offer higher SEER2 ratings and better humidity control, which matters in our humid summers.

Replacement benefits:

  1. Lower energy bills and quieter operation.
  2. Improved comfort and better dehumidification.
  3. Fresh warranty coverage for peace of mind.

What to expect from a quality install:

  • Proper load calculation, duct evaluation, and charge verification. Reputable installers provide documented commissioning data and a clear warranty. At Summers, new installs include strong manufacturer coverage and workmanship protections, so you are never left guessing.

Smart Maintenance to Prevent Cooling Problems

Regular maintenance keeps airflow strong, coils clean, and controls tested. A professional tune‑up includes safety checks, electrical testing, refrigerant analysis, and cleaning that typical DIY cannot reach.

Seasonal checklist:

  1. Change filters every 30–60 days in peak use.
  2. Keep outdoor clearance and rinse coils gently in spring.
  3. Schedule a professional tune‑up before summer and winter.

Why it pays:

  • Catching a weakening capacitor or contactor early prevents mid‑summer breakdowns. Our maintenance packages include a No Breakdown Guarantee on tune‑ups, so if your system fails after service, we make it right.

Local Insight: Fort Wayne Homes and Heat Pumps

  • Older Fort Wayne homes and farmhouses often have mixed ductwork that restricts airflow. A static pressure test during maintenance can reveal hidden duct bottlenecks.
  • Cottonwood and mowing season clog outdoor coils quickly. A spring cleaning visit after the bloom helps keep SEER2 performance closer to rated levels.
  • We service Fort Wayne, New Haven, Auburn, Columbia City, Decatur, Kendallville, Bluffton, Huntertown, Zanesville, and Huntington with same‑day and 24/7 emergency options.

When to Call a Professional Immediately

  • Ice on coils or refrigerant lines.
  • Burning smells, repeated breaker trips, or buzzing at the outdoor unit.
  • The system runs constantly but never cools below 78°F.

As a homeowner, simple checks are smart. But sealed‑system, electrical, and control issues require licensed tools and training. Calling early protects your compressor and your comfort.

What Homeowners Are Saying

"Jazmyn came out to my house around 4 in the morning or so for an emergency HVAC issue. No heat in the house is a huge deal at 2 in the morning when you have a baby in the house. I can’t thank her enough for getting my heat pump up and running. I appreciate the team at Summers and will definitely recommend them to all my friends and family. Thank you for the stellar service!"
–Fort Wayne Homeowner
"Today Harold Krieg came out and we had an issue with a leak on the inside unit of our heat pump. Harold explained everything he found and how he was going to fix the problem. This is the second time he has been here but not for the same reason. He does fantastic work and we will use Summers for all our repair work."
–Local Homeowner
"A big Thank You to Devon and Chris who installed our heat pump last week! They did an excellent job, very knowledgeable, explained everything they were going to do! Plus they did an excellent job cleaning up when the job was complete! Very nice and polite guys! We are very happy with Summers! 100% recommended! These guys need special recognition for a job well done!!"
–Area Homeowner
"Called Summers 2 weeks ago for an updated quote on a new heat pump, (our old boiler was probably 40% efficient). Josh A came out, took a look, and put together a good quote for us, we scheduled the work for last Wednesday... I am very appreciative of Summers, and the great work they did."
–Fort Wayne Resident

Frequently Asked Questions

Why is my thermostat showing AUX heat in summer?

AUX heat should not run in cooling. Incorrect thermostat wiring or a stuck reversing valve can cause this. Set to COOL, check the O/B setting, and call a pro if AUX appears.

How often should I replace my heat pump filter in summer?

Check monthly and replace every 30–60 days during heavy use. Homes with pets, construction dust, or allergies may need more frequent changes to protect airflow and comfort.

My outdoor unit is iced over. What should I do?

Turn the system OFF and set the fan to ON to thaw the indoor coil. Do not chip ice. Replace the filter, clear obstructions, then call for service to check airflow and refrigerant.

Is it worth repairing a 13‑year‑old heat pump that’s not cooling?

Maybe. If repairs are minor and the system is efficient, repair can make sense. For major issues like compressor failure or repeated leaks, replacement often saves money long term.

Do you offer 24/7 emergency heat pump service?

Yes. We provide same‑day and 24/7 emergency service across Fort Wayne and nearby cities, with trained and certified technicians who service all brands and models.

Wrap‑Up: Restore Cooling Fast

If your heat pump not cooling is disrupting your day in Fort Wayne, start with simple checks, then call a licensed pro for airflow, refrigerant, or control issues. Summers Plumbing Heating & Cooling offers 24/7 emergency service, full‑coverage warranties on new installs, and a No Breakdown Guarantee on tune‑ups. Call (260) 222-8183 or schedule at https://www.summersphc.com/fort-wayne/.

Ready to Get Comfortable Again?

We service Fort Wayne, New Haven, Auburn, Huntertown, Columbia City, Kendallville, Decatur, Bluffton, Zanesville, and Huntington. Same‑day and 24/7 emergency service available.

About Summers Plumbing Heating & Cooling

For 50+ years, Summers Plumbing Heating & Cooling has served Fort Wayne and nearby cities with licensed, background‑checked, trained, and certified technicians. We offer same‑day and 24/7 emergency service, transparent pricing, and a customer‑first guarantee. New HVAC installs include strong manufacturer and workmanship warranty coverage, and we stand behind our tune‑ups with a No Breakdown Guarantee. Local, reliable, and ready to help.

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