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Side Discharge Condensers
21
DFT TST R and DF2
DEFROST CONTROL BOARD
TESTING DEFROST OPERATION USING TEST PINS
SINGLE-ZONE AND DUAL-ZONE SEQUENCE OF OPERATION
WARNING!
Before removing the access panels to
the unit make sure that all power is dis-
connected from the unit. Failure to do so
could result in injurf or electric shock.
Defrost operation can be initiated us-
ing the test pins located on the circuit
board of the condensing unit. “Defrost test
operation” will be a time compressed ver-
sion of the actual defrost cycle.
With the system “off”, using two small
alligator clips, jumper the following sets of
test pins. “R and DF2” and “DFT TST”.
Defrost control board: Apply power
to the indoor and outdoor units. Place the
indoor unit in heating mode with the set
point temperature well above room tem-
perature. This is to ensure that the con-
denser will remain on during the entire
defrost test operation.
The condenser will operate in heat-
ing for approximately 20 seconds. At that
point the unit will enter defrost mode for
approximately 2 seconds. During this time
the condenser fan will switch off, the re-
versing valve will energize and the defrost
board will energize the indoor electric
heat relay through the “W” terminal. After
the two second defrost cycle is complete,
the unit will switch back to heating opera-
tion for another 20 seconds. This process
will repeat until the jumpers are removed
from the test pins.
Note: If the condenser coil is heavily
frosted up with ice, it is likely that the
“Defrost Sensor” is already closed. In
this case the “R and DFT” jumper can
be eliminated. To initiate defrost, mo-
mentarily jump pins marked “DFT TST”
until the defrost cycle begins. The unit
will remain in defrost mode until the
condenser coil is defrosted and then it
will return to heating mode. When test-
ing is complete be sure to remove the
jumper(s). DO NOT leave the unit in
test mode with jumper(s) in place.
Low ambient operation: If the unit
is equipped with low ambient fan control
for cooling, the fan will remain off (while in
cooling mode) until the condenser pres-
sure reaches 210psi. The fan will then en-
ergize and run until the condenser pres-
sure falls below 150psi. This will happen
only in the cooling mode (or when the re-
versing valve is energized). In heating (re-
versing valve not energized), the fan will
run continuous so long as the connection
is made between “R” and “Y”.