A/C System - Manual Supplement

BULLETIN NUMBER
SB93-12-001

ISSUE DATE
May 1993

GROUP
Heating & Air Conditioning

R-134A A/C WORKSHOP MANUAL SUPPLEMENT

AFFECTED VEHICLES

1993 Trooper (UX), Amigo (TC), Pick-up (TF) and Rodeo (UC) models.

SERVICE INFORMATION

The 1993 R-134a A/C Workshop Manual Supplement (part No. 2-90993-993-2) is included. Use this Supplement along with the 1993 Workshop Manuals for affected vehicles.








Affected vehicles may be equipped with either R-134a or R-12 A/C systems. Only a visual inspection of the vehicle can confirm which type A/C system is installed. All Isuzu vehicles equipped with R-134a A/C systems have a caution plate on the right side of the engine room firewall (Figure 1). R-134a system components are labeled "USE FOR R134a" (Figure 2).

R-134a systems differ from R-12 A/C systems in many ways:

- Refrigerant type and quantity
- Lubricant type and quantity
- Condenser, receiver/drier, service fittings, piping and hose design
- Seal/O-ring material
- Compressor model and lubricant
- Pressure switch settings

Service parts, equipment, refrigerant and oil for R-134a systems are NOT INTERCHANGEABLE with those for R-12 systems. R-134a systems use only PAG (polyalkylene glycol) oil as compressor lubricant. PAG oil must never be mixed with mineral-based lubricants used in R-12 systems; different grades of PAG oil must never be mixed.

Because of the incompatibility between R-134a and R-12, service equipment dedicated to R-134a use is required, to prevent cross-contamination during servicing. The following R-134a-dedicated equipment is required:

- Manifold gauge set (new coupling design and bose material)
- Recover/recyling station or evacuation pump
- Electronic leak detector (calibrated for R-134a)
- Accurate charging scale/station

SERVICE PROCEDURE

When servicing an R-134a A/C system, be sure to:

^ Refer to the Workshop Manual Supplement for procedures and specifications.

^ Use only service parts designated for R-134a systems.

^ When opening the A/C system, cap or plug all openings, to prevent dirt/moisture contamination. Due to PAG oil's high absorption rate, it will quickly become contaminated if the system is left open.

^ Use the sight glass only under specified conditions (ambient temperatures below 95 degrees F and 70% humidity).

^ Never mix PAG oil with R-12 system oil.

^ Never mix different grades of PAG oil

^ Properly dispose of any PAG oil remaining in its 40 ml container. Do not save it for later use.

PARTS INFORMATION

Part No. Description

2-90188-300-0 R-134a Compressor Lubricant (PAG Oil) (4-cylinder engine)

2-90188-301-0 R-134a Compressor Lubricant (PAG Oil) (3.2L V6 engine)

2-90222-320-0 R-134a Compressor Lubricant (PAG Oil) (3.1L V6 engine)