Diagnostic guide
Heat pump error code? Here is what is happening and what to do.
Heat pump error codes vary by brand. Mitsubishi codes start with letters (P, E, U); Fujitsu codes are letter+number (E:00, A:01); Daikin uses two-character codes. The unit's blinking lights or display will show the code. Look it up in your owner's manual or call us with the code and we'll diagnose over the phone if we can.
Likely causes, ranked by probability
- 1
Communication error
Indoor-outdoor unit communication fault.
Likelihood 35%
- 2
Sensor failure
Temperature or pressure sensor returning invalid reading.
Likelihood 30%
- 3
Drain or condensate issue
Drain pan sensor triggered.
Likelihood 20%
- 4
Refrigerant pressure fault
High or low pressure switch tripped.
Likelihood 15%
What you can try first
- · Note the exact code and how often it blinks
- · Reset by turning off at breaker for 10 minutes
When to call us: Any error code that returns after a reset.
Our diagnostic process
We arrive within a one-hour window, inspect the system end-to-end, read any active error codes, test temperatures and pressures, and identify the actual cause. You get a written quote before any repair work starts. The $129 diagnostic fee is applied to any repair you proceed with.
Frequently asked questions
Is heat pump error code dangerous?
Most causes of "heat pump error code" are not immediately dangerous, but ignoring them can damage the system or raise repair cost. Any error code that returns after a reset.
Can a cleaning fix this?
Sometimes. Biofilm, dirty coils, and clogged drain lines often resolve after a deep clean. Mechanical or electrical issues require a diagnostic visit instead.
How much does diagnosis cost?
Our diagnostic visit is $129 flat, applied to any repair you proceed with. We will quote any repair before starting work.
Need a tech to take a look?
$129 flat diagnostic. Same-week scheduling across Vermont. Credited toward any repair.