1. Thermostat mode or staging issue
Symptoms: System runs without meaningful heat output.
DIY check: Set thermostat to Heat and raise setpoint several degrees.
Professional fix: Verify thermostat programming, staging calls, and control wiring.
Heat Pump No-Heat HelpSame-day service available
Heat Pump Not Heating? Fast Repair in Phenix City
If your heat pump is running but not warming the house, the issue may involve defrost controls, refrigerant, reversing valve operation, airflow, or backup heat staging.
Underwood Heating & Air Conditioning provides same-day heat pump diagnostics across Phenix City, Auburn, Opelika, and East Alabama with emergency no-heat support when needed.
- •Upfront pricing
- •Licensed & insured
- •Fast local response
Heat pump no-heat symptoms can look similar but require different repairs. Safe checks can help, but recurring no-heat or icing should be diagnosed quickly to avoid comfort loss and energy waste.
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Licensed & InsuredServing Phenix City & East Alabama24/7 Emergency Service
See our Google reviews8 common reasons this HVAC problem happens
2. Low refrigerant due to leak
Symptoms: Weak heat delivery, long runtimes, and possible icing outdoors.
DIY check: Check for persistent frost/ice and reduced indoor temperature gain.
Professional fix: Locate and repair leak source, then recharge to manufacturer spec.
3. Defrost control failure
Symptoms: Outdoor unit ices and heating output drops sharply.
DIY check: Observe whether outdoor coil remains iced for long periods.
Professional fix: Test defrost board/sensors and restore proper defrost cycles.
4. Auxiliary heat not engaging
Symptoms: Indoor temperature stalls during colder weather conditions.
DIY check: Check if AUX/EM heat indicator appears during high demand.
Professional fix: Test heat strips, relays, breakers, and staging logic.
5. Reversing valve fault
Symptoms: System may stay in cooling mode behavior or deliver cool air in heat mode.
DIY check: Note whether supply air feels cool despite clear heat call.
Professional fix: Diagnose reversing valve control/operation and correct mode-switch issues.
6. Airflow restriction
Symptoms: Low vent airflow and poor room-to-room heating consistency.
DIY check: Replace filter and ensure major returns/supplies remain open.
Professional fix: Measure airflow/static pressure and correct blower/duct restrictions.
7. Outdoor fan or compressor performance issue
Symptoms: Unit runs inefficiently, may short cycle, and fails to maintain heat.
DIY check: Listen for abnormal startup sounds or repeated cycling.
Professional fix: Complete electrical/mechanical diagnostics and repair failed components.
8. Control board or sensor faults
Symptoms: Erratic operation with inconsistent heat output and system response.
DIY check: Track patterns in run behavior and thermostat responses.
Professional fix: Test control logic/sensors and restore consistent operating sequence.
Quick troubleshooting flow (before you call)
Step 1: Is thermostat definitely set to Heat and above room temperature?
If yes: Go to Step 2.
If no: Correct settings and monitor for startup response.
Step 2: Is airflow restricted by dirty filter or blocked vents?
If yes: Replace filter/open vents and recheck heat output.
If no: Go to Step 3.
Step 3: Is outdoor coil heavily iced?
If yes: Call for defrost/no-heat diagnosis.
If no: Go to Step 4.
Step 4: Does AUX/EM heat engage during demand spikes?
If yes: Go to Step 5.
If no: Schedule same-day backup-heat diagnostics.
Step 5: Still not heating after checks?
If yes: Request full heat pump diagnostic and repair options.
If no: Schedule preventive service to avoid repeat no-heat events.
DIY checks you can do safely
Verify thermostat heating demand
Confirm Heat mode and appropriate setpoint above room temperature.
Replace filter if dirty
Airflow restriction can reduce heating performance significantly.
Check outdoor coil condition
Persistent heavy ice suggests defrost or refrigerant problems.
Monitor AUX/EM heat behavior
Backup heat should engage during colder conditions and high demand.
Listen for unusual unit sounds
Hard-start or repeated cycling patterns are useful diagnostic clues.
When to call a professional immediately
- !Complete no-heat during cold nights
- !Breaker trips or electrical smell
- !Severe icing with indoor heat loss
- !Vulnerable occupants in rapidly cooling home
- !Loud mechanical noise with failing startup
What to expect from our diagnosis process
- 1. Thermostat and staging verification
- 2. Defrost, refrigerant, and reversing valve diagnostics
- 3. Auxiliary heat and electrical testing
- 4. Airflow and system capacity checks
- 5. Upfront repair options before work starts
- 6. Post-repair heating verification across zones
Pricing transparency and next steps
Heat pump no-heat issues vary from controls and airflow to refrigerant and major component repairs.
We provide straightforward options after diagnosis confirms the root cause.
All repairs are approved by you before work begins.
Serving Phenix City, Auburn, Opelika & East Alabama
Same-day heat pump no-heat service is available in Phenix City, Auburn, Opelika, and nearby East Alabama service areas.
Frequently Asked Questions
Heat Pump Not Heating? Fast Repair in Phenix City FAQ
Why is my heat pump running but not heating?
Common causes include defrost issues, low refrigerant, reversing valve faults, airflow restrictions, or backup heat problems.
Should a heat pump blow hot air like a furnace?
Heat pump supply air usually feels warm, not as hot as furnace air, but it should still raise room temperature consistently.
What does it mean if AUX heat never comes on?
Backup heat staging may be failing, especially during colder weather when demand is high.
Is outdoor icing normal in heating mode?
Light frost can be normal, but heavy persistent ice indicates a defrost or refrigerant issue.
Can a dirty filter make a heat pump stop heating well?
Yes. Restricted airflow lowers system performance and can trigger additional operating issues.
Do you provide same-day heat pump repair in Auburn?
Yes. Same-day service is common in Auburn and surrounding areas.
Do you service variable-speed and standard heat pumps?
Yes. We diagnose and repair single-stage, two-stage, and variable-speed heat pump systems.
When should I call emergency heating service?
Call immediately for complete no-heat outages, electrical smells, repeated breaker trips, or severe icing with comfort loss.
Will you explain repair versus replacement choices?
Yes. We compare system condition, age, and projected value before you decide.
Do you provide upfront pricing after diagnosis?
Yes. We provide clear repair options before any work is performed.
Need help now?
24/7 emergency support and same-day diagnostics.
Call for fast local help. We diagnose first, explain your options clearly, and restore comfort as quickly as possible.
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We’re ready when you are.
Request service online or call now. We’ll follow up quickly to confirm details and scheduling.
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