Troubleshooting guide
Heat pump runs constantly? Here is what is happening and what to do.
A heat pump that runs constantly is either undersized for the load, has lost refrigerant, has a dirty coil that's reducing efficiency, or is fighting a poorly insulated space. In Vermont, dirty coils are the most common fixable cause we encounter.
Likely causes, ranked by probability
- 1
Dirty coil reducing efficiency
System runs longer to reach setpoint.
Likelihood 35%
- 2
Low refrigerant
Reduced capacity means longer run times.
Likelihood 25%
- 3
Undersized system or poor insulation
System can't keep up with the load.
Likelihood 25%
- 4
Aggressive thermostat setpoint
Very low cooling or very high heating setpoints.
Likelihood 15%
What you can try first
- · Wash the filter
- · Rinse the outdoor coil
- · Raise heating setpoint or lower cooling setpoint by 2-3 degrees
When to call us: Cleaning and setpoint adjustments don't reduce runtime within a week.
When a cleaning helps, and when to call a repair pro
A good portion of “something is off” symptoms (musty smell, weak airflow, water dripping from the indoor unit, surface mold) trace back to a dirty blower wheel, clogged drain, or biofilm on the coil. A full disassembly cleaning solves those. If we get on site and find an electrical or mechanical fault (a failing capacitor, a stuck reversing valve, refrigerant issues), we will tell you and recommend a heat pump repair contractor. We do not do repairs ourselves.
Frequently asked questions
Is heat pump runs constantly dangerous?
Most causes of "heat pump runs constantly" are not immediately dangerous, but ignoring them can damage the system over time. Cleaning and setpoint adjustments don't reduce runtime within a week.
Can a cleaning fix this?
Sometimes. Biofilm, dirty coils, and clogged drain lines often resolve after a deep clean. Mechanical or electrical issues need a heat pump repair contractor instead.
Do you do repairs?
No. We focus on cleaning and twice-yearly maintenance. If your system needs a part replaced or an electrical fix, we will tell you what we see and recommend a repair contractor.
Try a cleaning first.
If the symptom traces back to a dirty unit, we can fix it. If it does not, we will tell you and point you to a repair pro.