16
A05109v2
Fig. 16 -- Cooling Charging Chart
Airflow can be changed by changing the lead connections of the
blower motor.
All 704A units are factory wired for low speed, except sizes 030 and
048 which are wired for medium speed.
FOR 208/230v
For color coding on the 208/230v motor leads, see Table 4.
Table 4—
Color Coding for 208/230v Motor Leads
Black = High Speed
Blue = Medium Speed
Red = Low Speed
To change the speed of the indoor fan motor (IFM), remove the fan
motor speed leg lead from the time delay relay (TDR). This wire is
attached to terminal--3 of TDR for 3--phase units. To change the
speed, remove and replace with lead for desired blower motor speed.
Insulate the removed lead to avoid contact with chassis parts.
COOLING SEQUENCE OF OPERATION
With the room thermostat SYSTEM switch in the COOL position
and the FAN switch in the AUTO position, the cooling sequence of
operation is as follows:
When the room temperature rises to a point that is slightly above the
cooling control setting of the thermostat, the thermostat completes
the circuit between thermostat terminal R to terminals Y and G.
These completed circuits through the thermostat connect contactor
coil (C) (through unit wire Y) and time delay relay (TDR) (through
unit wire G) across the 24--v secondary of transformer (TRAN).
The normally open contacts of energized contactor (C) close and
complete the circuit through compressor motor (COMP) to
condenser (outdoor) fan motor (OFM). Both motors start instantly.
The set of normally open contacts of energized relay TDR close and
complete the circuit through evaporator blower (indoor) fan motor
(IFM).
NOTE
: Once the compressor has started and then has stopped, it
should not be started again until 5 minutes have elapsed.
The cooling cycle remains on until the room temperature drops to
a point that is slightly below the cooling control setting of the room
thermostat. At this point, the thermostat breaks the circuit between
thermostat terminal R to terminals Y and G. These open circuits
deenergize contactor coil C and relay coil TDR. The condenser and
compressor motors stop. After a 30--second delay, the blower motor
stops. The unit is in a standby condition, waiting for the next call for
cooling from the room thermostat.
MAINTENANCE
To ensure continuing high performance, and to minimize the
possibility of premature equipment failure, periodic maintenance
must be performed on this equipment. This cooling unit should be
inspected at least once each year by a qualified service person. To
troubleshoot unit, refer to Table 5, Troubleshooting Chart.
704A
