Dodge RAM TRUCK 1500 1995 Service Manual page 1672

en HEATING AND AIR CONDITIONING 24 - 3
switch contacts open and close turning the. compres­
sor clutch on and off. This regulates the system pres­
sure. Lower ambient temperatures, below
approximately -1°C (30°F) during cold weather will
also open the switch contacts. This is due to the pres­
sure/temperature relationship of the refrigerant in
the system.
CONDENSER^ The condenser is located in front of
the engine radiator. Its function is to cool the hot
high pressure refrigerant gas. This causes it to con­
dense into high pressure liquid refrigerant.
EVAPORATOR COIL: The coil is located in the
A/C housing. Its function is to remove heat and de-
humidify the air before it enters the vehicle.
FIXED ORIFICE TUBE: The orifice tube is lo­
cated in the outlet line of the condenser. The inlet
and outlet ends have a screen to filter the refriger­
ant. O-rings on the orifice tube body prevent the re­
frigerant from bypassing the orifice. The orifice tube
is used to meter the flow of liquid refrigerant into the
evaporator core.
HIGH PRESSURE RELIEF VALVE: The valve is
located on the compressor manifold. The valve is
used to prevent excessive pressure build up. This
prevents damage to the compressor and other system
components.
HIGH-PRESSURE CUT-OUT SWITCH: The
switch is located on the discharge line.The switch is
wired in series with compressor clutch. The switch
interrupts power to the compressor clutch, when ex­
cessive pressure is present.
REFRIGERANT LINES: The lines are used to
carry the refrigerant between the various system
components. The barrier hose design is used for the
air conditioning system on this vehicle. The ends of
the A/C hoses are made from light-weight aluminum
and use new braze-less fittings.
SPRING LOCK COUPLER: The coupler is used
to attach A/C lines and other components. The cou­
pling is held together by a garter spring inside a cir­
cular cage. When the coupling is connected together,
the flared end of the female fitting slips behind the
garter spring inside the cage of the male fitting. The
garter spring and cage prevent the flared end of the
female fitting from pulling out of the cage. O-rings
are used to seal the coupling. These O-rings are com­
patible with R-134a refrigerant and must be replaced
with O-rings made of the same material.
SERVICE PORTS: The low and high pressure ser­
vice ports are attached to the refrigerant lines. These
ports are used to attach A/C gauges. After servicing
the refrigerant system, always install service port
caps.
REFRIGERANT
This vehicle uses a new type of refrigerant called
R-134a. It is a non-toxic, non-flammable, clear color­
less liquified gas.
R-134a refrigerant is not compatible with R-12 re­
frigerant in an air conditioning system. Even a small
amount of R-12 in a R-134a system will cause com­
pressor failure, refrigerant oil sludge or poor air con­
ditioning system performance.
REFRIGERANT OIL
The oil used in the SD7H15 compressor is a poly-
alkylene glycol synthetic oil SP-20 PAG. Only refrig­
erant oil of the same type should be used to service
the system. Do not use any other oil. The oil con­
tainer should be kept tightly capped until it is ready
for use and then capped after use to prevent contam­
ination. Refrigerant oil will quickly absorb any mois­
ture it comes in contact with. *
REFRIGERANT EQUIPMENT
WARNING: E Y E PROTECTION MUST
BE
U S E D
W H E N SERVICING AN AIR CONDITIONING R E F R I G ­
ERANT S Y S T E M . TURN OFF (ROTATE C L O C K W I S E )
ALL VALVES ON THE EQUIPMENT BEING U S E D
B E F O R E PROCEEDING WITH THIS OPERATION.
P E R S O N N E L INJURY CAN RESULT.
Chrysler Corporation recommends a (R-134a) recy­
cling device that meets SAE standard J2210 be used
when servicing the refrigerant system. Contact an
automotive service equipment supplier for refrigerant
recycling equipment that is available in your area.
Refer to the operating instructions provided with the
recycling equipment for proper operation.
MANIFOLD GAUGE SET
A R-134a manifold gauge set (Fig. 5) may be
needed in conjunction with the charging and or re­
covery/recycling device. The service hoses on the
gauge set being used should have manual (turn
wheel) or automatic back flow valves at the service
port connector ends. 1 This will prevent refrigerant
from being release into the atmosphere.
LOW PRESSURE GAUGE HOSE
The low pressure hose (BLUE with BLACK STRIP)
attaches to the suction service port. This port is lo­
cated at the right front of the engine compartment in
the condenser-to-evaporator line.
HIGH PRESSURE GAUGE HOSE
The high pressure hose (RED with BLACK STRIP)
attaches to the discharge service port. This port is lo­
cated on the compressor plumbing or manifold. -