Dodge Caliber. Manual - part 1427

COMPRESSOR-A/C

DESCRIPTION

A/C COMPRESSOR

The A/C system uses a Denso 5SE12C clutchless,
five cylinder, variable displacement swashplate type
A/C compressor (1). This A/C compressor has a total
displacement of 126 cubic centimeters (7.6 cubic
inches) and a high pressure relief valve (2) and a con-
trol valve (3) located on the back cover. The A/C com-
pressor is secured with three bolts to the compressor
bracket located near the oil pan at the front of the
engine.

A label identifying the use of R-134a refrigerant is
located on the A/C compressor.

HIGH PRESSURE RELIEF VALVE

A high pressure relief valve is located on the compressor cylinder head, which is at the rear of the A/C compressor
(refer to 24 - HEATING & AIR CONDITIONING/PLUMBING/COMPRESSOR-A/C - DESCRIPTION). This mechanical
valve is designed to vent refrigerant from the A/C system to protect against damage to the A/C compressor and
other A/C system components, caused by condenser air flow restriction or an overcharge of refrigerant.

HUB AND PULLEY

NOTE: Typical A/C compressor pulley and drive hub shown.

The A/C compressor hub and pulley assembly pro-
vides the means to drive the A/C compressor using
the engine accessory drive belt. The hub and pulley
assembly consists of an aluminum drive hub (1) with
composite tabs (2) that are positioned between rubber
dampeners (3) which are located inside of a compos-
ite pulley (4).

The A/C pulley has a non-servicable bearing (5) which
is retained to the nose of the A/C compressor with a
snap ring (6). The drive hub and shim (7) are retained
to the compressor shaft by use of left handed threads.

PLUMBING

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OPERATION

A/C COMPRESSOR

The 5SE12C A/C compressor is a variable displace-
ment compressor (VDC) which is driven by the engine
through a drive hub (1) and pulley (2). This A/C com-
pressor does not require the use of an electromag-
netic clutch, as the compressor uses an integral
control solenoid (3) to reduce or increase the stroke of
the five pistons (4) within the compressor by automat-
ically adjusting the angle of the swashplate (5).

The A/C compressor draws in low-pressure refrigerant
vapor from the A/C evaporator through its suction port.
It then compresses the refrigerant into a high-pres-
sure, high-temperature refrigerant vapor, which is then
pumped to the A/C condenser through the compressor
discharge port. The A/C compressor is lubricated by
refrigerant oil that is circulated throughout the refriger-
ant system with the refrigerant (refer to 24 - HEATING
&

AIR

CONDITIONING/PLUMBING/REFRIGERANT

OIL - DESCRIPTION).

The A/C compressor is controlled by the powertrain
control module (PCM) or engine control module (ECM), depending on engine application. The PCM/ECM calculates
compressor displacement required by A/C system load and demand by monitoring vehicle speed, A/C high side
pressure, engine speed, evaporator temperature, accelerator pedal position, ambient temperature and A/C-heater
request signals. The PCM/ECM then sends a pulse width modulated (PWM) signal to the A/C compressor control
solenoid to increase or decrease refrigerant flow through an orifice located within the compressor housing. The
amount of refrigerant allowed to pass through the orifice in the compressor determines the head pressure which
controls the angle of the swashplate, which in turn, determines the amount of compressor displacement. When there
is no demand for A/C, the swashplate is adjusted to nearly a zero degree angle, which removes compressor torque
drag from the engine.

This A/C compressor will reduce the displacement of the compressor based on ambient air temperature. For exam-
ple; as the outside temperature falls from 27° C (80° F) to 19° C (66° F), the amount of refrigerant flow required
through the A/C orifice valve to keep the A/C evaporator cool becomes less, and the swashplate is adjusted to a
lower angle, which reduces compressor displacement. However, due to the lower outside air temperature, panel air
outlet temperature will not noticeably change.

