Table of Contents
Advertisement
Slave board configuration
In some large systems where the electrical load exceeds the current capability of a single
board, a slave board can be used. A typical wiring diagram is 5031xxxx. In a slave system,
the switches are connected to the master board and the slave board is connected to the master
board through a harness 701442. The slave board mimics the actions of the master board.
The slave board normally is used to drive the additional evaporators and condensers.
Trouble shooting
Use Table 8 to identify the problem if there is a fault code. Other common problems are
listed in Table 9. Refer to previous sections for detailed action procedures.
Table 9 Trouble Shooting
Symptom
Switch does not turn on
Clutch does not engage
Fan / Blower do not run
Blower does not stop
Fault code persists
Thermostat shows Lo all the
time
Thermostat shows Hi all the
time
Probable causes
No power
Faulty communication cable Replace cable
Faulty switch
Faulty board
Tset> Tin
Faulty external temperature
sensor
Bad connection
Faulty board
Bad connection
Faulty board
Faulty board
Bad connection
Fault condition persists
1000 hr service timer
Faulty board
Low cabin temperature
Temperature sensor cable
short
Faulty temperature sensor
High cabin temperature
Temperature sensor open
circuit
Faulty temperature sensor
EC3 Service Manual Jan. 8, 2008
Action
Check COM LED
Check terminal 5 for +12vdc
and 10 for ground
Replace switch
Replace board
Adjust set point
Replace temp. sensor or
sensor cable
Check LED on board and
voltage on terminal 1
Replace board
Check LED and power
output terminal
Replace board
Replace board
Check safety harness
connections at evap. & board
Check pressure and voltage
Reset service timer
Replace board
Verify cabin temperature is
below 60ºF
Verify shortage
Repair or replace cable
Replace sensor
Verify cabin temperature is
above 90ºF
Verify open circuit
Repair or replace cable
Replace sensor
6
Advertisement
Table of Contents
