Why Is My Heat Pump Not Turning On? Causes & Fixes

A heat pump not turning on can be frustrating, especially when temperatures drop or rise uncomfortably. But before you panic, know that many of these issues have simple fixes you can handle yourself. If the problem is more complex, an HVAC professional can help.

This guide will walk you through the most common reasons why your heat pump not turning on happens, how to troubleshoot the issue, and when it’s time to call in an expert.

Thermostat Issues

Your thermostat is the brain of your heating and cooling system. If it’s not set correctly, your heat pump won’t turn on or respond to temperature changes.

How to Fix It:

✔ Check the settings – Ensure your thermostat is set to “Heat” or “Cool,” not just “Fan.” Also, if it’s set to Emergency Heat, your heat pump may not turn on in mild temperatures.
✔ Look for a blank screen – A dead thermostat screen means it’s not receiving power. Try replacing the batteries or checking the thermostat wiring.
✔ Compatibility issues – If you’ve recently installed a new thermostat, confirm it’s designed to work with heat pumps. Some thermostats only function with traditional HVAC systems.

If your thermostat is outdated or unresponsive, consider replacing it with a smart thermostat compatible with heat pumps for better efficiency and control.

Read More: How Smart Thermostats Save Energy and Money

Power Supply Issues

If your heat pump doesn’t turn on, it may not be receiving power.

Troubleshooting Steps:

✔ Check the power switch – Some heat pumps have a dedicated power switch near the indoor or outdoor unit. Ensure it’s flipped to “On.”
✔ Inspect the circuit breaker – A tripped breaker can cut power to your heat pump that will not turn on. If it’s tripped, reset it once. If it trips again, call an HVAC technician—there may be an electrical issue.
✔ Check the disconnect switch – Outdoor units often have a safety disconnect switch nearby. Make sure it hasn’t been turned off accidentally.

If your heat pump won’t turn on outside after these checks, you likely have an electrical fault that requires professional repair.

Clogged Air Filter or Blocked Airflow

Restricted airflow can cause your heat pump not turning on or shutting down as a safety measure.

How to Fix It:

✔ Replace the air filter – A dirty air filter can block airflow and cause your system to struggle. Change it every 1-3 months for optimal performance.
✔ Clear the outdoor unit – Make sure leaves, twigs, dirt, or snow aren’t blocking the heat pump compressor not turning on. There should be at least two feet of clearance around it.
✔ Check indoor vents – Move any furniture, curtains, or rugs blocking your return air vents to allow proper airflow.

Start Capacitor Failure

The start capacitor gives the compressor and fan motor a boost of power when your heat pump turns on. If it fails, your heat pump won’t turn on and may make a clicking noise.

Signs of a Bad Capacitor:

✔ Clicking sounds when trying to start
✔ Humming noise but no fan movement
✔ Intermittent starting and stopping

Capacitors are relatively inexpensive, but they must be replaced by a professional to avoid electrical hazards.

Frozen Heat Pump

A frozen heat pump not turning on, it is more common in winter but can happen in summer too.

Troubleshooting Steps:

✔ Wait for the defrost cycle – Heat pumps automatically enter defrost mode to melt ice. This usually takes a few minutes.
✔ Check for airflow issues – A dirty air filter or blocked outdoor unit can lead to ice buildup.
✔ Low refrigerant levels – If your heat pump not turning on due to frequent freezing, you may have a refrigerant leak.

If your heat pump remains frozen for more than an hour, call a professional to inspect the system.

Read More: Why Is My Heat Pump Not Heating? Tips for Troubleshooting & Fixes

Compressor Failure

Your heat pump compressor not turning on is one of the most serious problems, as the compressor is responsible for moving refrigerant.

Warning Signs of a Bad Compressor:

✔ The outdoor unit is silent even when the thermostat is calling for heat or cooling
✔ Unusual noises like banging, rattling, or buzzing
✔ The system blows warm air in cooling mode or cool air in heating mode

If your compressor has failed, you have two choices: replace the compressor or install a new heat pump if the system is over 10 years old.

Faulty Reversing Valve

The reversing valve allows your heat pump to switch between heating and cooling. If it gets stuck, your heat pump won’t turn on outside or indoors.

Signs of a Reversing Valve Issue:

✔ Your heat pump is stuck in one mode (heating or cooling)
✔ The system doesn’t turn on, even when thermostat settings are correct
✔ You hear a hissing sound near the outdoor unit

A stuck reversing valve needs professional repair or replacement to restore functionality.

Blower Motor Problems

If your heat pump’s blower motor fails, the outdoor unit may run, but no air will circulate inside your home.

Troubleshooting Steps:

✔ Listen for the blower fan – If the heat pump doesn’t turn on indoors, the issue could be with the motor.
✔ Check the blower belt – A broken or loose belt can stop the blower from working.
✔ Electrical problems – If the blower isn’t getting power, it may need an electrical repair.

Prevent Future Issues with Regular Maintenance

The best way to prevent your heat pump not turning on in the future is with routine maintenance.

✅ Change your air filter every 1-3 months
✅ Schedule professional maintenance twice a year (spring & fall)
✅ Keep the outdoor unit clean and free of debris
✅ Listen for unusual noises and address them early

When to Call an HVAC Professional

If you’ve checked the basics and your heat pump will not turn on, it’s time to call an expert. Professional HVAC technicians in Ontario at LG Home Comfort can quickly diagnose and repair electrical faults, refrigerant leaks, capacitor failures, and compressor problems.

Need Heat Pump Repair?

If your heat pump not turning on is causing discomfort, don’t wait for it to fail completely. Contact LG Home Comfort to get your system running before minor issues turn into major repairs.

Final Thoughts

A heat pump not turning on can often be fixed with simple troubleshooting. Start with the thermostat, power supply, and airflow before moving on to capacitors, refrigerant levels, or electrical issues. If the problem persists, schedule a heat pump service appointment to ensure your system is running efficiently and keeping your home comfortable year-round.

🔥 Need expert heat pump repair? Contact us today! 🔥

Frequently Asked Questions

1. Why is my heat pump not turning on?

Your heat pump may not be turning on due to thermostat misconfiguration, power supply issues, a tripped circuit breaker, a faulty capacitor, or a malfunctioning reversing valve. Checking these common issues can help you identify the problem before calling an HVAC technician. 

2. How do I reset my heat pump if it stops working?

To reset your heat pump, locate the reset button on the outdoor unit, press it, and wait a few minutes before turning the system back on. If the issue persists, check the circuit breaker, thermostat settings, and air filters. 

3. What causes a heat pump to freeze up in winter?

A heat pump can freeze due to restricted airflow, dirty filters, low refrigerant levels, or a faulty defrost board. Ensuring proper airflow and scheduling regular HVAC maintenance can prevent ice buildup. 

4. Why is my heat pump running but not blowing hot air?

If your heat pump is running but not heating, the problem could be a clogged air filter, a malfunctioning blower motor, or a stuck reversing valve. Replacing the air filter and inspecting the blower can help determine the issue. 

5. What should I do if my heat pump keeps tripping the breaker?

A heat pump tripping the breaker may indicate an electrical overload, a shorted compressor, or a failing capacitor. Resetting the breaker can provide a temporary fix, but frequent trips require professional heat pump repair. 

6. When should I call an HVAC technician for heat pump repair?

Call an HVAC professional if your heat pump isn’t turning on, constantly short cycles, makes unusual noises, fails to heat or cool properly, or has frozen coils. Regular maintenance can also help prevent costly heat pump repairs.