The A/C compressor control system is diagnosed using a scan tool (refer to 24 - HEATING & AIR CONDITIONING
- DIAGNOSIS AND TESTING and to 24 - HVAC Electrical Diagnostics for more information).

CAUTION: Do NOT run the engine with a vacuum pump in operation or with a vacuum present within the
A/C system. Failure to follow this caution will result in serious A/C compressor damage.

CAUTION: Be certain to check and adjust the refrigerant system oil level when replacing an A/C compressor
(refer to 24 - HEATING & AIR CONDITIONING/PLUMBING/REFRIGERANT OIL - STANDARD PROCEDURE -
REFRIGERANT OIL LEVEL). Failure to properly adjust the refrigerant oil level can prevent the A/C system
from operating as designed and can cause serious A/C compressor damage.

NOTE: The A/C compressor pulley and bearing assembly can be serviced separately in the event of damage
or wear to the pulley or bearing. However, the compressor drive hub itself is not serviceable. In the event of
drive hub failure, the A/C compressor, drive hub and pulley and bearing must be replaced as an assembly.

The A/C compressor cannot be repaired and, if faulty or damaged it must be replaced. If an internal failure of the
A/C compressor has occurred, the A/C accumulator must also be replaced (refer to 24 - HEATING & AIR CONDI-
TIONING/PLUMBING/ACCUMULATOR-A/C - DESCRIPTION).

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PLUMBING

HIGH PRESSURE RELIEF VALVE

The high pressure relief valve vents refrigerant from the A/C system when a discharge pressure of 3445 to 4135
kPa (500 to 600 psi) or above is reached. The high pressure relief valve closes with a minimum discharge pressure
of 2756 kPa (400 psi) is reached.

The high pressure relief valve vents only enough refrigerant to reduce the A/C system pressure, and then re-seats
itself. The majority of the refrigerant is conserved in the A/C system. If the high pressure relief valve vents refrig-
erant, it does not mean the valve is faulty.

The high pressure relief valve is factory-calibrated and cannot be adjusted or repaired, and must not be removed or
otherwise disturbed. The valve is only serviced as a part of the A/C compressor.

HUB AND PULLEY

NOTE: Typical A/C compressor pulley drive hub shown in illustration.

This compressor design does not require the use of
an electromagnetic clutch, as the compressor is con-
trolled by an integral control valve that allows refriger-
ant to bypass within the compressor (refer to 24 -
HEATING

AIR

CONDITIONING/PLUMBING/A/C

COMPRESSOR - DESCRIPTION).

The three bridges (1) located on compressor drive hub
(2) are designed to break away in the event of com-
pressor seizure. This action prevents damage to the
serpentine accessory drive belt (refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING/HUB AND
PULLEY-A/C COMPRESSOR - INSPECTION).

NOTE: The A/C compressor pulley and bearing
assembly can be serviced separately in the event
of damage or wear to the pulley or bearing. How-
ever, the compressor drive hub itself is not ser-
viceable. In the event of drive hub failure, the A/C
compressor, drive hub and pulley and bearing
must be replaced as an assembly.

The A/C compressor pulley and bearing cannot be repaired and, if faulty or damaged it must be replaced. The A/C
compressor pulley and bearing is available for service in the event of pulley damage or pulley bearing failure. If an
internal failure of the A/C compressor has lead to compressor seizure, the compressor, hub and pulley must be
replaced as an assembly.

DIAGNOSIS AND TESTING

A/C COMPRESSOR NOISE TESTING

When investigating an A/C system related noise, you must first know the conditions under which the noise occurs.
These conditions include: weather, vehicle speed, transmission in gear or neutral, engine speed, engine tempera-
ture, and any other special conditions. Noises that develop during A/C operation can often be misleading. For exam-
ple: what sounds like a failed bearing, may be caused by loose bolts, nuts, mounting brackets or a loose
compressor assembly.

NOTE: The A/C compressor must be replaced if any unusual noise is heard from the compressor itself.

