DIAGNOSIS AND TESTING
REFRIGERANT SYSTEM LEAKS
WARNING: R-134a service equipment or vehicle A/C system should not be pressure tested or leak tested
with compressed air. Mixture of air and R-134a can be combustible at elevated pressures. These mixtures
are potentially dangerous and may result in fire or explosion causing property damage, personal injury or
death.
Avoid breathing A/C refrigerant and lubricant vapor or mist. Exposure mayirritate eyes, nose and throat.
Use only approved service equipment meeting SAE requirements to discharge R-134a system. If accidental
system discharge occurs, ventilate work area before resuming service.
NOTE: If the A/C refrigerant system charge is empty or low, a leak in the A/C system is likely. Visually
inspect all A/C lines, fittings and components for an oily residue. Oil residue can be an indicator of an A/C
system leak location.
NOTE: The only way to correctly determine if the refrigerant system is fully charged with R-134a is to com-
pletely evacuate and recharge the A/C system.
Connect a suitable manifold gauge setand determine if the static A/C system pressure is above or below 345 kPa
(50 psi) (refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STANDARD PROCEDURE - REFRIGERANT
SYSTEM SERVICE EQUIPMENT). If less than 345 kPa (50 psi), proceed to SYSTEMEMPTY . If greater than 345
kPa (50 psi), go to SYSTEM LOW .
SYSTEM EMPTY
1. Evacuate the refrigerant system to the lowest degree of vacuum possible(approximately -88 kPa (- 26 in. Hg) or
greater vacuum) (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STANDARD PROCEDURE -
REFRIGERANT SYSTEM EVACUATE). Determine if the system holds a vacuum for 15 minutes. If vacuum is
held, a leak is probably not present. If system will not maintain vacuum level, proceed to Step 2.
2. Prepare and dispense 0.284 kilograms (10 ounces) of R-134a refrigerantinto the evacuated refrigerant system
(Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE) and proceed to Step 1 of the System Low procedure.
SYSTEM LOW
1. Position the vehicle in a wind-freework area. This will aid in detectingsmall leaks.
2. Operate the heating-A/C system with the engine at idle under the following conditions for at least five minutes.
Doors or windows open
Transmission in Park or Neutral with the parking brake set (depending on application)
A/C-heater controls set to outside air, full cool, panel mode, high blowerand with A/C compressor engaged
CAUTION: A leak detector only designed for R-12 refrigerant will not detect leaks in an R-134a refrigerant
system.
3. Shut the vehicle Off and wait 2-7 minutes. Then use an electronic leak detector that is designed to detect R-134a
refrigerant and search for leaks. Fittings, lines or components that appear to be oily usually indicate a refrigerant
leak. To inspect the A/C evaporator for leaks, insert the leak detector probe into the drain tube opening or an air
outlet. A dye for R-134a is available to aid in leak detection. Use only DaimlerChrysler approved refrigerant dye.
DIAGNOSIS AND TESTING
A/C COMPRESSOR
When investigating an A/C system related noise, you must first know the conditions under which the noise occurs.
These conditions include: weather, vehicle speed, transmission in gear or neutral, engine speed, engine tempera-
ture, and any other special conditions. Noises that develop during A/C operation can often be misleading. For exam-
ple: What sounds like a failed front engine bearing or connecting rod, may be caused by loose bolts, nuts, mounting
brackets or a loose compressor clutch assembly.
Drive belts are speed sensitive. At different engine speeds and dependingupon drive belt tension, drive belts can
develop noises that are mistaken for an A/C compressor noise. Improper drive belt tension can cause a misleading
noise when the compressor clutch is engaged, which may not occur when the compressor 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. Turn the A/C compressor
On and Off several times to clearly identify the compressor noise. Listen to the A/C compressor 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 hardware and retighten. Check thecompressor clutch retainer. 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 CONDITIONING/CONTROLS/
CLUTCH-A/C COMPRESSOR - INSTALLATION).
3. To duplicate high-ambient temperature conditions (high head pressure), restrict the air flow through the A/C con-
denser. Install a manifold gauge set or a scan tool to be certain that the discharge pressure does not exceed
2760 kPa (400 psi).
4. Check the refrigerant system plumbing for incorrect routing, rubbing or interference, which can cause unusual
noises. Also check the refrigerant lines and hoses for kinks or sharp bendsthat will restrict refrigerant flow, which
can cause noises (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - DESCRIPTION - REFRIGER-
ANT LINES).
5. If the noise is from opening and closing of the high pressure relief valve, recover, evacuate and recharge the
refrigerant system (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STANDARD PROCEDURE -
REFRIGERANT SYSTEM RECOVERY), (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STAN-
DARD PROCEDURE - REFRIGERANT SYSTEM EVACUATE) and (Refer to 24 - HEATING & AIR CONDITION-
ING/PLUMBING - STANDARD PROCEDURE - REFRIGERANT SYSTEM CHARGE). If the high pressure relief
valve still does not seat properly, replace the A/C compressor (Refer to 24- HEATING & AIR CONDITIONING/
PLUMBING/COMPRESSOR-A/C - REMOVAL).
6. If the noise is from liquid refrigerant slugging in the A/C suction line,replace the A/C accumulator (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING/ACCUMULATOR-A/C - REMOVAL) and check the refrigerant oil
level and the refrigerant system charge (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING/REFRIG-
ERANT OIL - STANDARD PROCEDURE - REFRIGERANT OIL LEVEL) (Refer to 24 - HEATING & AIR CON-
DITIONING/PLUMBING- STANDARD PROCEDURE - REFRIGERANT SYSTEM CHARGE).
7. If a slugging condition still exists after replacing the A/C accumulator, then replace the A/C compressor (Refer to
24 - HEATING & AIR CONDITIONING/PLUMBING/COMPRESSOR-A/C - REMOVAL) and repeat Step 1.
REMOVAL
3.7L/4.7L ENGINES
WARNING: Refer to the applicable warnings and cautions for this system before performing the following
operation (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - WARNINGS) and (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING - CAUTIONS). Failure to follow the warnings and cautions could result
in possible personal injury or death.
NOTE: The A/C compressor may be removed and repositioned without disconnecting the refrigerant lines or
discharging the refrigerant system. Discharging is not necessary if servicing the compressor clutch, clutch
coil, engine, engine cylinder head or the generator.
