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3.9.2 MANUAL TEMPERATURE CONTROL
(MTC)
CAUTION:
Manual
(MTC) Modules with software versions 0614
and 0700 used in 2001 and 2002 RS/RG
vehicles are NOT compatible with software
version 0802 used in 2003 RS/RG vehicles.
Do NOT install an MTC Module with software
version 0614 or 0700 in a 2003 RS/RG vehicle.
Use the DRBIII
to verify which version
software the MTC Module is using by
selecting Body Systems, HVAC, and then
selecting Module Display.
3.9.2.1 SYSTEM AVAILABILITY
EXCEPT EXPORT
•
Three different types of systems are currently
available for these vehicles.
Single-Zone Air Conditioning System
Dual-Zone Air Conditioning System
Three-Zone Air Conditioning System
EXPORT
•
Two different types of systems are currently
available for these vehicles.
Single-Zone Air Conditioning System
Dual-Zone Air Conditioning System
CABIN HEATER, EXPORT WITH DIESEL ENGINE
•
A Cabin Heater is used in conjunction with the
HVAC system. The Cabin Heater is designed to
supply the vehicle's occupants with heat prior to
the engine reaching operating temperature. For
additional information on this system, refer to
Cabin Heater under General Information and
Diagnostic Procedures in this manual.
3.9.2.2 SYSTEM CONTROLS
The A/C-Heater Control Module:
•
is fully addressable with the DRBIII .
•
communicates over the Programmable Commu-
nication Interface Multiplex System (PCI) Bus.
•
provides an A/C request to the Powertrain Con-
trol Module (PCM) over the PCI Bus when com-
pressor operation is desired.
•
uses input from the evaporator temperature sen-
sor to prevent evaporator freeze up while main-
taining optimum cooling performance.
•
for exports with diesel engines, provides a Cabin
Heater activation request to the Front Control
Temperature
Control
GENERAL INFORMATION
Module (FCM) over the PCI Bus when conditions
are favorable for Cabin Heater operation.
•
provides a blower relay on request to the Front
Control Module (FCM) over the PCI Bus when
blower operation is desired.
•
controls front blower operating speed. The five
speed settings are Low, M1, M2, M3, and High.
•
controls EBL operation.
•
on three-zone systems, activates and deactivates
the Rear A/C-Heater Control.
•
on three-zone systems, controls rear blower oper-
ating speed. The three speed settings are Low,
Med, and High.
•
controls the front and the three-zone system rear
electronic door actuators' operation.
A simplified control system for operation of
the mode, recirculation, and temperature con-
trol actuators provides positive positioning
without the complexity of feedback from posi-
tion sensors. The A/C - Heater Control Module
knows the number of operating actuator rev-
olutions required for full door travel as well as
the number of actuator commutator pulses
per revolution. Using these parameters, the
A/C - Heater Control Module runs the actua-
tor for the number of commutator pulses that
correspond to the desired door position. To
maintain accuracy, the system recalibrates
itself periodically at known zero and full
travel conditions.
On Three-Zone systems, the Rear A/C-Heater Con-
trol:
•
controls rear blower motor operating speed. The
three blower speeds are Low, Med, and High.
•
provides desired rear blend and mode door posi-
tion input to the A/C-Heater Control Module.
The Single-Zone HVAC system uses:
•
one, two-wire electronic blend door actuator.
•
one, two-wire electronic mode door actuator.
•
one, two-wire electronic recirculation door actua-
tor.
The Dual-Zone HVAC system uses:
•
two, two-wire electronic blend door actuators.
•
one, two-wire electronic mode door actuator.
•
one, two-wire electronic recirculation door actua-
tor.
The Three-Zone HVAC system uses:
•
two front, two-wire electronic blend door actua-
tors.
•
one front, two-wire electronic mode door actuator.
19
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