DODGE RAM 1999 Service Repair Manual

Refrigerant R-12 based systems use mineral oil, while R-134a
systems use synthetic Polyalkylene Glycol (PAG) oils. Using a mineral
oil based lubricant with R-134a will result in A/C compressor failure
due to lack of proper lubrication.
Following are the most common R-134a refrigerant oils used by
most domestic vehicles:
Chrysler Corp., Eagle & Jeep
Use ND-8 PAG oil, SUN PAG 56 oil, SP-10 PAG Oil, or SP-20 PAG
oil.
Ford Motor Co.
Use YN-12B or YN-12C PAG Refrigerant Oil (specification WSH-
M1C231-B) or SP-20 PAG Oil (specification WST-M1C231-B2).
General Motors
On all models except Saturn, use PAG Refrigerant Oil (Part
No. 12345923). On Saturn, use Saturn PAG refrigerant oil.
NOTE: PAG oil absorbs moisture very rapidly, 2.3-5.6 percent by
weight as compared to a mineral oil absorption rate of .005
percent by weight.
NOTE: Use ONLY the specified oil for the appropriate system or A/C
compressor. Always check the underhood A/C specification
label or A/C compressor label before adding refrigerant oil
to A/C system.
SYSTEM SERVICE VALVES
SCHRADER-TYPE VALVES
NOTE: Although similar in construction and operation to a tire
valve, NEVER replace a Schrader-type valve with a tire
valve.
Schrader valve is similar in construction and operation to a
tire valve. See Fig. 4. When a test gauge hose is attached (hose has
built-in valve core depressor), Schrader stem is pushed inward to the
open position and allows system pressure to reach the gauge.
If test hose being used does not have a built-in core
depressor, an adapter must be used. Never attach hoses or adapters to
a Schrader valve unless it is first connected to manifold gauge set.
Fig. 4: Schrader Service Valve (Compressor Location Shown)
SPECIAL VALVE CONNECTORS
On some General Motors models, thread size on high-side

service valve (3/8" - 24 threads) is different from thread size on
low-side service valve (7/16" - 20 threads). Special adapters are
required to make this connection. See Fig. 5. These adapters are
available in 45-degree and 90-degree angles in addition to straight-
fixed and flexible adapters.
Fig. 5: Flexible High Side Adapter
R-134a SERVICE VALVES/PORTS
All vehicles with R-134a refrigerant use quick-disconnect
service valves/ports. All R-134a systems use quick-disconnect fittings
with sealing caps that thread into inside of service port instead of
onto outside of service port.
The high side uses a large service port, and the low side
uses a small service port. See Fig. 1. The R-134a service ports have
internal metric threads to help prevent the accidental connection of
R-12 servicing equipment.
There are 2 types of quick-disconnect service couplings which
can be used on R-134a systems. One type of service coupling depresses
service port valve when connection is made. The other type connects
onto service port but will not depress service port valve until a knob
is rotated. See Fig. 6.
Fig. 6: R-134a Service Couplings
Courtesy of chrysler corp.

SERVICE VALVE LOCATIONS
For service valve locations, see SERVICE VALVE LOCATIONS
(CARS) or SERVICE VALVE LOCATIONS (TRUCKS & VANS) table.
SERVICE VALVE LOCATIONS (CARS)









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Vehicle High Low
Chrysler Corp.
Avenger & Sebring Coupe .................... ( 1) ........... ( 2)
Concorde, Intrepid, LHS & 300M
2.7L ...................................... ( 3) ........... ( 4)
3.2L & 3.5L ............................... ( 5) ........... ( 6)
Breeze, Cirrus & Stratus ................... ( 7) ........... ( 4)
Neon ....................................... ( 7) ........... ( 4)
Sebring Convertible ........................ ( 7) ........... ( 4)
Ford Motor Co.
Continental ................................ ( 9) .......... ( 10)
Contour, Cougar & Mystique
2.0L Engine ............................... ( 7) .......... ( 11)
2.5L Engine ............................... ( 7) .......... ( 12)
Crown Victoria, Grand Marquis & Town Car ... ( 7) .......... ( 13)
Escort & Tracer ............................ ( 14) ......... ( 10)
Mustang .................................... ( 7) .......... ( 12)
Sable & Taurus ............................. ( 8) .......... ( 11)
General Motors
"C" Body ................................... ( 3) .......... ( 15)
"E" & "K" Bodies ........................... ( 3) .......... ( 15)
"F" Body ................................... ( 9) ........... ( 4)
"G" Body ................................... ( 3) .......... ( 15)
"H" Body ................................... ( 7) .......... ( 12)
"J" Body ................................... ( 7) .......... ( 12)
"M" Body ................................... ( 9) ........... ( 4)
"N" Body ................................... ( 9) ........... ( 4)
"S" Body ................................... ( 9) ........... ( 4)
"V" Body ................................... ( 9) ........... ( 4)
"W" Body ................................... ( 9) ........... ( 4)
"Y" Body ................................... ( 3) .......... ( 12)
"Z" Body ................................... ( 7) .......... ( 15)
( 1) - On high-side liquid line, between receiver-drier and evaporator.
( 2) - On low-side hose between evaporator and compressor.
( 3) - On high-side liquid line.
( 4) - On low-side suction line.
( 5) - On top of compressor manifold.
( 6) - On compressor manifold, closest to compressor clutch.
( 7) - On high-side line, between compressor and condenser.
( 8) - On extension of high-side line, between condenser and
evaporator.
( 9) - On high-side line (or extension), near condenser.
( 10 ) - On low-side line (or extension), near accumulator.
( 11 ) - On low-side line, between the evaporator and
accumulator/receiver-drier.
( 12 ) - On low-side line, between acumulator/receiver-dryer and
compressor.
( 13 ) - On acumulator/receiver-drier.
( 14 ) - On high-side line, near condenser.
( 15 ) - On low-side line, between orifice tube and evaporator.









