McKinney, TX Heat Pump Not Cooling? 5 Likely HVAC Causes

Estimated Read Time: 9 minutes

When a heat pump is not cooling, comfort drops and bills rise. If your heat pump not cooling issue just started, you can often pinpoint the cause without guessing. Below are the five most common reasons DFW homeowners lose cool air, plus what you can safely check, and when to call a pro. You will also find a way to save on repair today.

1) Incorrect Thermostat or Mode Settings

Heat pumps pull double duty for heating and cooling. A simple setting can block cool air.

What to check now:

1. Confirm the thermostat is set to Cool and Auto. Do not use On for the fan if air feels warm.
2. Set temperature at least 3 degrees below room temp for a test cycle.
3. Verify any schedule does not override your set point. Disable Hold or vacation mode.
4. Replace thermostat batteries if the display is dim or laggy.

Why it happens:

• Heat and cool modes use the same equipment differently. Wrong mode or fan settings recirculate warm air.
• Smart thermostats can apply energy saver logic that delays cooling.

When to call:

• Short cycling continues after correct settings.
• Thermostat is misreading room temp or losing power. A loose C-wire or failed sensor needs a technician.

Pro tip for North Texas homes: Afternoon sun on west-facing walls can heat the thermostat and cause false readings. Move lamps and electronics that add heat away from the stat.

2) Dirty Outdoor or Indoor Coil Restricting Heat Transfer

Your system must dump heat outside to cool inside. Dirt blocks that exchange and the result is lukewarm airflow.

What to check now:

1. Outdoor unit: Clear leaves, grass clippings, or cottonwood fluff within 2 feet. Rinse the cabinet gently from the inside out if safe access exists and power is off.
2. Indoor coil: Check your filter first. If it is clogged or collapsed, replace it now.
3. Airflow: Open all supply vents and at least 1 return per floor. Closed vents do not boost other rooms. They increase static pressure and reduce system capacity.

Why it happens:

• Spring cottonwood around Dallas and Plano mats to coil fins like felt.
• Construction dust and pet hair load filters fast during remodeling.

When to call:

• Ice is visible on the outdoor lines or indoor coil cover. Turn the system Off at the thermostat and set Fan to On to thaw, then call.
• Coil fins are impacted or bent. A pro cleaning and fin straightening restores heat transfer.

3) Low Refrigerant or a Refrigerant Circuit Fault

Low charge equals low cooling capacity. You may feel cool air that never reaches target temperature.

Signs you might notice:

• Longer run times, poor cooling on hot afternoons, and rising energy bills.
• Hissing at the indoor unit or oily residue on refrigerant lines or coil.
• Ice buildup after short cycles.

What you can do:

• Do not attempt to top off refrigerant. EPA rules limit handling to certified techs.
• Note the pattern. Is performance worse during peak heat or all the time? Share this with your technician for faster diagnosis.

What a pro does:

• Pressure and temperature readings, leak search, and superheat or subcooling verification per manufacturer tables.
• Repair of leaks, then evacuate, weigh in a precise charge, and test operation.

Why On Time Experts helps here:

• We stock common repair parts on our trucks and provide same-day service. Our technicians receive three days per week of training, which shows in faster, accurate fixes.

4) Airflow Restrictions in Ductwork or Blower Assembly

Even with a perfect charge, poor airflow crushes cooling.

Common restrictions:

1. Clogged filter, wrong filter size, or a high-MERV filter that your system cannot handle.
2. Dirty blower wheel and motor that reduce CFM.
3. Leaky or crushed ducts in the attic. North Texas attics get very hot, so leaks pull in superheated air.
4. Closed dampers or furniture blocking returns.

What to check now:

• Replace the filter with the correct size and a MERV rating your equipment supports. Many residential systems perform best with MERV 8 to 11.
• Confirm furniture is not blocking returns. You need 6 to 12 inches of clearance for strong return airflow.

When to call:

• Rooms are uneven, or you hear whistling at a few vents.
• Dust streaks along duct seams suggest leakage. Duct sealing can lift comfort and reduce bills.

Bonus value: Our Revitalizer maintenance includes a complete 47-point diagnostic inspection, lubrication of moving parts, filter replacement, and new thermostat batteries. After these steps, we recalibrate your system to factory specifications.

5) Control, Defrost, or Reversing Valve Issues

A heat pump cools by reversing the refrigerant flow. Control problems block that switch.

Symptoms:

• Outdoor unit runs, indoor air is not cold.
• The system clicks but does not change modes.
• The outdoor fan stops in cooling, then restarts, and you hear unusual buzzing.

What happens inside:

• The reversing valve may be stuck. Low voltage control faults or a weak coil can prevent the valve from shifting into cool.
• Defrost control problems can leave the system in the wrong state after a cycle, especially after heavy rain or temperature swings.

What a pro checks:

• Low voltage control signals, coil resistance, and refrigerant pressures during a forced mode change.
• Electrical connections, contactor condition, and capacitor values under load.

If your heat pump not cooling problem lines up with these signs, schedule service. Our same-day promise gets your comfort back quickly.

Quick DIY Checklist Before You Call

1. Thermostat on Cool, set 3 degrees below room temp.
2. Replace or confirm a clean filter.
3. Clear 2 feet around the outdoor unit and rinse gently if dirty.
4. Open all vents and verify returns are not blocked.
5. If you see ice, turn the system Off, Fan On, and call for service.

