122
TK 61555-2-MM-EN
Figure 100.
Evaporator Blower Housing
1.
Damper Stop
3.
Damper Gear Motor
2.
Damper Door (Open)
4.
Scroll Panel
The unit is equipped with a base controller that contains a a damper gear motor drive to control
the damper gear motor. The base controller used in trailer units without the damper gear motor
will not work with the damper gear motor. Make sure to order the correct base controller if it is
being replaced.
The defrost damper is open when the unit is in Cool or Heat, and closes when the unit is in
Defrost. To close, the damper gear motor moves the damper door down until it contacts the top
of the scroll panel. To open, the damper gear motor moves the damper door up until it contacts
the damper stops.
Alarm Code 29 – Check Defrost Damper Circuit and Alarm Code 30 – Defrost Damper Stuck are
associated with the defrost damper.
•
Alarm Code 29 is set during the Pretrip Test if the controller senses a fault in the damper gear
motor operation.
•
Alarm Code 30 is set any time the controller tries to move the damper and the damper gear
motor draws excessive current for a specified time.
In some conditions, such as when the unit is turned off, the damper is left in the last position to
minimize operation and wear on the damper gear motor.
Testing Defrost Damper
The damper operation can be tested as part of the Pretrip Test, or by using the Interface Board
Test Mode.
P
Prre
ettrriip
p T
Te
esstt
•
Closes then opens the damper
•
Checks amp draw while damper moving
•
Alarm Code 29 is recorded if the damper fails the test.
IIn
ntte
errffa
acce
e B
Bo
oa
arrd
d T
Te
esstt M
Mo
od
de
e
•
This test is used to verify the damper will move.
•
LED 31 Damper Door Open and LED 32 Damper Door Close illuminate as required.
•
The initial (breakaway) current draw occurs over a very short period of time and cannot be
accurately measured. Once the motor is running, the current draw should not exceed 0.8
amps.