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SERVICE VALVE LOCATIONS (TRUCKS & VANS)









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Vehicle High Low
Chrysler Corp.
Caravan, Town & Country, & Voyager ......... (1) ........... ( 2)
Dakota ..................................... ( 3) ........... ( 4)
Durango .................................... ( 3) ........... ( 4)
Ram Pickup ................................. ( 3) ........... ( 5)
Ram Van/Wagon .............................. ( 6) ........... ( 7)
Ford Motor Co.
"E" Series ................................. ( 4) ........... ( 8)
Explorer, Mountaineer & Ranger ............. ( 6) ........... ( 9)
F150, F250LD, Expedition & Navigator ....... ( 6) ........... ( 9)
F250HD, F350 & Super Duty .................. ( 6) ........... ( 5)
Villager ................................... ( 10) .......... ( 5)
Windstar ................................... ( 11) .......... ( 9)
General Motors
"C" & "K" Series ........................... ( 4) ........... ( 9)
"G" Series ................................. ( 12) .......... ( 9)
"J" Series ................................. ( 9) .......... ( 13)
"L" & "M" Series ........................... ( 12) .......... ( 5)
"P" Series ................................. ( 14) ......... ( 15)
"S" & "T" Serie ............................ ( 16) .......... ( 9)
"U" Series ................................. ( 1) ........... ( 5)
Jeep
Cherokee ................................... ( 6) .......... ( 17)
Grand Cherokee ............................. ( 18) ......... ( 14)
Wrangler ................................... ( 4) .......... ( 14)
( 1) - On high-side line, near right frame rail. See Fig. 7.
( 2) - On low-side line, near compressor. See Fig. 7.
( 3) - On high-side line, between condenser and evaporator, near front
of engine compartment.
( 4) - On compressor manifold.
( 5) - On low-side line, near accumulator.
( 6) - On high-side line, between compressor and condenser, near front
of engine compartment.
( 7) - On low-side line extension, near receiver-drier, at front of
engine compartment.
( 8) - On low-side line from accumulator, near windshield washer
reservoir.
( 9) - On accumulator/receiver-drier.
( 10 ) - On high-side line extension from compressor.
( 11 ) - On high-side line, between compressor and condenser, near
accumulator. See Fig. 8.
( 12 ) - On high-side line between evaporator and condenser, near
evaporator.
( 13 ) - On low-side (suction) line, near compressor.
( 14 ) - On high-side inlet line, at evaporator.
( 15 ) - On low-side outlet line, at evaporator.
( 16 ) - On high-side line.
( 17 ) - On low-side (suction) line, between accumulator outlet and
compressor.
( 18 ) - On high-side (liquid) line, near evaporator inlet, at rear of
engine compartment.









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Fig. 7: Locating Service Valves (Caravan, Town & Country, & Voyager)
Courtesy of chrysler corp.

Fig. 8: Locating Service Valves (Windstar)
Courtesy of ford motor co.
SERVICE EQUIPMENT

Because R-134a is not interchangeable with R-12, separate
sets of hoses, gauges, and recovery/recycling equipment are required
to service vehicles. This is necessary to avoid cross-contamination
and damaging system.
All equipment used to service systems using R-134a must meet
SAE standard J2210. The service hoses on the manifold gauge set must
have manual (turn wheel) or automatic back-flow valves at the service
port connector ends. This will prevent refrigerant from being released
into the atmosphere.
For identification purposes, R-134a service hoses must have a
Black stripe along their length and be clearly labeled SAE J2196/134a.
The low pressure test hose is Blue with a Black stripe. The high-side
test hose is Red with a Black stripe. The center test hose is Yellow,
or White, with a Black stripe.
NOTE: Refrigerant R-12 service hoses will ONLY be labeled SAE
J2196.
All R-134a manifold gauge sets can be identified by one or
all of the following:
* Labeled FOR USE WITH R-134a on set.
* Labeled HFC-134 or R-134a on gauge face.
* Light Blue color on gauge face. In addition,
pressure/temperature scales on R-134a gauge sets are
different from R-12 manifold gauge sets.
MANIFOLD GAUGE SET
A manifold gauge set is used to determine the system's high-
side and low-side pressures, correct refrigerant charge, and operating
efficiency. High (discharge) and low (suction) pressures must be
compared to determine system operation. Manifold gauge sets for the 2
refrigerant types are basically the same except for fittings at ends
of hoses. Fittings are different to ensure connection only to
appropriate refrigerant system.
Low-Side Gauge
Low-side gauge, which may have a Blue identifying feature, is
used to measure low-side (suction) pressure. Low-side gauge is also
called a compound gauge because it can measure pressure and vacuum.
Pressure scale ranges from 0 to 150 psi; vacuum scale ranges from 0 to
30 in. Hg.
High-Side Gauge
High-side gauge, which may have a Red identifying feature, is
used to measure high-side (discharge) pressure. Gauge scale ranges
from 0 to 500 psi.
CONNECTING GAUGE SET
NOTE: R-134a quick disconnect service couplings are connected in
the same sequence as Schrader-type service valves.
Schrader-Type Valves
1) Put on safety goggles, and cover vehicle's fender. Slowly
remove protective caps from Schrader valves to check for leaky valves.
CAUTION: Ensure hand valves on manifold gauge set and the hose-end
shutoff valves are closed before attaching test hoses to
Schrader valves.

