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Marvair 8AA1024A-1060A & 8AA2036A-2060A I&O Manual
05/2023 Rev.3
Chapter 4 Start-Up
4.1 Check-Out of Cooling Cycle
Important: Be sure that the crankcase heater (if used) has been energized for at least 24 hours
before starting the unit(s). Double-check all electrical connections before applying power. Marvair
air conditioners with scroll compressors running on 3Ø power must be checked for proper rotation
during the initial start-up. Please refer to Section 2.8 for determining if the 3Ø compressors are
rotating correctly. Incorrect rotation can damage the compressor and is not covered by the warranty
Procedure
:
1. Set the cooling set point temperature on the wall thermostat to a point
higher
than the ambient
temperature. Set the heating set point temperature to a temperature that is
lower
than the ambient.
2. Set the thermostat system switch in the AUTO position. Nothing should operate at this time.
3. Set the time delay in the electrical control box to three minutes. Check the changeover setting of the
enthalpy or dry bulb sensor and reset it if needed (economizer-equipped models only). See Section
1.6.
4. Slowly lower the thermostat's cooling set point temperature until the switch closes. The indoor fan
should operate.
Once the indoor fan turns on, allow approximately three minutes for the compressor to start. Note that
the outdoor fan may not come on immediately, because it is cycled by refrigerant pressures.
NOTE: (Economizer-Equipped models only) To check the system operation under different ambient
conditions, the air temperature and enthalpy sensors must be "tricked". When outdoor ambient condi-
tions are higher than the control setting, a component cooler aerosol may be sprayed directly into the
enthalpy sensor to simulate low enthalpy conditions, causing the economizer damper to open.
Alternately, when outdoor conditions are lower than the set point, a source of heat such as a hair dryer
can be directed on the air temperature sensor to simulate warmer conditions, which will bring on
mechanical cooling and start the compressor.
5. To stop cooling, slowly raise the thermostat cooling set point to a temperature higher than the
ambient.
If the unit fails to operate, refer to the troubleshooting information in Chapter 4.
Follow the same procedure for additional units.
NOTE:
The fan purge allows the indoor fan to run for approximately 90 seconds after the compressor
is off. This operation provides a small improvement in system rated efficiency.
4.2 Check-Out of Heating Cycle
Procedure
: (Applies only to units with resistance elements)
1. Raise the heating set point temperature to a setting which is higher than the ambient temperature.
The fan and electric heat should immediately cycle on.
2. Move the system switch to the "OFF" position. All functions should stop.
NOTE:
(Economizer Equipped models only) The damper blade should remain closed during the
heating cycle (unless the minimum position potentiometer has been set for constant ventilation A fully
counterclockwise position corresponds to full closure of the damper.
