TK 61555-2-MM-EN
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A technician must visually verify the damper will move.
Troubleshooting Defrost Damper
A problem with a damper will usually generate Alarm Code 29 or Alarm Code 30.
A
Alla
arrm
m C
Co
od
de
e 2
29
9 –– C
Ch
he
ecckk D
De
effrro
osstt D
Da
am
mp
pe
err C
Ciirrccu
uiitt
Alarm Code 29 indicates that the amp draw on the damper gear motor circuit was out of the
expected range.
1. Visually check the damper door to see that is not damaged and is attached to the damper
gear motor shaft.
2. Use the Interface Board Mode to see if the damper moves. Verify LED 31 Damper Door Open
and LED 32 Damper Door Close illuminate as required.
3. Check the continuity of the GMRED and GMBLK circuits from the J15 connector on the base
controller to damper gear motor.
4. Disconnect the damper gear motor harness from the main harness at the J16 connector near
the damper motor. Check the resistance of the damper gear motor between pins 1 and 2 in
connector on the damper gear motor harness. The resistance should be 4 to 5 ohms. If the
resistance is out of this range, check the continuity of the wires from the connector to the
damper gear motor. If these wires have good continuity, the damper gear motor is probably
defective.
A
Alla
arrm
m C
Co
od
de
e 3
30
0 –– D
De
effrro
osstt D
Da
am
mp
pe
err S
Sttu
ucckk
1. Visually check the damper door to see that is not damaged, stuck, or frozen in place.
2. Use the Interface Board Mode to see if the damper moves. Verify LED 31 Damper Door Open
and LED 32 Damper Door Close illuminate as required.
3. Check the continuity of the GMRED and GMBLK circuits for a short to ground.
4. Disconnect the damper gear motor harness from the main harness at the J16 connector near
the damper motor. Check the resistance of the damper gear motor between pins 1 and 2 in
connector on the damper gear motor harness. The resistance should be 4 to 5 ohms. If the
resistance is out of this range, check the continuity of the wires from the connector to the
damper gear motor. If these wires have good continuity, the damper gear motor is probably
defective.
Replacing Damper Gear Motor
1. Remove the evaporator access panels as necessary to access the damper gear motor and
damper door.
2. Remove the two bolts that attach the damper door to the damper door shaft.
Figure 101.
Removing Damper Door and Gear Motor