1. Select a quiet area for testing. Duplicate the complaint conditions as much as possible. Turn the A/C system On

and Off several times to clearly identify any compressor noise. Listen to the A/C compressor while it is operating
at maximum and minimum displacement. Probe the A/C compressor with an engine stethoscope or a long screw-
driver with the handle held to your ear to better localize the source of the noise. To duplicate high-ambient tem-
perature conditions (high head pressure), restrict the air flow through the A/C condenser. Install a manifold gauge
set or a scan tool to be certain that the discharge pressure does not exceed 2600 kPa (377 psi).

PLUMBING

24 - 127

NOTE: Drive belts are speed sensitive. At different engine speeds and depending upon drive belt tension,
drive belts can develop noises that are mistaken for an A/C compressor noise. Improper drive belt tension
can cause a misleading noise when the compressor is operating at maximum displacement, which may not
occur when the compressor is at minimum displacement.

2. Check the condition of the accessory drive belt (refer to 7 - COOLING/ACCESSORY DRIVE/DRIVE BELTS -

DIAGNOSIS AND TESTING).

NOTE: The A/C compressor must be replaced if the drive hub is broken or if the compressor shaft does not
rotate smoothly.

3. Check the compressor hub and pulley and bearing assembly. Be certain that the hub and pulley are properly

aligned and that the pulley bearing is mounted securely to the A/C compressor (refer to 24 - HEATING & AIR
CONDITIONING/PLUMBING/COMPRESSOR-A/C-HUB AND PULLEY - INSPECTION).

NOTE: The A/C compressor must be replaced if any debris or unusually discolored oil is found on the A/C
compressor manifold.

4. Check the refrigerant system plumbing for incorrect routing, rubbing or interference, which can cause unusual

noises. Also check the refrigerant lines and hoses for kinks or sharp bends that will restrict refrigerant flow, which
can cause noises (refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - DESCRIPTION - REFRIGERANT
LINES).

5. Loosen all of the compressor mounting hardware and retighten.

CAUTION: Do NOT run the engine with a vacuum pump in operation or with a vacuum present within the
A/C system. Failure to follow this caution will result in serious A/C compressor damage.

6. If the noise is from opening and closing of the high pressure relief valve, recover, evacuate and recharge the

refrigerant system (refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STANDARD PROCEDURE -
REFRIGERANT SYSTEM RECOVERY), (refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STAN-
DARD PROCEDURE - REFRIGERANT SYSTEM EVACUATE) and (refer to 24 - HEATING & AIR CONDITION-
ING/PLUMBING - STANDARD PROCEDURE - REFRIGERANT SYSTEM CHARGE). If the high pressure relief
valve still does not seat properly, replace the A/C compressor (refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING/COMPRESSOR-A/C - REMOVAL).

7. If the noise is from liquid refrigerant slugging in the A/C suction line, replace the A/C accumulator (refer to 24 -

HEATING & AIR CONDITIONING/PLUMBING/ACCUMULATOR-A/C - REMOVAL) and check the refrigerant oil
level and the refrigerant system charge (refer to 24 - HEATING & AIR CONDITIONING/PLUMBING/REFRIGER-
ANT OIL - STANDARD PROCEDURE - REFRIGERANT OIL LEVEL).

If a slugging condition still exists after replacing the A/C accumulator, then replace the A/C compressor (refer to

24 - HEATING & AIR CONDITIONING/PLUMBING/COMPRESSOR-A/C - REMOVAL).

REMOVAL

PULLEY AND BEARING

WARNING: Review safety precautions and warnings in this group before performing this procedure (refer to
24 - HEATING & AIR CONDITIONING/PLUMBING - WARNING) and (refer to 24 - HEATING & AIR CONDITION-
ING/PLUMBING - CAUTION). Failure to follow the warnings and cautions could result in possible personal
injury or death.

NOTE: The A/C compressor pulley and bearing assembly can be serviced in the vehicle. The refrigerant
system can remain fully charged during pulley and bearing replacement.

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PLUMBING

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