Dodge Ram Truck 1500-2500-3500. Manual — part 2056

7. Install the clutch plate (2) onto the compressor

shaft.

8. Install the compressor shaft bolt (1). Tighten the

bolt to 17.5 N·m (155 in. lbs.).

NOTE: The shims may compress after tightening
the shaft bolt. Check the air gap in four or more
places to verify the air gap is correct. Spin the pul-
ley before performing a final check of the air gap.

9. With the clutch plate assembled tight against the

shim(s), measure the air gap between the clutch
plate and the pulley and bearing assembly faces
with a feeler gauge. The air gap should be between
specifications (Refer to 24 - HEATING & AIR CON-
DITIONING - SPECIFICATIONS). If the proper air
gap is not obtained, add or subtract shims as
needed until the desired air gap is obtained.

10. Install the bolts that secure the A/C compressor to

the engine (Refer to 24 - HEATING & AIR CON-
DITIONING/PLUMBING/COMPRESSOR-A/C

-

INSTALLATION).

11. Connect the engine wire harness connector to the A/C compressor clutch coil.

12. Install the accessory drive belt (Refer to 7 - COOLING/ACCESSORY DRIVE/BELTS-DRIVE - INSTALLATION).

13. Reconnect the negative battery cable.

CONTROL-A/C HEATER

DESCRIPTION

MANUAL SINGLE ZONE

The A/C-heater control (1) for the manual temperature
control (MTC) single zone heating-A/C system allows
one temperature setting for the entire vehicle. All con-
trols are identified by ISO graphic symbols.

NOTE: Manual A/C-heater control with optional A/C
shown. Manual A/C-heater control without A/C sim-
ilar.

The A/C-heater control and integral computer is
located in the instrument panel and contains:

•

a push button A/C on/off control (2). The Snow-
flake button contains an LED that illuminates
when the optional A/C system is in operation.

•

a push button rear window defogger on/off control (3). The defogger button contains an LED that illuminates
when the rear window defogger system is in operation.

•

a rotary control knob for recirculation and mode control of the discharged air (4).

•

a rotary control knob for temperature control of the discharged air (5).

•

a rotary control knob for fan speed selection and turning the heating-A/C system off (6).

Refer to 24 - HEATING & AIR CONDITIONING - DIAGNOSIS AND TESTING and to 24 - HVAC Electrical Diag-
nostics for more information.

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The A/C-heater control cannot be repaired and, if faulty or damaged, it must be replaced. The illumination lamps for
the A/C-heater control are available for service replacement.

MANUAL DUAL ZONE

The A/C-heater control (4) for the manual temperature
control (MTC) dual zone heating-A/C system allows
both the driver and the front seat passenger the ability
to individually regulate air temperature for their side of
the vehicle. All controls are identified by ISO graphic
symbols.

The dual zone A/C-heater control and integral com-
puter is located in the instrument panel and contains:

•

a push button A/C on/off control (1). The Snow-
flake button contains an LED that illuminates
when the A/C system is in operation.

•

a push button MAX A/C air recirculation control
(2). The Recirculation button contains an LED
that illuminates when the recirculation function is activated for high A/C demand.

•

a push button rear window defogger on/off control (3). The defogger button contains an LED that illuminates
when the rear window defogger system is in operation.

•

two slid-type control levers for individual driver and front seat passenger temperature control of the discharged
air (5 and 6).

•

a rotary control knob for mode control of the discharged air (7).

•

a rotary control knob for fan speed selection and turning the heating-A/C system off (8).

Refer to 24 - HEATING & AIR CONDITIONING - DIAGNOSIS AND TESTING and to 24 - HVAC Electrical Diag-
nostics for more information.

The A/C-heater control cannot be repaired and, if faulty or damaged, it must be replaced.

REMOVAL

WARNING: On vehicles equipped with airbags, dis-
able the airbag system before attempting any
steering wheel, steering column, or instrument
panel component diagnosis or service. Disconnect
and isolate the battery negative (ground) cable,
then wait two minutes for the airbag system
capacitor to discharge before performing further
diagnosis or service. This is the only sure way to
disable the airbag system. Failure to take the
proper precautions could result in an accidental
airbag deployment and possible personal injury or
death.

