DODGE RAM 1999 Service Repair Manual

panel assembly.
6) Connect vacuum source probe to each port of connector. See
Fig. 1. Record each vacuum gauge reading. Vacuum reading should be 8
in. Hg at each port.
NOTE: Brown (bi-level) vacuum circuit contains a restriction in
line. It takes longer to obtain correct vacuum reading on
this line.
7) If correct vacuum readings are obtained, replace faulty
A/C-heater control panel vacuum switch assembly. If proper vacuum
readings are not obtained, check appropriate vacuum circuit.
8) Start vacuum check by plugging vacuum hose at vacuum
actuator in suspect circuit. Recheck vacuum circuit by connecting
vacuum source probe to proper port.
9) If proper vacuum reading is now obtained, replace vacuum
actuator. If proper reading is not obtained, check vacuum hoses and
connections for leak. Repair or replace as required.
Fig. 1: Testing A/C-Heater System Vacuum Control Circuits
Courtesy of Chrysler Corp.
TROUBLE SHOOTING

Fig. 2: Blower Motor System Diagnosis (Except RWD Van)
Courtesy of Chrysler Corp.

Fig. 3: Blower Motor & Control System Diagnosis (RWD Van)
Courtesy of Chrysler Corp.

Fig. 4: Blower Motor Noise & Vibration Diagnosis
Courtesy of Chrysler Corp.

Fig. 5: A/C Compressor & Compressor Clutch Diagnosis (1 Of 2)
Courtesy of Chrysler Corp.

Fig. 6: A/C Compressor & Compressor Clutch Diagnosis (2 Of 2)
Courtesy of Chrysler Corp.

Fig. 7: A/C Diagnosis - Fixed Displacement Compressors
Courtesy of Chrysler Corp.


A/C S YSTE M G EN ER AL S ER VIC IN G
1999 D odge P ic ku p R 1500
1999 GENERAL SERVICING
A/C System General Servicing
All Models
USING R-134a REFRIGERANT
HANDLING/SAFETY PRECAUTIONS
1) Always work in a well-ventilated, clean area. Refrigerant
is colorless and invisible as a gas. Refrigerant is heavier than
oxygen and will displace oxygen in a confined area. Avoid breathing
refrigerant vapors. Exposure may irritate eyes, nose and throat.
2) Always wear eye protection when working around A/C system
and refrigerant. The system's high pressure can cause severe injury to
eyes and skin if a hose were to burst. If necessary, wear rubber
gloves or other protective clothing.
3) Refrigerant evaporates quickly when exposed to atmosphere,
freezing anything it contacts. If liquid refrigerant contacts eyes or
skin (frostbite), DO NOT rub eyes or skin. Immediately flush affected
area with cool water for 15 minutes and consult a doctor or hospital.
4) Never use R-134a in combination with compressed air for
leak testing. Pressurized R-134a in the presence of oxygen (air
concentrations greater than 60 percent by volume) may form a
combustible mixture. DO NOT introduce compressed air into R-134a
containers (full or empty), A/C system components, or service
equipment.
5) DO NOT expose A/C system components to high temperatures
(steam cleaning for example), as excessive heat will cause refrigerant\
system pressure to increase. Never expose refrigerant directly to open
flame. If refrigerant needs to be warmed, place bottom of refrigerant
tank in warm water. Water temperature MUST NOT exceed 125
F (52C).
CAUTION: When R-134a is exposed to an open flame, drawn into engine,
or detected with a Halide (propane) leak tester, a poisonous
gas is formed. Keep work areas well ventilated.
6) Use care when handling refrigerant containers. DO NOT
drop, strike, puncture, or incinerate containers. Use DOT 4BW or DOT
4BA approved refrigerant containers.
7) Never overfill refrigerant containers. The safe filling
level of a refrigerant container MUST NOT exceed 60\% of the
container's gross weight rating. Store refrigerant containers at
temperatures less than 125
F (52C).
8) R-134a refrigerant is sold and stored in 30- or 50-pound
Light Blue containers, while Freon (R-12) is stored in White colored
containers.
9) Refrigerant R-12 and R-134a must never be mixed, as they
and their desiccants and lubricants are not compatible. If the
refrigerants are mixed, system cross-contamination or A/C system
component failure may occur. Always use separate servicing and
refrigerant recovery/recycling equipment.
10) Read and follow equipment manufacturer's instructions for
all service equipment to be used. The Material Safety Data Sheet
(MSDS), provided by refrigerant manufacturer/supplier, contains
valuable information regarding the safe handling of refrigerants.
IDENTIFYING R-134a SYSTEMS & COMPONENTS

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