Evaporator Core: Service and Repair

Fig. 45 Wiring Harness & Relays. 1989-90 Oldsmobile, Pontiac & 1990 Buick:

Fig. 46 Blower Module Assembly. 1989-90 Oldsmobile, Pontiac & 1990 Buick:

Brazed fittings are used on the condenser and evaporator. These fittings cannot be turned. It is important that the service technician recognize which fitting is to be turned and use backup wrenches. The brazed fitting that should not be turned is always the same color as the pipe it is brazed to.
1. Disconnect battery ground cable.
2. Discharge A/C system, then remove engine compartment rear sight shield. Refer to Engine Cover Replacement Service and Repair.
3. Disconnect four electrical connections and remove relay bracket assembly, Fig. 45.
4. Disconnect accumulator to condenser hose.
5. Disconnect electrical connector from pressure cycling switch, then the evaporator outlet line from accumulator.
6. Remove accumulator bracket and accumulator, cap accumulator openings.
7. Disconnect tube from condenser to evaporator, then disconnect power steering pump and position aside.
8. Remove vacuum tank and blower motor.
9. Remove exhaust manifold heat shield, then drain engine coolant.
10. Disconnect heater hoses from heater core, then remove blower motor resistor.
11. Disconnect evaporator outlet line and support bracket.
12. Remove right side sound insulator from under instrument panel.
13. Remove floor air outlet duct, then five lower evaporator and blower module attaching bolts, Fig. 46.
14. Raise and support vehicle, then remove three lower evaporator and blower module attaching bolts.
15. Cut rubber blower barrier along guide line, then lower vehicle.
16. Remove seven upper evaporator and blower module attaching bolts.
17. Finish cutting rubber barrier along guide lines.
18. Remove screws from evaporator cover, then evaporator from module.
19. Reverse procedure to install, sealing rubber barrier with strip calk where it had been cut.