G 1500 1/2 Ton Van V8-350 5.7L (1986)
Technical Service Bulletin # 88T931B
Date: 880501
A/C - Performance Improvement
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
Condenser Replacement
Replacement condenser assemblies are direct replacements for the existing condensers and are used as follows:
1985-1986 On all Engines, 52450904 condenser replaces 3057628 condenser.
1987-1988 52450903 condenser replaces 3091057 condenser on LB4 engines (gas V6, 4.3L); L03 engines (gas V8 5.0L); L05 engines (gas V8, 5.7L).
52450904 condenser replaces 3057628 condenser on LH6 engines (diesel 8 cylinder, 6.2L); LL4 engines (diesel 8 cylinder 6.2L heavy duty); and LT9
engines (gas V8 heavy duty 5.7L (350).
SERVICE PROCEDURES
I.
CONDENSER REPLACEMENT
Follow procedure described in Section 1B of the G Van Service Manual.
Labor Op D3140 Time:
.7 hr Gas .6 hr Diesel
Add:
.3 hr with auxiliary oil cooler
Add:
.5 hr - discharge/ charge A/C system