Heat Pump Troubleshooter

Use this interactive heat pump troubleshooting tool to sort common symptoms into three categories: normal behavior, safe homeowner checks, and problems that should be inspected by an HVAC professional. It does not replace diagnosis by a technician.

Safety first: If you see smoke, active sparking, signs of fire, smell gas, or a carbon monoxide alarm is sounding, leave the area as appropriate and contact emergency services or the gas utility from a safe location. Do not use this tool to troubleshoot a life-safety emergency.

Safe Heat Pump Checks Homeowners Can Make

ENERGY STAR recommends basic homeowner maintenance such as checking filters regularly and keeping indoor and outdoor equipment clear of dust, snow, leaves, and other debris. For ductless systems, ENERGY STAR also recommends using HEAT or COOL rather than AUTO mode and keeping filters clean.

• Confirm the thermostat is in the intended HEAT or COOL mode.
• Use a steady thermostat setpoint rather than large temperature swings.
• Check and clean or replace a dirty filter according to manufacturer instructions.
• Make sure supply and return registers are open and unobstructed.
• Keep the outdoor unit clear of loose snow, leaves, and debris.
• Read thermostat error messages and consult the equipment or thermostat manual.

What Not to Troubleshoot Yourself

• Refrigerant charge, leaks, or refrigerant-line repairs
• Compressor, capacitor, contactor, or internal electrical testing
• Opening energized electrical compartments
• Bypassing safety switches or controls
• Repeatedly resetting a breaker that trips
• Chipping or striking ice from an outdoor coil
• Fuel-burning furnace or gas-system repairs without appropriate training

CPSC specifically advises consumers not to service fuel-burning appliances without proper knowledge, skill, and tools. A sounding carbon monoxide alarm should never be treated as an HVAC troubleshooting exercise: move outside to fresh air and contact emergency services.

Why Is AUX Heat On?

Auxiliary heat is backup heat that can supplement a heat pump. Depending on the system, it may operate during very cold weather, recovery from a large thermostat change, or certain defrost conditions. Seeing AUX occasionally does not automatically mean the heat pump is broken.

If auxiliary heat operates almost continuously under ordinary conditions, the system may deserve a closer look. Possible factors include high building load, thermostat strategy, sizing, airflow, backup-heat controls, or reduced heat-pump performance.

What Is Emergency Heat?

On many heat-pump thermostats, Emergency Heat is a manually selected backup-heating mode that reduces or disables normal heat-pump operation and relies on the backup heat source. Exact behavior varies by thermostat and system, so check the manufacturer’s instructions before changing modes.

Is Frost on a Heat Pump Normal?

Light frost on an outdoor coil can occur in heating mode during cold, humid weather. Heat pumps use a defrost cycle to melt that frost, which can also produce water around the outdoor unit. ENERGY STAR notes that outdoor units release water during winter defrost and recommends considering drainage and icing when locating equipment.

Heavy ice that does not clear, blocks airflow, or encases the unit is different and should be inspected.

When Heat Pump Problems Are Urgent

Stop ordinary troubleshooting if there is smoke, fire, active sparking, a strong burning smell, a gas odor, or a carbon monoxide alarm. CPSC says a sounding CO alarm should not be ignored: move outside to fresh air and call emergency services.

Loss of heat during dangerous winter conditions can also become a household safety problem even when the HVAC fault itself is not a fire or gas emergency. Arrange service promptly and use only safe, manufacturer-approved backup heating methods.

Heat Pump Troubleshooting FAQs

Why is my heat pump not heating?

Start by confirming HEAT mode, thermostat setpoint, filter condition, airflow, and outdoor-unit clearance. If those are normal but the home still cannot maintain temperature, professional diagnosis is appropriate.

Why is my heat pump blowing cool air?

Heat-pump supply air can feel cooler than furnace air while still heating the home normally. If indoor temperature continues to reach setpoint, that may be normal. If the home is getting colder, request diagnosis.

Why does my heat pump run all the time?

Variable-capacity heat pumps can run for long periods at lower output. Continuous operation becomes more concerning when the system cannot maintain setpoint, energy use changes sharply, or comfort declines.

Should I reset a tripped heat pump breaker?

Do not repeatedly reset a breaker that trips. A trip can indicate an equipment or electrical fault that should be diagnosed.

Related Heat Pump Troubleshooting Guides

• Heat Pump Not Heating
• Heat Pump Not Cooling
• Heat Pump Blowing Cold Air
• Heat Pump Frozen in Winter & Defrost
• What Is Auxiliary Heat?
• Emergency Heat on a Heat Pump

Methodology & Safety Sources

The troubleshooting paths are intentionally conservative. They are limited to low-risk homeowner checks such as thermostat settings, filters, airflow, and outdoor-unit clearance. They do not attempt to diagnose refrigerant, internal electrical, gas, or combustion faults.

• ENERGY STAR: Air-Source Heat Pumps
• ENERGY STAR: Ductless Heating & Cooling
• ENERGY STAR: HVAC maintenance and filter guidance
• U.S. CPSC: Carbon Monoxide Fact Sheet

Need Heat Pump Repair in Eldora, IA?

If the troubleshooter points to professional service, send the symptom, thermostat status, equipment type, approximate system age, and your location. Your request can then be matched with an HVAC professional serving Eldora or the surrounding area, subject to availability.