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Jeep Grand Cherokee WK. Manual - part 1779

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.

DIAGNOSIS AND TESTING

A/C COMPRESSOR

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 front engine bearing or connecting rod, may be caused by loose bolts, nuts, mounting
brackets or a loose compressor clutch assembly.

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 clutch is engaged, which may not occur when the compressor clutch is disengaged.
Check the accessory drive belt condition and tension as described in Cooling before beginning this procedure.

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

On and Off several times to clearly identify the compressor noise. Listen to the A/C compressor while the clutch
is engaged and disengaged. Probe the A/C compressor with an engine stethoscope or a long screwdriver with
the handle held to your ear to better localize the source of the noise.

2. Loosen all of the compressor mounting hardware and retighten. Check the compressor clutch retainer. Be certain

that the clutch field coil is mounted securely to the A/C compressor, and that the clutch plate and pulley are
properly aligned and have the correct air gap (Refer to 24 - HEATING & AIR CONDITIONING/CONTROLS/
CLUTCH-A/C COMPRESSOR - INSTALLATION).

3. To duplicate high-ambient temperature conditions (high head pressure), restrict the air flow through the A/C con-

denser. Install a manifold gauge set or a scan tool to be certain that the discharge pressure does not exceed
2760 kPa (400 psi).

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 - REFRIGER-
ANT LINES)

5. 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).

6. 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).

REMOVAL

3.7L/4.7L ENGINES

WARNING: Refer to the applicable warnings and cautions for this system before performing the following
operation (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - WARNINGS) and (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING - CAUTIONS). Failure to follow the warnings and cautions could result
in possible personal injury or death.

NOTE: The A/C compressor may be removed and repositioned without disconnecting the refrigerant lines or
discharging the refrigerant system. Discharging is not necessary if servicing the compressor clutch, clutch
coil, engine, engine cylinder head or the generator.

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PLUMBING

1. Recover the refrigerant from the refrigerant system

(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING

STANDARD

PROCEDURE

REFRIGERANT SYSTEM RECOVERY).

2. Disconnect and isolate the negative battery cable.

3. Remove the resonator from the air cleaner housing

and the engine (Refer to 9 - ENGINE/AIR INTAKE
SYSTEM/HOUSING-AIR CLEANER - REMOVAL).

4. Remove the accessory drive belt (Refer to 7 -

COOLING/ACCESSORY

DRIVE/BELTS-DRIVE

REMOVAL).

5. Remove the nuts (1) that secure the A/C discarge

line (4) and the A/C suction line (6) to the A/C com-
pressor (2).

6. Disconnect the refrigerant lines from the A/C com-

pressor and remove and discard the seals.

7. Install plugs in, or tape over all of the opened

refrigerant line fittings and the compressor ports.

8. Disconnect the wire harness connector from the

A/C compressor.

9. Loosen the bolt (5) that secures the bracket (7) to

the accessory mounting bracket (4).

10. Remove the bolts (1, 6 and 3) that secure the A/C

compressor

(2)

the

accessory

mounting

bracket.

11. Remove the A/C compressor from the engine

compartment.

5.7L ENGINE

PLUMBING

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1. Recover the refrigerant from the refrigerant system

(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING

STANDARD

PROCEDURE

REFRIGERANT SYSTEM RECOVERY).

2. Disconnect and isolate the negative battery cable.

3. Remove the resonator from the air cleaner housing

and engine (Refer to 9 - ENGINE/AIR INTAKE
SYSTEM/HOUSING-AIR CLEANER - REMOVAL).

4. Remove the accessory drive belt (Refer to 7 -

COOLING/ACCESSORY

DRIVE/BELTS-DRIVE

REMOVAL).

5. Remove the nuts (2) that secure the A/C discharge

line (1) and A/C suction line (3) to the A/C com-
pressor (4).

6. Disconnect the refrigerant lines from the A/C com-

pressor and remove and discard the seals.

7. Install plugs in, or tape over all of the opened

refrigerant line fittings and the compressor ports.

8. Remove the three bolts (1) that secure the power

steering pump (2) to the engine and position the
pump out of the way (Refer to 19 - STEERING/
PUMP - REMOVAL).

9. Disconnect the wire harness connector (3) from the

A/C compressor (5).

10. Support the A/C compressor and remove the bolts

(4) that secure the compressor to the engine.

11. Remove the A/C compressor from the engine

compartment.

INSTALLATION

3.7L/4.7L ENGINES

NOTE: If a replacement A/C compressor is being installed, be certain to check the refrigerant oil level. See
Refrigerant Oil Level in this group for the procedures. Use only refrigerant oil of the type recommended for
the A/C compressor in the vehicle.

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PLUMBING

1. Position the A/C compressor (2) onto the accessory

mounting bracket (4).

2. Install and tighten the bolts in the following

sequence:

•

Install bolt (3) and hand tighten.

•

Install bolt (6) and hand tighten.

•

Install bolt (1) and hand tighten.

•

Tighten bolt (3) to 40 N·m (30 ft. lbs.).

•

Tighten bolt (6) to 55 N·m (41 ft. lbs.).

•

Tighten bolt (1) to 55 N·m (41 ft. lbs.).

•

Tighten bolt (5) to 55 N·m (41 ft. lbs.).

3. Connect the wire harness connector to the A/C

compressor clutch coil connector.

4. Remove the tape or plugs from the opened refrig-

erant line fittings and the compressor ports.

5. Lubricate new seals with clean refrigerant oil and

install them onto the refrigerant line fittings. Use
only the specified seals as they are made of a spe-
cial material for the R-134a system. Use only
refrigerant oil of the type recommended for the A/C
compressor in the vehicle.

6. Install the A/C suction line (6) and the A/C dis-

charge line (4) onto the A/C compressor (2).

7. Install the nuts (1) that secure the refrigerant lines

to the A/C compressor. Tighten the nuts to 20 N·m
(15 ft. lbs.).

8. Install the accessory drive belt (Refer to 7 - COOL-

ING/ACCESSORY DRIVE/BELTS-DRIVE - INSTAL-
LATION).

9. Install the resonator onto the engine and air

cleaner housing (Refer to 9 - ENGINE/AIR INTAKE
SYSTEM/HOUSING-AIR CLEANER - INSTALLA-
TION).

10. Reconnect the negative battery cable.

11. Evacuate the refrigerant system (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STANDARD

PROCEDURE - REFRIGERANT SYSTEM EVACUATE).

12. Charge the refrigerant system (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STANDARD PRO-

CEDURE - REFRIGERANT SYSTEM CHARGE).

5.7L ENGINE

NOTE: Be certain to check the refrigerant oil level if the A/C compressor is being replaced. See Refrigerant
Oil Level in this group for the procedures. Use only refrigerant oil of the type recommended for the A/C
compressor in the vehicle.

PLUMBING

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