34
ComPac 9/04-12
Note: The LL357D2 does not require the units to be in phase.
Procedure: (A/C Testing with LL357D2 Lead/Lag Control for Two Units)
1. Set the cooling temperature on the wall thermostat to a point higher than the ambient
temperature. Set the heating temperature to a temperature that is lower than the ambient
temperature. Turn the selector switch to the “off” position.
2. Set the time delay on unit No. 1 to “3” minutes, and No. 2 to “5” minutes.
3. Set the change over setting of the enthalpy control to the “d” setting (ComPac
®
II A/C only).
4. Provide power to A/C units and turn disconnects on.
5. Check incoming power to each unit. For units designed for operation on 208/230v, 60hz
power supply, the transformer is factory wired for a 230 power supply. For a 208 power
supply remove the orange lead from the transformer and connect the red lead. Insulate the
orange lead.
6. Cooling. Turn the selector switch on the thermostat to the “auto” position. Slowly lower
the cooling temperature until the switch closes. The indoor fan should operate on the lead
unit. Once the indoor fan turns on, allow approximately 3 to 5 minutes for the compressor
to start. Note that the outdoor fan may not come on immediately because it is cycled by
refrigerant pressures. Next, lower the temperature until the switch closes. Follow the
above procedures for the lag unit.
The green light on the lead lag control should be on. One amber light will be on to identify
the lead unit. The other light should be off. If the lag unit comes on with the lead unit the
light for the lag unit will not come on. You should never have all 3 lights on at one time.
Allow the units to run for 2 to 3 minutes then check the temperature differential between
the return air and the supply air with digital thermometer. The temperature differential
should be between 12 and 20 degrees depending on ambient temperature.
Next, slowly raise the cooling temperature until the switch opens. The compressor and
outdoor fan should turn off. The indoor fan will continue to run for “90” seconds until the
blower time delay relay (BTR) times out. Raise the temperature until the switch opens. The
lead unit will shut down accordingly to the same procedures as outlines above.
Note: (ComPac
®
II A/C only) To check the system operation under different ambient
conditions, the air temperature and enthalpy sensors must be “tricked”. When outdoor
ambient conditions are higher than the control setting, a component cooler aerosol may be
sprayed directly into the enthalpy sensor to stimulate 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 enthalpy sensor to simulate warm conditions, which
will bring on mechanical cooling and start the compressor.
7. Heating. Slowly raise the heating temperature until the switch closes. The fan and electrical
heat should immediately cycle on. The unit should start blowing warm air in 2 to 3 minutes.
Next, raise the temperature until the switch closes. Follow the above procedures for lag unit.
Hold the manual advance button in for nine seconds the lead lag lights should switch. Next,
slowly lower the temperature until the switches open. The lag unit should shut down
immediately. Next, slowly lower the temperature until the switch opens, the lead unit
should shut down immediately.
8. Replace thermostat cover and panels on the unit.
3.3 A/C T
ESTING
WITH
LL357D2
