•
Stored DTCs are those which occurred in the
system since the ATC Module received the last
9clear diagnostic info9 message.
The AC Cooldown Test:
•
is actuated with the DRBIII
t.
•
checks A/C system performance based on evapo-
rator temperature sensor input.
•
forces the ATC to initiate the Cabin Heater Acti-
vation request when the vehicle is equipped with
a Diesel Cabin Heater Assist.
WARNING: DO NOT OPERATE THE DCHA IN
AN ENCLOSED AREA SUCH AS A GARAGE
THAT
DOES
NOT
HAVE
EXHAUST
VENTILATION FACILITIES. ALWAYS VENT
THE DCHA’s EXHAUST WHEN OPERATING
THE
DCHA.
REFER
TO
VENTING
THE
DCHA’s EXHAUST UNDER CABIN HEATER IN
THE GENERAL INFORMATION PORTION OF
THIS
SECTION
FOR
PROPER
EXHAUST
VENTING
INSTRUCTIONS.
FAILURE
TO
FOLLOW
THESE
INSTRUCTIONS
CAN
RESULT IN PERSONAL INJURY OR DEATH.
CAUTION: Do not activate the A/C Cooldown
Test with the engine off. Failure to follow
these instructions can result in internal
damage to the DCHA Heater Module.
c
The FCM monitors the PCI bus for the Cabin
Heater Activation request. The request car-
ries the status bit that the FCM requires to
activate its’ Cabin Heater Assist Control out-
put. This output is a low side driver (coming
from FCM pin 15) which supplies a ground
signal to the Cabin Heater (pin 5). When the
Cabin Heater receives this ground signal in-
put, it interprets this as an activation signal.
c
The FCM low side driver is also capable of
diagnostic sensing. The driver will sense an
open circuit when the driver is off, and will
sense a short to voltage when the driver is on.
The FCM will set DTCs for both of these types
of faults. For additional information, refer to
Cabin Heater under General Information and
Diagnostic Procedures in the manual.
•
will not run the air conditioning portion of this
test if ambient temperature is below 12°C (53°F).
c
The forced Cabin Heater activation will occur
even if the air conditioning portion of this test
fails to initiate because AC Cooldown test
criteria was not met. When activated, the
DCHA will operate for approximately seven
minutes. Three minutes to run and four min-
utes to purge.
•
will pass the air conditioning portion of this test
if the evaporator temperature drops 6.7°C (20°F)
within two minutes of starting this test.
•
messages (air conditioning related only) display
on the DRBIII
t after running this test.
c
These messages will clear after paging back
out of this test. Therefore, it is important to
note all of the AC Cooldown test messages
before doing so.
c
All Cabin Heater-related DTCs display under
Cabin Heater, Read DTCs.
•
will cause the DELAY and Snowflake VF seg-
ments on the ATC to flash for 162 seconds (RG
with DCHA only). If the air conditioning portion
of this test fails, the DELAY and Snowflake VF
segments will continue to flash until the vehicle
is driven more than three miles.
3.10.2
MANUAL TEMPERATURE CONTROL
(MTC)
3.10.2.1
MODULE USAGE
VEHICLE COMPATIBILITY
FOR MTC MODULES
MODEL
YEAR
SOFTWARE
VERSION*
RS
2001, 2002
0614, 0700
2003
0802**
2004
0812, 0900
2005
0900
RG
2001, 2002
0614, 0700
2003 – 2005
0802**
* Use The DRBIII
t to verify which version soft-
ware the module is using by selecting Module
Display from the ATC menu.
Installing a module with software that is
incompatible for a given model year can
result in either improper or failed HVAC
system operation.
** Backward compatible.
3.10.2.2
SYSTEM AVAILABILITY
EXCEPT EXPORT
•
Three different types of systems are currently
available for these vehicles.
c
Single-Zone Air Conditioning System
21
GENERAL INFORMATION