What does 'Aux Heat' mean on my heat pump thermostat?

Aux Heat (auxiliary heat) activates when the heat pump cannot extract sufficient heat from the outdoor air to meet your thermostat setting. This is normal when it is extremely cold outside. However, if Aux Heat is running constantly in mild weather (above 40°F), your heat pump is underperforming and needs a diagnostic inspection.

Heat Pump Repair in Pittsburgh, PA — 24/7 Emergency Service

Q: Why is my heat pump iced over?

A heat pump icing over is usually caused by a faulty defrost control board or defrost sensor, a refrigerant leak causing the coil to drop too cold, or a failed outdoor fan motor. All of these require professional repair to prevent compressor damage.

Q: How much does heat pump repair cost in Pittsburgh?

Our diagnostic fee is $89, which covers a full system inspection and a flat-rate repair quote. Common repairs range from $150 to $600 for capacitors and contactors, $800 to $1,500 for reversing valve replacement, and vary for refrigerant leaks depending on the location and severity.

Blowing cold air in winter? Iced over? Won't start? Our NATE-certified technicians diagnose and fix all heat pump problems — reversing valves, defrost boards, refrigerant leaks, and more. Flat-rate pricing, 24/7 dispatch across Allegheny County.

HEATING SERVICES SCHEDULE AC SERVICE

Heat pump emergency? We dispatch technicians 24/7 — including weekends and holidays.

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COMMON PROBLEMS

What's Wrong With Your Heat Pump?

Heat pumps have unique failure modes that differ from standard AC units. Here are the most common issues we repair daily across Pittsburgh.

MOST COMMON

Reversing Valve Failure

Symptom: Blows hot air in summer or cold air in winter

The reversing valve is what makes a heat pump unique — it switches the refrigerant flow between heating and cooling modes. When it sticks or fails, your system gets permanently locked in one mode. Replacement is involved but straightforward for a trained technician.

WINTER ISSUE

Defrost Board / Sensor Failure

Symptom: Outdoor unit completely encased in ice

Heat pumps normally form a light frost on the outdoor coil in winter. A defrost cycle should automatically melt it every 30-90 minutes. If the control board or sensor fails, the defrost never runs and the coil becomes a solid block of ice, destroying efficiency.

EFFICIENCY KILLER

Refrigerant Leak

Symptom: Weak heating/cooling, system runs constantly

Heat pumps use refrigerant to transfer heat. A slow leak causes the system to lose capacity, run longer, and eventually freeze the coil. We locate the leak using nitrogen pressure testing, repair it at the source, pull a deep vacuum, and recharge with the correct refrigerant.

QUICK FIX

Capacitor / Contactor Failure

Symptom: Heat pump won't start, hums but no fan

Capacitors store electrical energy to start the compressor and fan motors. Contactors are the heavy-duty electrical switches. Both wear out every 5-10 years and are among the most common heat pump repairs. Usually same-day with parts on our trucks.

EFFICIENCY ALERT

Auxiliary Heat Running Constantly

Symptom: Thermostat shows Aux Heat even in mild weather

Auxiliary heat strips are expensive to run. If they activate constantly above 40°F outdoor temperature, your heat pump has lost capacity due to a refrigerant leak, dirty coils, or a failing compressor. Ignoring it can double your electricity bill.

MAJOR REPAIR

Compressor Failure

Symptom: Heat pump makes loud noise, no heating or cooling

The compressor is the heart of the heat pump. Failure is usually caused by years of operating with low refrigerant or dirty coils. We will diagnose whether compressor replacement makes financial sense vs. investing in a full new system with available tax credits.

OUR PROCESS

How We Diagnose Your Heat Pump

Unlike general HVAC technicians, our team is specifically trained on heat pump technology — including refrigerant circuit analysis, defrost logic, and reversing valve testing.

