November 3, 2025
Jean NV Heat Pump Not Cooling? 5 HVAC Fixes
Estimated Read Time: 10 minutes
Is your heat pump not cooling when you need it most? In the Las Vegas Valley, a heat pump not cooling can turn a normal day into a heat emergency. This guide explains the five most common causes, how to troubleshoot them safely, and when to call a pro. You’ll also see local tips for desert dust, extreme heat, and monsoon winds, plus ways to save with current offers and our no-breakdown guarantee.
1) Thermostat or Mode Settings Are Wrong
When a heat pump stops cooling, start with the thermostat. A single setting can sabotage the whole system.
- Confirm it is set to COOL, not HEAT or EMERGENCY HEAT.
- Set the fan to AUTO. ON can make air feel warm between cycles.
- Lower the setpoint at least 3 degrees to force a cooling call.
- Check scheduling. An energy-saving program may be overriding your changes.
- Replace low batteries if your thermostat uses them.
Las Vegas homes often use smart thermostats to manage energy bills during peak heat. If Wi-Fi drops or the app updates, schedules can shift without you noticing. Also verify the indoor temperature sensor is not in direct sun or near a heat source.
When to call a pro:
- The display is blank or keeps rebooting.
- You see wiring errors after recent remodeling or low-voltage work.
- The outdoor unit never starts even though the thermostat calls for cooling.
2) Clogged Air Filter or Dirty Indoor Coil
Restricted airflow is the most common reason a heat pump struggles to cool.
- Dirty filters choke airflow, reduce capacity, and cause ice on coils.
- In our desert climate, dust and construction debris clog filters faster, especially during monsoon season.
- A matted return grille or closed supply registers can starve the system.
What to do now:
- Replace a 1-inch filter every 30 to 60 days. High-MERV filters clog faster.
- Keep at least 80 percent of supply registers open to avoid static pressure spikes.
- If you see frost on the indoor coil or refrigerant lines, turn the system OFF and the fan to ON for 60 minutes to defrost. Then retry COOL.
If ice returns, the evaporator coil may be dirty or you may have a refrigerant problem that needs professional attention.
3) Low Refrigerant or a Leak
A heat pump depends on precise refrigerant charge. Too low and it loses cooling power, runs longer, and can freeze the coil.
Signs to watch:
- Warm air from vents after a short burst of cool air.
- Ice on the outdoor or indoor unit.
- Hissing or bubbling at line sets or the indoor air handler.
Refrigerant is not a “top-off” item. A proper repair includes leak detection, fixing the leak, evacuating the system, and recharging to manufacturer specs. In Clark County, that requires EPA-certified handling. Running undercharged can damage the compressor, a costly part.
Local tip: Many Las Vegas homes have long rooftop line sets that see intense sun. UV exposure and vibration at roof penetrations can accelerate wear on insulation and fittings. Addressing worn insulation improves efficiency, especially in July and August.
4) Outdoor Unit Blocked or Fan Problems
Your outdoor unit must breathe. When airflow around the coil is blocked, heat cannot leave the refrigerant, and indoor air will never cool.
Check these items:
- Clear 2 feet of space around the outdoor unit. Remove yard bags, pool toys, or windblown debris.
- Hose off coil fins gently from the inside out to remove dust. Avoid high pressure.
- Listen for the condenser fan. If the compressor hums but the fan does not spin, turn the system off and call for service to prevent overheating.
In the Valley, landscaping rock and dust can pack into fins. After wind events, many calls we see are simply blocked coils and overheated fan motors. A professional cleaning restores heat rejection and reduces run time.
5) Defrost Board, Sensors, or Reversing Valve Faults
Heat pumps cool by running the refrigerant circuit in one direction and heat by reversing it. If the system is stuck in heating mode or the control board misreads sensors, cooling suffers.
Common culprits:
- Failed defrost control board reading bad coil temperatures.
- Faulty outdoor ambient sensor, especially after extreme heat.
- Stuck or failing reversing valve that will not shift into cooling.
These issues look similar to low refrigerant, which is why proper diagnostics matter. Our technicians test sensor resistance, check coil temperatures, verify reversing valve operation, and confirm correct electrical sequences before replacing parts.
“The new HVAC system is silent when not running and barely noticeable when it is running. It has been 1 month now, everything is running perfectly still, and we could not be happier.”
Quick DIY Checks Before You Book Service
- Power cycle the system at the thermostat and the outdoor disconnect. Wait 5 minutes for pressure equalization.
- Verify breakers are ON. Outdoor and air handler circuits are often on separate breakers.
- Clean or replace the air filter and open closed registers.
- Inspect thermostat settings and schedules.
- Clear debris from the outdoor coil and ensure the fan spins freely.
If these steps do not restore cooling, schedule a diagnostic to avoid compressor damage.
When to Call a Pro in Las Vegas
Call right away if you notice the following:
- Ice on refrigerant lines or the indoor coil.
- Burning smell from the air handler or outdoor unit.
- Outdoor fan not spinning while the compressor is loud or hot to touch.
- Short cycling every 2 to 3 minutes.
Why call Sierra Air Conditioning & Plumbing:
- Same-day service when you book by 6 PM and no dispatch fees.
- $79 heat pump repair diagnostic with the diagnostic fee waived if we do the repair.
- EPA-certified, background-checked technicians who are trained for rooftop and split systems common in Henderson, Summerlin South, and North Las Vegas.
“Adrian and Omar were fantastic. They completed the HVAC install under extreme heat in minimum time. Extremely professional. Would highly recommend Sierra Air Conditioning and Heating.”