1. Disconnect and isolate the negative battery cable.

2. Remove the center bezel from the instrument panel and disconnect the wire harness connectors (3 and 4) from

the A/C-heater control (1) (Refer to 23 - BODY/INSTRUMENT PANEL/INSTRUMENT PANEL CENTER BEZEL -
REMOVAL).

3. Place the center bezel on a workbench and remove the screws (2) that secure the A/C-heater control to the

center bezel.

4. Remove the A/C-heater control from the center bezel.

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INSTALLATION

1. Position the A/C-heater control (1) into the instru-

ment panel center bezel.

2. Install the screws (2) that secure the A/C-heater

control to the center bezel. Tighten the screws to 2
N·m (17 in. lbs.).

3. Connect the wire harness connectors (3 and 4) to

the back of the A/C-heater control (5) and install
the instrument panel center bezel (Refer to 23 -
BODY/INSTRUMENT

PANEL/INSTRUMENT

PANEL CENTER BEZEL - INSTALLATION).

4. Reconnect the negative battery cable.

RELAY-CLUTCH-A/C COMPRESSOR

DESCRIPTION

The A/C clutch relay (1) is a International Standards
Organization (ISO) micro-relay. Relays conforming to
the ISO specifications have common physical dimen-
sions, current capacities, terminal functions and pat-
terns (2). The ISO micro-relay terminal functions are
the same as a conventional ISO relay. However, the
ISO micro-relay terminal pattern (or footprint) is differ-
ent, the current capacity is lower, and the physical
dimensions are smaller than those of the conventional
ISO relay.

The A/C clutch relay is located in the integrated power
module (IPM) in the engine compartment.

OPERATION

The ISO-standard A/C clutch micro-relay is an electromechanical switch that uses a low current input from the pow-
ertrain control module (PCM) or engine control module (ECM) (depending on engine application), to control the high
current output to the A/C clutch field coil. The movable, common feed relay contact is held against the fixed, nor-
mally closed relay contact by spring pressure. When the electromagnetic relay coil is energized, it draws the mov-
able common feed relay contact away from the fixed, normally closed relay contact and, holds it against the fixed,
normally open relay contact. This action allows high current to flow to the A/C clutch field coil.

When the relay coil is de-energized, spring pressure returns the movable relay contact back against the fixed, nor-
mally closed contact point. The resistor or diode is connected in parallel with the relay coil, and helps to dissipate
voltage spikes and electromagnetic interference that can be generated as the electromagnetic field of the relay coil
collapses.

The A/C clutch relay terminals are connected to the vehicle electrical system through a receptacle in the integrated
power module (IPM). The inputs and outputs of the A/C clutch relay include:

•

The common feed terminal (30) receives a battery current input from a fuse in the IPM through a fused B(+)
circuit at all times.

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•

The coil ground terminal (86) receives a ground input from the PCM/ECM through the A/C clutch relay control
circuit only when the PCM/ECM electronically pulls the circuit to ground.

•

The coil battery terminal (85) receives a battery current input from PTC 1 in the IPM through a fused ignition
switch output (run) circuit only when the ignition switch is in the On position.

•

The normally open terminal (87) provides a battery current output to the A/C clutch coil through the A/C clutch
relay output circuit only when the A/C clutch relay coil is energized.

•

The normally closed terminal (87A) is not connected to any circuit in this application, but provides a battery
current output only when the A/C clutch relay coil is de-energized.

The A/C clutch relay cannot be repaired and, if faulty or damaged, it must be replaced. Refer to the appropriate
wiring information for diagnosis and testing of the ISO-standard micro-relay and for complete HVAC wiring diagrams.

REMOVAL

1. Disconnect and isolate the negative battery cable

(1).

2. Remove the cover from the integrated power mod-

ule (IPM) (2).

NOTE: Refer to the fuse and relay layout map on
the inside of the IPM cover for A/C clutch relay
location.

3. Remove the A/C clutch relay from the IPM.

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