A heat pump is one of the most efficient ways to heat and cool your home, but like any system, it can sometimes fail when you least expect it. If you find your heat pump not turning on, don’t panic. Many issues have simple explanations and fixes. Below, we’ll walk through the most common causes and what you can do to restore comfort.
Thermostat Problems
One of the most frequent reasons for a heat pump not turning on is thermostat trouble.
- Check the settings: Make sure it’s set to “Heat” or “Cool,” not just “Fan.” If it’s set to Emergency Heat, your pump may not engage during mild weather.
- Look for a blank screen: If the screen is blank, replace the batteries or check thermostat wiring.
- Compatibility issues: Not all thermostats work with heat pumps. If you recently installed a new one, confirm it’s compatible.
If your thermostat is outdated or unresponsive, upgrading to a smart thermostat designed for heat pumps can improve efficiency and comfort.
Power Supply Issues
If your heat pump won’t turn on at all, it might not be getting power.
- Check the power switch near the unit.
- Inspect the circuit breaker and reset it once if it’s tripped. If it trips again, call a professional.
- Look at the disconnect switch on the outdoor unit to make sure it hasn’t been turned off.
If power issues persist, an HVAC technician should inspect for electrical faults.
Clogged Air Filter or Blocked Airflow
Restricted airflow can cause your heat pump not turning on or shutting down as a safety precaution.
- Replace the air filter every 1–3 months.
- Clear leaves, dirt, snow, or debris around the outdoor unit.
- Move furniture or curtains blocking indoor vents.
Start Capacitor Failure
The start capacitor gives the compressor and fan the extra power they need to start up.
Warning signs:
- Clicking sounds during startup
- Humming noise but no fan movement
- Intermittent starting and stopping
Capacitors are inexpensive but should only be replaced by a professional due to electrical risks.
Frozen Heat Pump
A frozen heat pump not turning on is more common in winter, but it can also happen in summer.
- Wait for the defrost cycle to finish.
- Check for blocked airflow or dirty filters.
- Low refrigerant can also cause freezing and requires professional repair.
If your heat pump stays frozen for more than an hour, call for service.
Compressor Failure
The compressor is the heart of your heat pump. If it fails, your system cannot heat or cool.
Signs of compressor failure:
- The outdoor unit is silent while the thermostat calls for heating or cooling
- Strange noises like rattling, buzzing, or banging
- Air blowing at the wrong temperature
If your compressor fails, you may need to replace it or consider a full system replacement if your unit is over 10 years old.
Faulty Reversing Valve
The reversing valve switches your heat pump between heating and cooling modes.
Signs of trouble:
- Heat pump stuck in one mode
- No response even when thermostat settings are correct
- Hissing noises near the outdoor unit
This repair requires professional service.
Blower Motor Problems
If the blower motor fails, your outdoor unit may run but no air will circulate inside.
- Listen for the blower fan.
- Check the blower belt for damage or looseness.
- Electrical problems may also prevent the blower from working.
Prevent Future Issues with Regular Maintenance
The easiest way to prevent your heat pump not turning on is with regular maintenance.
- Replace air filters every 1–3 months
- Keep the outdoor unit clear of debris
- Schedule professional tune-ups twice a year
- Address unusual noises or performance changes quickly
When to Call a Professional
If you’ve tried the basics and your heat pump still will not turn on, it’s time to call in the experts. At Knowledge HVAC & Refrigeration, our team can quickly diagnose and repair issues like capacitor failures, refrigerant leaks, electrical faults, and compressor problems.
Need Heat Pump Repair?
Contact Knowledge HVAC & Refrigeration today to get your heat pump back up and running.
With extensive expertise in HVAC, Knowledge HVAC & Refrigeration proudly supports homeowners and businesses in Surrey, BC and surrounding areas. Our Red Seal certified technicians are committed to delivering professional, reliable service and high-quality solutions you can count on.
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