How to Fix a Coil in a Heat Pump

A heat pump is a device that moves thermal energy from a cool environment (typically outside) to a warm environment (typically inside a building) using compression and expansion. Heat pumps are commonly found in warm climates to heat homes during the winter months. These heat pumps have two heat exchanger coils: one in the ventilation system and one outside. Either coil can become damaged by cracking the tubing, creating a leak of the refrigerant, or through normal usage and fouling of the inside of the tubes.

Fouled coil
Open-end wrenches
Safety goggles and gloves
Solvent
Steel bucket
Air compressor with hose

Instructions

- 1
  Depressurize the heat pump system. The exact process for depressurizing the refrigerant coil will vary depending on heat pumps, but it generally involves connecting an empty refrigerant bottle to the filling port then opening the port and briefly running the compressor.
- 2
  Disconnect the heat exchanger from the heat pump system. The open end wrenches are useful for loosening the nuts on the tubing connectors. Pull the tubes to the side so that you get some room to work around the heat exchanger. If it is the smaller heat exchanger in the house, you should fully remove it and take it outside to clean it out.
- 3
  Put on safety goggles and gloves.
- 4
  Fill the coil with solvent through the output. Leaks will indicate you need to replace the coil. By filling it through the output, you will initially wash out loose particles caught inside the tubing.
- 5
  Shake the heat exchanger back and forth gently every ten minutes or so for an hour to break up the fouling within the tubing.
- 6
  Hold the input of the coil over the steel bucket, then hook the air compressor hose up to the output. Turn on the air compressor and use high pressure air to force the solvent from the coil. The solvent will come out brownish black and may contain small particles.
- 7
  Repeat washing the inside of the coils with fresh solvent until the solvent comes out clean, then run plain air through the coils for 10 minutes to fully remove any residue solvent.
- 8
  Connect the heat exchanger back to the heat pump lines, then fill the heat pump with new refrigerant. The old refrigerant is already broken down and will quickly foul the coil again if reused.

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