Air Handler
Frequently Asked Questions


  1. What is the purpose of the Suction loop to the top of the coil in a commercial air handler when the condensing unit is installed below the evaporator?

  2. Where do you connect the purple wire from the heat pump condensing unit since there is no purple wire on the air handler?

  3. I have just installed a HLA/HLL air handler with X-13 motor. The air handler does not move enough air and the motor seems to be running to slow.

  1. What is the purpose of the Suction loop to the top of the coil in a commercial air handler when the condensing unit is installed below the evaporator?


    • The suction loop as described in the installation instructions is to prevent the migration of refrigerant and oil to the compressor in the off cycle.
  1. Where do you connect the purple wire from the heat pump condensing unit since there is no purple wire on the air handler?


    • If supplemental heat is required during the defrost cycle of the heat pump condensing unit the purple wire should be connected to the "W" terminal of the thermostat.
  1. I have just installed a HLA/HLL air handler with X-13 motor. The air handler does not move enough air and the motor seems to be running to slow.


    • The HLA/HLL air handler uses the Green fan wire to energize the fan at 50% air volume in constant fan run operation (sub base selection to ON). The 24 Volt wiring requires that the Yellow wire from the thermostat be attached to the Yellow wire connection outside the air handler in order for the fan to deliver full volume air flow during a call for cooling or heating.

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