A/C - Performance Improvement: Overview

88chevy24

GMC NUMBER: 88-T-93

GROUP: 1B - Air Conditioning

DATE: May, 1988


CORPORATE
NUMBER: 861202
SUBJECT: G VAN A/C PERFORMANCE IMPROVEMENT

MODELS: 1985-1988 G VANS EQUIPPED WITH RPO C60 AND C69 AIR CONDITIONING
Some owners of 1985-1988 G Van models may comment about insufficient cooling from the A/C system. If following the diagnostics found in the Light Duty Service Manual, Section 1B, does not address this condition, one or more of the following additional procedures can be performed at the dealer's discretion to enhance the A/C performance.


1. Replace current A/C condenser with a larger fin area condenser. (This can affect outlet air temperature performance by 2-3 degrees F.)

2. Install a heater water by-pass valve in the heater inlet hose. (This can affect outlet air temperature performance by up to 5 degrees F.) This valve prevents hot engine coolant from circulating through the heater core while the A/C is being used.

3. Replace air inlet and recirculating door assembly with a new door with improved sealing. (This can affect outlet air temperature performance by 3-5 degrees F.) The new door reduces the amount of outside air that has to be cooled while in the max A/C position.

4. Replace case seal on evaporator core case. If accumulator can be moved by light hand pressure, this may indicate an undersized case seal. An undersized seal will allow air to bypass the evaporator and not be cooled.
Notice: Vehicles built after the following VIN breakpoints (B.P.) are equipped with the new condensers and the air inlet recirculating door:

Engine Part No. Part Name VIN B.P.
4.3, 5.0, 52450903 Condenser GMC J4507802

5.7 GMC J7518794


LH6 (6.2L 52450904 Condenser GMC J4509065
Diesel) GMC J7518794
LL4 (6.2L Diesel) LT9 (5.7L Gas)

ALL 52450931 Air Inlet GMC J4507847
Recirculating GMC J7518794 Door