How Preventive Maintenance Stops No-Cooling Emergencies
Regular tune-ups keep airflow strong, refrigerant charge correct, and electrical components within spec. That means fewer breakdowns during triple-digit days.
What a professional tune-up includes:
- Clean or replace filters and check static pressure.
- Wash indoor and outdoor coils and straighten fins if needed.
- Test capacitor values and contactor condition.
- Check blower wheel cleanliness and motor amperage.
- Verify refrigerant charge using superheat/subcool methods.
- Inspect and tighten electrical connections.
- Confirm defrost controls and sensors.
Hard fact: Our $149 Heat Pump Tune-Up includes a no-breakdown guarantee for 6 months. If your system fails within that window, we return to diagnose at no cost, give you priority scheduling, and credit your original maintenance fee toward the repair.
“It was a pleasure to meet and work with Daniel today. He was thoughtful and thorough in service and communication. We are very satisfied with his visit today.”
Should You Repair or Replace?
Consider replacement if any of the following is true:
- Your system is older than 12 to 15 years and uses outdated technology.
- The compressor is failing or the coil leaks and parts are scarce.
- Your repair estimate exceeds 30 to 40 percent of the cost of a new, efficient unit.
Benefits of a new heat pump in our climate:
- Higher SEER2 ratings lower summer bills.
- Variable-speed compressors maintain comfort during extreme heat.
- Quieter operation and better humidity control.
Hard fact: We offer heat pump installations for as low as $199 per month with a free estimate and financing options, subject to approval.
Local Factors That Hurt Cooling in the Valley
- Dust and construction debris clog filters and coils faster than average.
- Direct sun on outdoor units and rooftop installations increases head pressure.
- Monsoon winds push debris into condenser fins.
- Attic temperatures soar, stressing air handlers and ductwork.
Your action plan:
- Replace filters on a 30 to 60 day cycle in summer.
- Schedule coil cleanings before peak season.
- Seal and insulate ducts to reduce heat gain.
- Add a smart thermostat and set realistic setpoints during peak hours.
Why Homeowners Choose Sierra for Heat Pump Service
- Since 1987, we have delivered reliable HVAC in Clark County.
- BBB A+ rated, Lennox Premier Dealer, and Best of Las Vegas winner.
- Thousands of five-star reviews and trusted by major retailers.
- No dispatch fees, straightforward pricing, and same-day availability when you book by 6 PM.
- SAM maintenance members receive priority calls, same-day parts replacement on eligible repairs, four annual visits, and 15 percent off repairs.
Your comfort is protected by our 100 percent satisfaction guarantee.
Special Offers for Las Vegas Homeowners
- Special Offer: Heat Pump Install for as low as $199 per month with a Free Estimate. Call (702) 344-1079 before 2025-11-05.
- Special Offer: $149 Heat Pump Tune-Up with a 6-month No-Breakdown Guarantee. Book by 2025-11-05.
- Special Offer: $79 Heat Pump Repair Diagnostic with Same-Day Service. If we do the work, we waive the diagnostic charge. Expires 2025-11-05.
Schedule now at https://sierracoolslv.com/ or call (702) 344-1079. Same-day service available when you book by 6 PM.
Frequently Asked Questions
Why is my heat pump running but not blowing cold air?
Wrong thermostat mode, a dirty filter, or low refrigerant can cause warm airflow. Start with filter and settings. If the outdoor fan runs but air is still warm, schedule a diagnostic.
Can a dirty filter make my heat pump freeze up?
Yes. Restricted airflow drops coil temperature and creates ice. Replace the filter, defrost by running FAN only for an hour, then try COOL. If ice returns, call for service.
How often should I change filters in Las Vegas?
In summer, every 30 to 60 days for 1-inch filters. Desert dust and construction nearby can shorten that window. Inspect monthly and replace when dirty.
Is it safe to hose off my outdoor unit?
Yes, gently. Turn power off, then rinse from inside out. Avoid high pressure that can bend fins. If heavy dust remains, schedule a professional cleaning.
When should I replace instead of repair?
If the system is 12 to 15 years old, has a failing compressor, or repairs exceed 30 to 40 percent of replacement cost, consider upgrading to a high-efficiency unit.
Bottom Line
A heat pump not cooling usually comes down to settings, airflow, refrigerant charge, outdoor airflow, or a control fault. In the Las Vegas Valley, dust and extreme heat make maintenance even more important. If your heat pump not cooling persists, our EPA-certified team will diagnose the root cause the same day you book by 6 PM.
Ready for Fast Relief?
Call Sierra Air Conditioning & Plumbing at (702) 344-1079 or schedule at https://sierracoolslv.com/.
- Use code: $79 Heat Pump Repair Diagnostic. We waive the fee if we do the repair. Expires 2025-11-05.
- Or book a $149 Heat Pump Tune-Up with our 6-month no-breakdown guarantee.
Get same-day service in Las Vegas, Henderson, North Las Vegas, Summerlin South, and beyond. Your comfort is one call away.
About Sierra Air Conditioning & Plumbing
Since 1987, Sierra Air Conditioning & Plumbing has served the Las Vegas Valley with award-winning HVAC service. We are BBB A+ rated, a Lennox Premier Dealer, and multi-year Best of Las Vegas winners (Gold 2020, Silver 2019 and 2021). Homeowners choose us for same-day service when you book by 6 PM, no dispatch fees, clear pricing, and our 100% satisfaction guarantee. Thousands of 5-star reviews and trusted partnerships back our promise: Service that soars above the rest.