I
Red LED—Displays ON when fan is energized.
J
Red LED—Displays ON when first-stage cooling is
energized.
K
Red LED—Displays ON when second-stage cooling is
energized.
L
Red LED—Displays ON when reversing valve is ener-
gized.
M
Red LED—Displays ON when first-stage heat is
energized.
N
Red LED—Displays ON when second-stage heat
is energized.
O
J2 (Not Shown)—Cut for 50 hz operation. Lo-
cated under plastic housing approximately 1 in.
above comprotec override.
Table 2—Troubleshooting
LED CODES
ERROR DESCRIPTION
ACTION REQUIRED
Green flashes 1 time every sec and no
other LEDs are flashing.
Normal operation.
None.
Green flashes 1 time and Red flashes 1
time
Duct temperature sensor. First-stage heat
limit exceeded; heat will be locked out.
Wait until duct temperature cools below
exceeded temperature trip. (Heat leaving
air temperature trip limits set at LAT limits
POT on central control circuit board; range
is 110° to 175°F.)
Green flashes 1 time and Red flashes 2
times
Duct temperature sensor. Second-stage
heat limit exceeded.
Wait until duct temperature cools below
exceeded temperature trip. Range is 105°
to 155°F.
Green flashes 1 time and Red flashes 3
times
Duct temperature sensor. First-stage cool
limit exceeded; cool will be locked out.
Wait until duct temperature raises above
exceeded temperature trip (45°F).
Green flashes 1 time and Red flashes 4
times
Duct temperature sensor. Second-stage
cool limit exceeded.
Wait until duct temperature raises above
exceeded temperature trip (50°F).
Green flashes 1 time and Red flashes 5
times
HP temperature sensor. First-stage heat
limit exceeded; heat will be locked out.
Wait until HP temperature cools below ex-
ceeded temperature trip. Fixed at 110°F.
Green flashes 2 times and Red flashes 1
time
HP temperature sensor error. Second-
stage heat limit exceeded.
Wait until HP temperature cools below ex-
ceeded temperature trip. Fixed at 105°F.
Green flashes 2 times and Red flashes 2
times
HP temperature sensor. First-stage cool
limit exceeded; cool will be locked out.
Wait until duct temperature raises above
exceeded temperature trip (45°F).
Green flashes 2 times and Red flashes 3
times
HP temperature sensor. Second-stage cool
limit exceeded.
Wait until duct temperature raises above
exceeded temperature trip (50°F).
Green flashes 2 times and Red flashes 4
times
1. Duct temperature sensor.
2. Temperature sensor is shorted.
1. Verify that duct temperature sensor or
10k ohm resistor is attached to control cen-
ter at duct temperature connectors.
2. Replace duct temperature sensor.
Green flashes 2 times and Red flashes 5
times
1. Duct temperature sensor.
2. Temperature sensor is open.
1. Verify that duct temperature sensor or
10k ohm resistor is attached to control cen-
ter at duct temperature connectors.
2. Replace duct temperature sensor.
Green flashes 3 times and Red flashes 1
time
1. HP temperature sensor.
2. Temperature sensor is shorted.
1. Verify that HP temperature sensor or
10k ohm resistor is attached to control cen-
ter at HP temperature connectors.
2. Replace HP temperature sensor.
Green flashes 3 times and Red flashes 2
times
1. HP temperature sensor.
2. Temperature sensor is open.
1. Verify that HP temperature sensor or
10k ohm resistor is attached to control cen-
ter at HP temperature connectors.
2. Replace HP temperature sensor.
Green flashes 3 times and Red flashes 3
times
Damper fuse blown.
1. Check for short circuits on damper wire
connections at the dampers and control
center.
2. Replace damper fuse.
3. Check damper operation, may need to
be replaced.
Green flashes 3 times and Red flashes 4
times
Fatal control center circuit board failure.
Replace control center.
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