2) Ensure service hoses are equipped with valve core
depressor to match Schrader valve. If not, install special adapters
for this purpose. If the high-side service hose connector will not fit
on high-side Schrader valve, a special adapter must be used. See
SPECIAL VALVE CONNECTORS.
3) Ensure both manifold gauge set hand valves are closed.
Connect low-side service hose to low-side (suction) service valve, and\
finger tighten connections. Connect high-side service hose to high-
side (discharge) service valve, and finger-tighten connections.
NOTE: After test gauges are installed, test hoses must be purged of
all air before proceeding with testing.
PURGING TEST HOSES
1) Ensure high-side and low-side hoses are properly connected
to service valves, and all hose connections are tight. Place a clean
shop towel over end of center service hose.
2) Purge high-side test hose by opening hand valve on high-
side gauge for 3-5 seconds. This allows the system's refrigerant to
force air through test hoses and out of center service hose into the
shop towel. Immediately close high-side gauge hand valve.
3) Purge low-side test hose in the same manner using hand
valve of low-side gauge. Close hand valve after 3-5 seconds. Purging
of test hoses is now complete, and system is ready for testing.
NOTE: If manifold gauge set is to be used in conjunction with
refrigerant recovery/recycling equipment, use instructions
provided with the recovery/recycling equipment to properly
purge test hoses.
STABILIZING A/C SYSTEM
1) Once manifold gauge set is attached to system and test
hoses have been purged, the system is ready for testing. Place all
test hoses, gauge set and other equipment away from all moving parts
of engine.
2) Start engine, and turn A/C controls to maximum cooling
position (full cold or MAX A/C). Set blower on high speed. Open doors
and/or windows. Operate system for 5-10 minutes. System should now be
stabilized and ready for test readings.
PRESSURE-TEMPERATURE RELATIONSHIP
A refrigerant, when confined in an enclosed space, increases
in pressure as the temperature increases. Conversely, if the
temperature is lowered, the pressure also decreases.
Depending on temperature, a corresponding pressure will exist
in such an enclosed space. For example, at 70
F (21.1C) a gauge will
indicate about 71.0 psi (5.0 kg/cm). The R-134a PRESSURE- TEMPERATURE
RELATIONSHIP table shows this relationship.
R-134a PRESSURE-TEMPERATURE RELATIONSHIP









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Temperature F (C) ( 1) psi (kg/cm)
20 (-6.7) ................................................. 18 (1.3\
)
30 (-1.1) ................................................. 26 (1.8\
)
40 (4.4) .................................................. 35 (2.5\
)
50 (10.0) ................................................. 45 (3.2\
)
60 (15.6) ................................................. 57 (4.0\
)

70 (21.1) ................................................. 71 (5.0\
)
80 (26.7) ................................................. 87 (6.1\
)
90 (32.2) ................................................ 104 (7.3\
)
100 (37.8) ............................................... 124 (8.7\
)
110 (43.3) .............................................. 147 (10.3\
)
120 (48.9) .............................................. 171 (12.0\
)
130 (54.4) .............................................. 199 (14.0\
)
140 (60.0) .............................................. 229 (16.1\
)
150 (65.6) .............................................. 263 (18.5\
)
160 (71.1) .............................................. 300 (21.1\
)
(1) - Pressure readings are provided as a general guideline and may
not represent actual readings.









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PRESSURE GAUGE READINGS
The pressure gauge readings shown represent an expansion
valve type system using a Nippondenso 10-cylinder compressor. See
Figs. 9 -17. Gauge indications will vary depending on system
configuration and compressor application.
Temperature and humidity, as well as other factors, affect
pressure gauge readings. Compared to R-12 systems, pressure readings
on R-134a systems are generally lower for low-side pressure and higher
for high-side pressure. Pressure gauge readings should be used only as
a guide.
NOTE: For additional information, see latest MITCHELL AUTOMOTIVE
AIR CONDITIONING BASIC SERVICE TRAINING MANUAL.
Fig. 9: Normally Functioning R-134a A/C System

Fig. 10: Some Moisture In R-134a System
Fig. 11: Low R-134a Charge