SECTION 22: HEATING AND AIR CONDITIONING
16
DOB 2490-2789 | X3-45 Commuter PA1605 Maintenance Manual (Final Version – Rev.2 April 2016)
5.5
HVAC SYSTEM MULTIPLEX TROUBLESHOOTING
Problem/Symptom
Probable Causes
Actions
Defroster fan not functioning
Module A47 is not powered or is
faulty
Module A24 is not powered or is
faulty
1. Check the Diagnostics menu of the Driver
Information Display (DID). Select Fault
Diagnostics and Electrical System. The
message “No Response ModA47 (or
ModA24), Active” indicates a power
problem on the module. (A CAN network
problem would show the same message
but doesn't produce these symptoms).
2. Check / reset circuit breaker CB1
3. Check
CB16V
(VECF)
4. Probe gray connector on module to see if
it is powered.
HVAC condenser fans not
functioning
Circuit breaker CB7 tripped
Seized bearing
Bad wiring
Module A54 is not powered or is
faulty
1. Check / reset circuit breaker CB7
2. Check/reset CB15, CB16, CB17, CB18 on
HVAC control module
3. Check / replace condenser power relay
R10 (probe R10 coil power circuit 67A,
should be 24 volts).
4. Check the Diagnostics menu of Driver
Information Display (DID). Select Fault
Diagnostics and Electrical System. The
message “No Response ModA54, Active”
indicates a power problem on the module.
(A CAN network problem would show the
same message but doesn't produce this
symptom).
5. Check CB5, CB67.
HVAC condenser fans not
functioning in speed 1
Module A42 is not powered or is
faulty
1. Check the Diagnostics menu of Driver
Information Display (DID). Select Fault
Diagnostics and Electrical System. The
message “No Response ModA42, Active”
indicates a power problem on the module.
(A CAN network problem would show the
same message but doesn't produce this
symptom).
2. Check / reset circuit breaker CB1, CB5,
CB7
3. Check
CB67
4. Probe gray connector on module to see if
it is powered.
HVAC condenser fans not
functioning in speed 2
Circuit breaker CB7 tripped
Seized bearing
Bad wiring
1. Check / reset circuit breaker CB7
2. See
HVAC condenser fans not functioning
&
HVAC condenser fans not functioning in
speed 1
above.
Defroster fan is functioning
but no heat or cooling
Module A46 is not powered or is
faulty
1. Check the Diagnostics menu of Driver
Information Display (DID). Select Fault