A/C System - Poor Performance
87isuzu03BULLETIN NUMBER ISSUE DATE GROUP
SB87-12-004 September 15, 1987 HEATING & AIR CONDITIONING
P'UP (KB) AND TROOPER II (KT) AIR CONDITIONING FREEZING UP
VEHICLES AFFECTED
1986-87 P'UP (KB) and Trooper II (KT) models with American Isuzu Motors Inc. air conditioning kit.
SERVICE INFORMATION
Under extremely humid, high temperature conditions, some affected models may experience poor air conditioning performance due to evaporator freezeup. If testing of the evaporator thermostat shows that it operates correctly, re-routing the thermostat capillary tube can correct the problem.
This Service Bulletin describes the procedures for testing A/C evaporator thermostat performance and for re-routing the thermostat capillary tube.
FIGURE 1:
SERVICE PROCEDURE
1. Discharge the A/C system.
2. Remove evaporator assembly from vehicle.
3. Remove thermostat from evaporator assembly (Figure 1).
4. Test thermostat performance by running the following test:
a. Immerse the end of the thermostat capillary tube in a small pan filled with ice water.
b. Check for continuity within the following temperature ranges:
Cut-off 1.5-0.5 C~ (35-33 F~)
Cut-in 2.5-5.0 C~ (37-41 F~)
c. If cut-off or cut-in temperature is too low or too high, replace the thermostat.
FIGURE 2:
5. If thermostat operates correctly during the continuity test, reinstall it in a new position in the evaporator (Figure 2).
6. Reinstall evaporator assembly as outlined in the appropriate Workshop Manual.
7. Evacuate and recharge A/C system as described in the appropriate Workshop Manual.
FLAT RATE MANUAL UPDATE INFORMATION