1999 DODGE RAM Service Repair Manual

To prevent refrigerant cross-contamination, use following
methods to identify R-134a based systems and components.
Fittings & "O" Rings
All R-134a based A/C systems use 1/2" - 16 ACME threaded
fittings (identifiable by square threads) and quick-connect service
ports. See Fig. 1.
Fig. 1: Identifying R-134a Service Ports
Courtesy of chrysler corp.
Underhood A/C Specification Labels
Most R-134a based systems will be identified through the use

of underhood labels with R-134a refrigerant clearly printed on labels.
See Fig. 2 . The underhood label used on Ford Motor Co. vehicles is
Yellow. See Fig. 3. Most manufacturers will identify refrigerant type
with labels affixed to compressor. Before servicing an A/C system,
always determine which refrigerant is being used.
Fig. 2: Underhood Refrigerant Identification Labels (Typical)
Courtesy of chrysler corp.
Fig. 3: Underhood Refrigerant Identification Label (Typical)
Courtesy of ford motor co.
REFRIGERANT OILS

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)









\









\









\









\









\









\









\








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.









\









\









\









\









\









\









\








SERVICE VALVE LOCATIONS (TRUCKS & VANS)









\









\









\









\









\









\









\








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.









\









\









\









\









\









\









\








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