How to Install a Heat Pump Compressor

What You'll Need
Container for capture of refrigerant
Wire Cutters
Professional vacuum
Safety equipment

Your heat pump compressor has malfunctioned, and now needs to be replaced. Replacing the part yourself can save you thousands over a whole system replacement or a contractor repair visit. 

Step 1 - Double Check the Compressor

Be certain that the compressor needs replacement before beginning this job. Then think seriously about whether you want to take on the task or call in a professional. Refrigerant is hazardous to work with, and has to be disposed of properly. Only begin this DIY project if you are certain that you have the knowledge and tools to complete the job safely.

Step 2 - Determine Replacement Type

Look at the old compressor's manufacturer, model, and capacity. Use this information to find a replacement that is compatible with your heat pump. The capacity must match exactly, or you risk either blowing out your compressor if it's too small, or wasting power if it's too large.

Step 3 - Shut Down the Heat Pump

Go to the breaker box and turn off the power to your heat pump. Make sure there is no power to the heat pump before beginning your compressor installation.

Step 4 - Remove Refrigerant

Remove all of the refrigerant from the system. This is a project in and of itself. The old refrigerant must be disposed of according to EPA regulations, incorrect disposal methods are a danger not only to wildlife but to humans, especially the person doing the disposal. The replacement refrigerant will have to be a currently approved type; many older heat compressors used obsolete refrigerants, mainly R11 and R22. The new compressor will not be designed to work with these refrigerants. The system may require modifications to the valves, coils, or other materials in order to accommodate the new refrigerant.

Step 5 - Remove the Old Compressor

Once the refrigerant has been completely removed, you may cut the refrigerant lines and then remove the compressor. The compressor should be easily removed with careful use of a screwdriver to undo the assembly bolts.

Step 6 - Install the New Compressor

Place the new compressor in the brackets left by the old one. Connect the refrigerant lines to the cut ends of the old refrigerant lines by soldering them together. If any other coils or controls need to be cut out and replaced, do so now.

Step 7 - Vacuum Check the System

Using a purpose-designed vacuum, draw all air out of the refrigerant lines and the new compressor. This is done to check for any leaks that may have been caused by the installation process. If air does get into the lines and stay there, it will mix with the refrigerant and prevent it from working properly. Moisture must also be kept out of the lines, or it will erode and eventually disable the system.

Step 8 - Add Refrigerant and Check Install

Add refrigerant to the system. Make sure to use the proper charge amount. If the system is overcharged or undercharged, it will malfunction. Once you have finished this installation process, turn the power back on at the breaker box, and test your heat pump for proper functionality by turning it on and seeing that it heats and cools properly.