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AUTOMATIC TEMPERATURE CONTROL
*HVAC SYSTEM TEST —
TEST
6
WARNING: DO NOT OPERATE THE DCHA IN AN ENCLOSED AREA SUCH
AS A GARAGE THAT DOES NOT HAVE EXHAUST VENTILATION FACILI-
TIES. ALWAYS VENT THE DCHA's EXHAUST WHEN OPERATING THE
DCHA. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN
PERSONAL INJURY OR DEATH.
NOTE: For RG vehicles equipped with a Diesel Cabin Heater Assist (DCHA),
refer to Venting the DCHA's Exhaust under Cabin Heater in the General
Information portion of this manual for proper exhaust venting instructions.
NOTE: The AC Cooldown Test is actuated with the DRBIII . The test checks
A/C system performance based on evaporator temperature sensor input. It
also forces the ATC to initiate a Cabin Heater Activation request when the
vehicle is equipped with a DCHA.
NOTE: The A/C related portion of this test will not run if ambient temp is
below 12°C (53°F). However, the forced Cabin Heater activation will occur
even if the A/C portion of this test fails to initiate because test criteria was
not met.
NOTE: The A/C related portion of this test will pass if evap temp drops 6.7°C
(20°F) within 2 minutes of starting this test.
NOTE: Only A/C related messages display on the DRBIII after running this
test. These messages will clear after paging back out of this test. Therefore,
it is important to note all of the test messages before doing so.
NOTE: Running this test will cause the DELAY & Snowflake on the ATC to
flash for 162 seconds (RG with DCHA only). If the A/C related portion of this
test fails, the DELAY & Snowflake LED will continue to flash until the
vehicle is driven more than 3 miles.
Start the engine.
Press the ATC's Power switch on.
Turn the Mode control to the panel position.
Verify that the front blower motor and, if equipped, rear blower motor operate
correctly in all speeds from each control. Diagnose and repair all blower related faults
before proceeding with this test.
Turn the Front Blower control to the high speed position.
Set the Driver, Pass, and, if equipped, Rear temperature controls to 72°F (22°C).
CAUTION: Do not activate the A/C Cooldown Test with the engine off.
Failure to follow these instructions may result in internal damage to the
DCHA Heater Module.
NOTE: Do not disconnect the vehicle's battery or the DCHA's main power
supply while the DCHA is in operation or in run-down mode. Failure to
follow these instructions may result in excess emissions from the DCHA
during heater operation.
NOTE: Before actuating the AC Cooldown Test, verify that the A/C compres-
sor is not running, If the compressor is running, turn the A/C off and allow
the evaporator to warm up before proceeding with the test.
NOTE: The DCHA, if equipped, will operate for approximately 7 minutes. 3
minutes to run and 4 minutes to purge.
With the DRBIII in ATC, Systems Tests, perform the AC Cooldown Test.
Does the DRBIII display any Cooldown Test fault messages?
Yes → Return to the symptom list and choose the symptom(s)
→ Go To 7
No
Continued
ACTION
Perform BODY VERIFICATION TEST - VER 1.
270
APPLICABILITY
All
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