Air Conditioning Installation



If you're looking for someone to handle your air conditioning installation for you, our Find an Air Conditioning Contractor page has some tips you might find helpful.

If you're going to do an air conditioning installation yourself, and you're not sure about the materials and work involved in the procedure, maybe I can clear up the picture for you a little.


If there's an evaporator fan coil inside, and a condenser outside, it's a 'split' system.


Decide where you want your equipment installed.


You'll need to run refrigerant pipe and control wiring between the two units, and you'll need to run a condensate drain from the evaporator drain pan to a drain somewhere.

Measure the distance between the units, and buy enough refrigeration pipe, thermostat wire, electrical wire, conduit, fittings, pipe and conduit mounting hardware, and don't forget the thermostat.


If this is a new air conditioning installation, you may need to run "supply" power from your service panel to disconnects at the evaporator and condenser.


Measure the distance from the service panel to the unit locations, and buy the disconnects and enough conduit, mounting brackets, and wire, to reach.

Don't forget the "whip", which is the wire run from the disconnect to the unit.


Buy drain pipe and fittings.


If this is a central air conditioning installation, you'll need ductwork.

Don't guess about what size you need.

Have somebody who's competent size, make, and install your ductwork for you.


You'll need to mount both units securely.


For the outside unit, leave plenty of clearance for air flow.


For both units, allow access for future maintenance and repairs.


Want to save some money in the future?


When you shop for your equipment, ask to talk to a technician, and get his opinion on how much access to leave for future maintenance and repairs.


Making future service work easier will save technicians time, which will save you money.


OK, if you have your units and the materials you need, let's start this air conditioning installation.


First, verify that the capacities of the units match, and that they are rated for the power you are supplying.


Set the indoor unit in place and secure it, and run the drain line.


Set the condensing unit in place and secure it.


Install any ductwork required.


Mount the disconnects.


If you need to, drill the holes for the conduit and pipe runs.


Set the mounting brackets for the pipe and conduit in place


Install the piping, braze your connections, and leak test with nitrogen.


If the condensing unit is charged with refrigerant, leave the isolation valves closed, start the vacuum pump, then insulate the refrigerant piping and clamp it down.


If the condensing unit is charged with dry air, open the isolation valves to vent the air, start the vacuum pump, then insulate the refrigerant piping and clamp it down.


Install the conduit, pull the wire, then clamp the conduit down.


Make your electrical connections in the condenser, evaporator, service panel, disconnects and thermostat.


Check all electrical connections thoroughly.


Check to be sure the condenser and evaporator fans turn freely.


Check to be sure that the wiring connections at the compressor and compressor contactor are correct and tight.


After your vacuum has pulled down to 500 microns:


If your unit is charged with refrigerant, remove the vacuum gauge from the circuit, open the isolation valves, run the unit, and verify the charge is correct.


Add or remove refrigerant as necessary.


If your unit was charged with dry air, remove the vacuum gauge from the circuit, charge in refrigerant, run the unit, and continue charging in refrigerant to a full charge.


See our Charging Air Conditioning Systems page for tips on charging the unit,


And see our Air Conditioning System Commissioning and Startup page for tips on commissioning new units.


If your air conditioning installation is a ductless mini split,

The installation is the same except there will be no ductwork.


The thermostat wire will probably be run in the same cord as the power supply from the condenser to the evaporator,

And the drain line will probably go out the same hole as the refrigerant piping.


If this is a package air conditioning installation, you'll need to run supply duct from the unit into the building and to the rooms being cooled,

And return duct from the building back to the unit.


You'll need to install a thermostat in the building, and run wire from the thermostat out to the unit.


Decide where you want the thermostat, measure the distance from there out to the unit, and buy enough thermostat wire and conduit to reach.


The rest of the electrical installation will be the same as with the split unit.


You'll need to install a condensate drain line on the unit, and run it to an acceptable drain location.


Measure the drain fitting on the unit, and buy the fitting, pipe, elbows, trap, and mounting brackets or clamps.


Install the drain line and clamp it down.


When the electrical connections are done, double check them all thoroughly.


Check the compressor and compressor contactor connections to be sure they're correct and tight.


Be sure the condenser and evaporator fans turn freely.


Attatch your gauges and verify there is refrigerant in the unit.


Run the unit, and verify the charge is correct.


See our Charging Air Conditioning Systems page for tips on charging the unit,


And see our Air Conditioning System Commissioning and Startup page for tips on commissioning new units.


I hope this page has helped give you a clearer picture of what's involved in an air conditioning installation, and please, feel free to contact us with any specific HVAC questions you might have, including questions about air conditioning on Guam, or refrigeration on Guam.

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