High Pressure Relief Valve; A/C Compressor; Diagnosis And Testing; A/C Compressor Noise - Chrysler Sebring 2005 Service Manual

24 - 62 PLUMBING
A/C COMPRESSOR (Continued)
CAUTION: The refrigerant oil in the R-134a A/C sys-
tem is unique depending on the A/C compressor
used. Use only PAG oils that are designed to work
with R-134a refrigerant and the A/C compressor in
the vehicle. Always refer to the underhood A/C Sys-
tem Specification Label for the correct oil designa-
tion.
Both A/C systems uses polyalkylene glycol syn-
thetic wax-free refrigerant oil PAG (refer to the
underhood A/C system label for the correct oil type
for the A/C compressor used in the system (depend-
ing on engine application).

HIGH PRESSURE RELIEF VALVE

A mechanical high pressure relief valve is used 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.
On the TRS-090 A/C compressor, the relief valve is
located on the compressor cylinder head, which is on
the rear of the compressor. On the HS-15 A/C com-
pressor, the relief valve is located on the replaceable
compressor manifold.
OPERATION

A/C COMPRESSOR

The A/C compressor is driven by the engine
through an electric clutch, drive pulley and belt
arrangement. The A/C compressor is lubricated by
refrigerant oil that is circulated throughout the
refrigerant system with the refrigerant.
The A/C compressor draws in low-pressure refrig-
erant vapor from the A/C evaporator through its suc-
tion port. It then compresses the refrigerant into a
high-pressure, high-temperature refrigerant vapor.
The A/C compressor pumps the high-pressure refrig-
erant vapor to the A/C condenser through the com-
pressor discharge port.
The A/C compressor cannot be repaired and, if
faulty or damaged, the entire compressor assembly
must be replaced. The compressor clutch, pulley and
clutch coil are available for service.
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 relief valve closes when a minimum dis-
charge pressure of 2756 kPa (400 psi) is reached.
The high pressure relief valve vents only enough
refrigerant to reduce the system pressure, and then
re-seats itself. The majority of the refrigerant is con-
served in the A/C system. If the relief valve vents
refrigerant, it does not necessarly mean that the
valve is faulty.
The high pressure relief valve is a factory-cali-
brated unit. The relief valve cannot be adjusted or
repaired, and must not be removed or otherwise dis-
turbed. On the TRS-090 A/C compressor, the relief
valve is serviced only as a part of the compressor
assembly. On the HS-15 A/C compressor, the relief
valve is serviced as a part of the compressor mani-
fold.

DIAGNOSIS AND TESTING

A/C COMPRESSOR NOISE

When investigating an A/C system related noise,
you must first know the conditions under which the
noise occurs. These conditions include: weather, vehi-
cle speed, transmission in gear or neutral, engine
speed, engine temperature, and any other special
conditions. Noises that develop during A/C operation
can often be misleading. For example: What sounds
like a failed front main bearing or connecting rod,
may be caused by loose bolts, nuts, mounting brack-
ets, or a loose A/C clutch assembly.
NOTE: Prior to a vehicle being removed from ser-
vice or stored for more than two weeks, the A/C
compressor should be operated to ensure adequate
refrigerant oil distribution throughout the system
components. Turn on the A/C for a minimum of five
minutes with outside air and the highest blower
speed selected.
Drive belts are speed sensitive. At different engine
speeds and depending upon belt tension, belts can
develop noises that are mistaken for an A/C compres-
sor noise. Improper belt tension can cause a mislead-
ing noise when the A/C clutch is engaged, which may
not occur when the A/C 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. Switch the
A/C compressor on and off several times to clearly
identify the compressor noise. Listen to the A/C com-
pressor 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 hard-
ware and retighten. Tighten the A/C clutch mounting
bolt. 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 CON-
JR