How Maintenance Prevents Most No-Cooling Calls

A small tune-up solves small losses before they grow into emergency failures.

What we do during a heat pump maintenance visit:

• "System Cleaning: We’ll clean and inspect the system’s components, ensuring optimal airflow and efficiency."
• "Performance Checks: Our technicians will check for refrigerant levels, inspect electrical connections, and test the thermostat to ensure your system is working correctly."
• "Preventative Care: We identify potential issues before they become costly repairs."

Added protection with our Revitalizer visit:

• "Revitalizer maintenance services include a complete 47-point diagnostic inspection, lubrication of all moving parts, furnace filter replacements, and new battery installation."
• After our techs complete the Revitalizer steps, they recalibrate your heating system to factory specifications.

Two hard facts you can trust:

• We operate with licenses TACLB26616E and M-41383 and pull required permits for installs.
• We guarantee same-day service. If we are late, your repair is free.

When Repair Beats Replacement, and When It Does Not

Repair first makes sense when:

• Your system is under 10 years old, parts are available, and issues are minor, like a capacitor or contactor.
• Ductwork is sound and the home’s cooling load has not changed.

Consider replacement when:

• The compressor is failing, there are repeated refrigerant leaks, or repair costs exceed 30 percent of a new system.
• You want higher efficiency or ductless zoning for stubborn rooms.

What we do on installs:

• Technician inspects ductwork; Identifies unit locations; Installs the outdoor unit; Installs the indoor unit; Connects refrigerant electrical lines; Conducts system testing and calibration; Seals ductwork, if needed; Final inspection and sign off.

We install and service air-source, ductless mini-split, geothermal, hybrid, and absorption heat pumps. Financing is available on approved credit with transparent pricing before work starts.

Local Tips for DFW Homes

• Keep shrubs trimmed back 2 feet around the outdoor unit. North Texas storms push debris into cabinets.
• In spring, cottonwood and oak pollen clog fins fast. Rinse the outdoor coil gently monthly during peak fluff.
• Attic temps soar in July. Check that attic hatches close tightly to prevent hot air infiltration into hallways and returns.

How On Time Experts Handles Your Call

1. Real person answers 24/7.
2. We provide a firm arrival window with same-day service guaranteed.
3. Your technician explains findings, shows photos or readings, and gets your approval before work.
4. We stock common parts to finish most repairs during the first visit.
5. You get options: repair today, plan a Revitalizer, or quote a replacement if it is the smarter long-term move.

Special Offer: Save $77 on Heat Pump Repair

Heat pump not cooling? Get same-day service and save $77 on AC or heating repair. Offer valid through November 5, 2025. Transparent, up-front pricing and a written guarantee. Call (469) 336-3435 or schedule at www.theontimeexperts.com.

What Homeowners Are Saying

"Dominic not only was pleasant and knowledgeable about my HVAC system but he made me feel as though he had my interest at heart... his responses to my questions were spot on."
–Rodney B., Heat Pump Service

"Collin Breen was very friendly, helpful and provided excellent service. Thank you for your assistance in repairing the heat pump."
–R A., Heat Pump Repair

"Technician Dominic was friendly and kept me informed of everything he was doing to find the problem with my heat pump. I was very impressed and satisfied."
–Brenda P., Heat Pump Repair

"Our service technician was Maurice. He was professional, knowledgeable, thorough, and a very nice gentleman. Our heat/air unit is running Great!"
–R S., Heat Pump Service

Frequently Asked Questions

Why is my heat pump running but not blowing cold air?

Wrong thermostat mode, a dirty coil, or low refrigerant can cause warm airflow. Check your thermostat and filter first. If ice forms or airflow is weak, turn it off and call a pro.

Can a dirty filter stop a heat pump from cooling?

Yes. A clogged filter reduces airflow, which lowers capacity and can freeze the coil. Replace filters every 1 to 3 months, faster during allergy or construction season.

How do I know if my heat pump is low on refrigerant?

Look for long run times, poor cooling during hot afternoons, and ice on lines. Only a certified technician can confirm with pressures and temperature readings.

How often should a heat pump be serviced in DFW?

Schedule maintenance at least once a year. Spring is ideal for cooling checks. Our Revitalizer adds a 47-point diagnostic and recalibration.

Is it worth repairing an older heat pump?

If the repair is small and the system is under 10 years old, repair often wins. For major issues like a failing compressor or repeated leaks, consider replacement.

Wrap Up

A heat pump not cooling usually comes down to settings, airflow, dirt, refrigerant, or controls. Start with the simple checks above, then book a same-day visit if comfort does not return. For fast relief in Dallas Fort Worth, On Time Experts has you covered with training, permits, and guarantees that protect your home.

Ready to Get Cool Again?

Call (469) 336-3435 or schedule at www.theontimeexperts.com. Ask for the $77 OFF AC or Heating Repair special. Same-day service is guaranteed, or your repair is free.

About On Time Experts

On Time Experts is DFW’s trusted HVAC team for heat pump repair, installation, and maintenance. Same-day service is guaranteed, or your repair is free. Our certified techs train three days a week, follow permits and code, and arrive with common parts. We stand behind our work with written guarantees and transparent pricing. Licenses: TACLB26616E, M-41383. Ask about our Revitalizer maintenance and Front of the Line Family membership.