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How to Install a New HVAC Condenser Unit

Elizabeth Knoll

HVAC condenser units allow people to be comfortable in their homes. Using refrigerant, they pull the heat and humidity out of the air and return nice, dry, and cool air. Most of the time it is best to have a professional heating and air conditioning technician install a new HVAC condenser unit.

You need a special refrigerant certification to handle and install the refrigerant that goes into condenser units. If you have this certification, however, you can install an HVAC condenser unit yourself.

  1. Select an appropriate location for your HVAC condenser unit. Look for a spot that is strong enough to support the unit and allows the unit to be serviced easily. Level the unit and place on treated lumber or steel framing. Anchor the unit down to prevent the unit from shifting during operation.

  2. Inspect the unit and ensure no components have come loose during shipment. Check all bolts, electrical connections, etc.

  3. Properly size all copper tubing using a line chart. Install and braze the copper tubing for the liquid and suction lines. When brazing, flow an inert gas like nitrogen through the lines to prevent scale and oxidation in the lines. The copper tubing will hook up from the condensing unit outside to the evaporator coil on the indoor unit. Secure and support all lines with copper pipe straps. The smaller the pipe, the more straps you will need.

  4. Leak-check the unit by opening all service valves and pressuring the unit to 150 PSI with dry nitrogen. Let the unit sit for several hours. If you notice the pressure has dropped, leak-test all connections and joints with soap bubbles.

  5. Insulate all copper tubing with Armaflex pipe insulation (see Reference 2). If lines are not insulated, this will cause possible unit malfunction and sweating of the copper lines. This insulation cuts very easily with a utility knife and self-adheres together.

  6. Release the nitrogen pressure out of the lines and start evacuating the lines. This is done by hooking the refrigerant gauges up to the high and low side and starting the vacuum pump. This removes all contaminants out of the lines by essentially pulling all air and moisture out.

  7. Wire the unit up to the electrical panel by consulting the individual unit's wiring diagram and local electrical codes.

  8. Charge with refrigerant. Different units use different types of refrigerant, so ensure you are using the right type by consulting the installation manual that came with your unit. Each installation manual will have a chart with how much refrigerant to put in, which depends on unit size and length of copper tubing.

  9. Hook up refrigerant gauges and amperage meter. Set the room thermostat to the desired setting and turn the power on to the unit. Observe high and low side pressures as well as temperatures. Verify these are in the operational range as determined by the installation manual. If not, add or remove refrigerant as necessary to achieve the correct readings.

  10. Tip

    Most units need the outside temperature to be over 55 degrees Fahrenheit to properly charge the unit with the correct amount of refrigerant. Keep twists and bends of copper tubing to a minimum to ensure the best possible efficiency of the condensing unit.


    Refrigerant certifications are crucial to install condensing units and charge them with refrigerant. Without this certification, you are subject to hefty fines if caught using refrigerant.