Heat Pump Not Heating / Blowing Cold Air

Common Symptoms

You might be experiencing this problem if you notice any of these signs:

• Heat pump runs but air feels cold
• Outdoor fan runs but no heat inside
• Thermostat shows heating mode but produces cold air
• Auxiliary heat never kicks on
• Slight cool breeze from vents instead of heat
• Heat pump sounds normal but no warmth
• Emergency heat works but normal heat doesn't
• Worked fine in cooling, fails in heating
• Indoor unit runs constantly with no heat output
• Outdoor unit runs but produces no heat transfer

Step-by-Step Diagnosis

Follow these steps to identify the exact cause of your problem:

1. Verify thermostat is set to Heat mode, not Cool
2. Check thermostat temperature set 5 degrees above room temp
3. Confirm heat pump is not in emergency heat mode
4. Listen for reversing valve click when switching from cool to heat
5. Feel air from vents - should be lukewarm at minimum (90-100°F)
6. Check if outdoor unit is running and fan spinning
7. Inspect outdoor unit for heavy ice or frost buildup
8. Verify both indoor and outdoor units are powered on
9. Check if auxiliary heat indicator appears on thermostat
10. Note outdoor temperature - below 25°F affects efficiency
11. Test cooling mode to see if compressor works
12. Check refrigerant lines for temperature difference between supply/return

Most Common Causes (Ranked by Likelihood)

DIY Solutions

Step-by-Step Instructions:

1. Verify thermostat heat pump settings are enabled (not AC-only mode)
2. Switch thermostat to cooling mode briefly, then back to heating
3. Listen for reversing valve "click" sound when switching modes
4. Check outdoor temperature - if below 25°F, use emergency heat temporarily
5. Inspect outdoor unit for ice buildup blocking coils
6. Turn off heat pump if outdoor unit is heavily iced
7. Allow 2-4 hours for complete defrosting of outdoor unit
8. Clear snow and debris from around outdoor unit
9. Replace air filter to ensure proper airflow
10. Test auxiliary heat by switching thermostat to emergency heat
11. If emergency heat works, reversing valve likely failed
12. Check that outdoor unit has adequate clearance (2 feet all sides)
13. Verify both circuit breakers are on for indoor and outdoor units
14. After defrost, switch back to normal heat and monitor
15. If still blowing cold, call professional for reversing valve diagnosis

When to Call a Professional

Don't attempt DIY repairs if you experience any of these situations:

• No click from reversing valve when switching modes
• Heat pump works perfectly in cooling but not heating
• Emergency heat works but normal heat doesn't
• Refrigerant lines show oil stains indicating leak
• Ice reforms on outdoor unit repeatedly after defrost
• Loud grinding or clicking from outdoor unit
• Heat pump older than 10 years with sudden heating failure
• Outdoor unit runs but feels cold to touch in heating mode
• Auxiliary heat never activates despite cold temperatures
• Recent refrigerant smell near outdoor unit

Prevention Tips

Stop this problem before it starts with these preventive measures:

• Schedule professional maintenance twice yearly (spring and fall)
• Keep outdoor unit elevated above snow level in winter
• Clear snow and ice from outdoor unit within 12 hours
• Replace air filters monthly during heating season
• Install programmable thermostat with heat pump-specific settings
• Test heating mode before cold weather arrives
• Ensure outdoor unit has 2-foot clearance from shrubs and structures
• Upgrade to cold climate heat pump if temperatures regularly drop below 15°F
• Install backup heat source for extreme cold events
• Monitor defrost cycles - should occur every 30-90 minutes in cold weather