SCHEDULE DIAGNOSIS — $89

System-Wide Electrical Check

→Test all capacitors with a digital capacitor meter
→Check contactor for pitting and proper amp draw
→Verify transformer output and control board voltages
→Inspect all low-voltage wiring for corrosion
→Pull error codes from thermostat and board

Refrigerant & Mechanical Check

→Measure suction and discharge pressures digitally
→Calculate superheat and subcooling for proper charge
→Test reversing valve solenoid in both modes
→Check defrost board and sensor resistance values
→Inspect coils for ice, dirt, and refrigerant oil staining

2026 REPAIR PRICING

Heat Pump Repair Costs in Pittsburgh

Flat-rate pricing. You approve the quote before we turn a wrench. $89 diagnostic fee applied toward any repair over $250.

WHY CHOOSE US

Pittsburgh's Heat Pump Repair Specialists

Heat Pump Specialists

We are not general HVAC techs moonlighting on heat pumps. Our technicians are specifically trained on reversing valve logic, defrost cycle diagnostics, and refrigerant circuit analysis unique to heat pumps.

$89 Flat-Rate Diagnostic

One fee covers a full electrical, refrigerant, and mechanical inspection. You get a complete written repair quote before we start. No surprises. The $89 is applied toward any repair over $250.

Fully Stocked Repair Trucks

We carry capacitors, contactors, defrost boards, and common reversing valves for major brands on every truck — enabling same-day repairs on most heat pump issues.

1-Year Repair Warranty

All heat pump repairs come with a 12-month parts and labor warranty. If the same issue returns, we fix it at no charge. That is our guarantee.

Heat pump repair technician Pittsburgh PA

1-412-388-9408

acpittsburghpa@gmail.com

FAQ

Heat Pump Repair Questions

Why is my heat pump blowing cold air in the winter?

If your heat pump blows cold air in winter, the most likely causes are: (1) the reversing valve is stuck in cooling mode and needs replacement, (2) the system is low on refrigerant due to a slow leak, or (3) it is in a normal defrost cycle (should last under 10 minutes). If it blows cold consistently, call for a diagnostic.

Why is my heat pump iced over?

A heat pump forming a solid block of ice is caused by a faulty defrost control board or temperature sensor, a refrigerant leak causing the coil to drop below freezing, or a failed outdoor fan motor. Turn the system off immediately and call us — running it iced over will destroy the compressor.

What does it mean when my thermostat says Aux Heat?

Aux Heat activates when the heat pump alone cannot meet the heating demand. This is normal when outdoor temps are below 35°F. However, if Aux Heat runs constantly during mild weather (above 40°F), your heat pump has lost capacity and needs a refrigerant check or full diagnostic.

How much does heat pump repair cost in Pittsburgh?

Our diagnostic fee is $89 and covers a complete system inspection. Common repairs: capacitor $150–$300, contactor $150–$250, defrost board $350–$750, reversing valve $800–$1,500. The $89 diagnostic fee is credited toward any repair over $250.

Should I repair or replace my heat pump?

A good rule of thumb: if the repair cost exceeds 50% of the value of a new system, replacement is usually smarter — especially since high-efficiency heat pumps now qualify for a $2,000 federal tax credit. We will always give you an honest assessment before recommending replacement.

How long does a heat pump repair take?

Most common repairs (capacitor, contactor, defrost board) are completed same-day in 1–3 hours. Reversing valve replacement typically takes 3–5 hours. Refrigerant leak repairs vary depending on the location of the leak.

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Heat Pump Repair Across Allegheny County

Same-day and emergency heat pump repair for homes across Greater Pittsburgh.

📍 Pittsburgh

📍 Mt. Lebanon

📍 Bethel Park

📍 Canonsburg

📍 Monroeville

📍 Penn Hills

📍 Allison Park

📍 Carnegie

📍 Bridgeville

📍 North Hills

📍 Moon Township

📍 Cranberry Township

📍 Coraopolis

📍 Shadyside

📍 Squirrel Hill

📍 West Mifflin

Heat Pump Not Working? Call Now.

Our dispatch team is standing by 24/7. We'll have a heat pump specialist at your door today.

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