Cleaning the heat pump heat exchanger and fan yourself — when and how (2026)

Updated: 2026-10-02 · ~2 min read

Status: October 2, 2026. Safety: disconnect the pump from power before any mechanical work.

Why a dirty outdoor coil raises bills

In an outdoor heat pump unit (ASHP/mono-split), air flows through the evaporator (outdoor coil, heating mode). Dust, pollen and leaves clog the fins:

• Condensing temperature rises → COP drops (typically a few percent up to over ten percent loss when dirty).
• The fan works against higher resistance → noisier operation, faster bearing wear.

Worst seasons: autumn (leaves) and summer (pollen, insects), but dust builds up year-round.

When to clean

• Visual inspection: once before the heating season and once mid-season (Oct/Mar).
• Blow-out/cleaning: when you can see clogged fins or hear increased fan noise.
• Full professional service: every 1–2 years (per manufacturer manual) — includes refrigerant circuit parameters.

How to do it safely (step by step)

1. Turn the pump off and wait a few minutes (refrigerant pressure in the circuit).
2. Remove coarse debris (leaves, twigs) with a soft brush or a low-pressure air blower.
3. Clean the fins from the air side with a soft fin comb, working along the fins — never bend the fins.
4. Do not use high pressure — it bends fins and worsens airflow.
5. Clean the fan blades and check the impeller spins freely (no debris blocking it).
6. Restart the pump; compare condensing/high-side temperatures from the logs/app against the pre-cleaning values — the difference confirms the improvement.

What NOT to do yourself

• Suspected refrigerant leaks (oily droplets, hissing, sudden efficiency drop) → F-gas certified technician.
• Evaporator (indoor side) cleaning — that is a technician job.
• Electrical work inside the cabinet — shock and damage risk.

Affiliate slot: service calendar / inspection contracts (CPA Money2Money) — annual reminder.

Sources