Carrier 48TF004-007 Installation, Start-Up And Service Instructions Manual Download Page 52

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6. Remove the jumper from the Air Change terminals.

Jumper the Shutdown terminals. The exhaust LED turns
off. The Unit Control, Indoor Fan, and Exhaust Fan con-
tacts open. The actuator drives fully closed.

7. Remove the jumper from the Shutdown terminals. Jump-

er the Purge terminals. The exhaust LED turns off. The
Unit Control and Indoor Fan contacts open. The Exhaust
Fan contacts close. The actuator drives fully closed.

8. Return EconoMi$er2 settings and wiring to normal after

completing troubleshooting.

MIXED AIR INPUT — To check mixed air input:

1. Make sure EconoMi$er2 checkout procedure has been

performed.

2. Set the Enthalpy potentiometer to A. The Free Cool LED

turns on.

3. Replace the 6.8 Kohm resistor across T and T1 with a

5.6 Kohm resistor. The actuator should drive 20 to 80%
open.

4. Remove the 5.6 Kohm resistor and jumper T to T1. The

actuator should drive fully open.

5. Remove the jumper across T and T1. The actuator should

drive fully closed.

6. Replace the 6.8 Kohm resistor across T and T1. The actu-

ator should remain fully closed.

7. Return EconoMi$er2 settings and wiring to normal after

completing troubleshooting.

MIXED-AIR SENSOR — The mixed-air sensor has a nega-
tive coefficient. As the ambient temperature increases, the
resistance decreases. The sensor changes 70 ohms for every
1 degree change in temperature. See Fig. 53 for a resistance vs.
temperature chart which can be used to check sensor calibra-
tion and operation.

Table 32 — LED Error Code Service Analysis

LEGEND

PROBLEM

CAUSE

REMEDY

Hardware failure.
(LED OFF)

Loss of power to control module (IGC).

Check 5 amp fuse on IGC, power to unit, 24-v circuit breaker,
and transformer. Units without a 24-v circuit breaker have an
internal overload in the 24-v transformer. If the overload trips,
allow 10 minutes for automatic reset.

Limit switch fault.
(LED 2 flashes)

High temperature limit switch is open.

Check the operation of the indoor (evaporator) fan motor.
Ensure that the supply-air temperature rise is in accordance
with the range on the unit nameplate.

Flame sense fault.
(LED 3 flashes)

The IGC sensed flame that should not be
present.

Reset unit. If problem persists, replace control board.

4 consecutive limit
switch trips.
(LED 4 flashes)

Inadequate airflow to unit.

Check operation of indoor (evaporator) fan motor and that
supply-air temperature rise agrees with range on unit name-
plate information.

Ignition lockout.
(LED 5 flashes)

Unit unsuccessfully attempted ignition for
15 minutes.

Check ignitor and flame sensor electrode spacing, gaps, etc.
Ensure that flame sense and ignition wires are properly termi-
nated. Verify that unit is obtaining proper amount of gas.

Induced-draft motor fault.
(LED 6 flashes)

IGC does not sense that induced-draft motor is
operating.

Check for proper voltage. If motor is operating, check the speed
sensor plug/IGC Terminal J2 connection. Proper connection:
PIN 1 — White, PIN 2 — Red, PIN 3 — Black.

Rollout switch fault.
(LED 7 flashes)

Rollout switch has opened.

Rollout switch will automatically reset, but IGC will continue to
lock out unit. Check gas valve operation. Ensure that induced
draft blower wheel is properly secured to motor shaft. Reset
unit at unit disconnect.

Internal control fault.
(LED 8 flashes)

Microprocessor has sensed an error in the soft-
ware or hardware.

If error code is not cleared by resetting unit power, replace the
IGC.

If the IGC must be replaced, be sure to ground yourself to dissi-
pate any electrical charge that may be present before handling
new control board. The IGC is sensitive to static electricity and
may be damaged if the necessary precautions are not taken.

IMPORTANT: Refer to Table 33 — Heating Service Analysis for
additional troubleshooting analysis.

IGC —

Integrated Gas Unit Controller

LED —

Light-Emitting Diode

TEMPERATURE

RESIST

ANCE

DEG. C 10 13 16 18 21 24 27 29 32 35 38

3000 OHMS AT 77

DEG. F (25 C)

OHMS