INSUFFICIENT A/C COOLING DIAGNOSIS AND REPAIR
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
II. HEATER WATER BY-PASS VALVE INSTALLATION (Figure No. 1)
a) Drain radiator
b) Remove air cleaner inlet tube.
c) Remove heater bose (1) and discard
d) Remove beater bose (2) from heater core and install at inlet connection of heater waterby-passvalve (3) and tighten hose clamp (4).
NOTICE: All hose clamps removed during valve installation sbould be discarded and replaced with new hose clamps.
e) Install new 5/8" performed heater hose (5) from heater by-pass valve to heater core (cut to length).
f) Install new 3/4" performed heater hose (6) from heater water by-pass valve to heater core (cut to length).
g) Install new 3/4" preformed heater outlet hose (1) from heater water by-pass valve to radiator (cut to length).
h) Wrap plastic wiring harness around heater hose (1) to eliminate kinking and chafing.
i) Band strap beater hose (2) to heater hose (1) as shown so hoses do not rub edge of radiator shroud.
j) Tighten all hose clamps.
IIA. VACUUM VALVE INSTALLATION (Figures No. 2,3, and 4)
a) Drill a 7/32" diameter hole in dash wall next to hood latch cable (Figure No. 2) and deburr edges of hole.
b) Install vacuum hose (l) on heater water by-pass valve (2) and route with A/C barness (3) to hole in dash. Band strap (4) hose to harness as shown. Apply sealer around hose as necessary to seal.
c) Remove engine cover and instrument panel lower extension for next step.
d) Remove instrument cluster trim plate.
e) Remove HVAC control assembly (Figure No. 3) and slide assembly out of dash sufficiently to gain access to rear of the unit.
f) Install vacuum valve on heater control assembly (Figure No. 3). Slide one mounting ear on valve under tbe slot on control assembly. Install and tighten screw in opposite ear. (Note: Pin on bottom of vacuum valve must fit into slot on the temperature control arm.)
g) Locate gray colored vacuum source line at A/C control assembly (Figure No. 4).
h) Cut gray vacuum source line and insert vacuum tee (1) (Figure No. 4). Attach 6" long vacuum line from vacuum tee to vacuum valve inlet port 1. Attach vacuum bose from heater valve to vacuum valve outlet port 2 (Figure No. 4).
Notice: Part numbers are identified on valve.
i) Reinstall control assembly in dash.
j) Reinstall instrument cluster trim plate.
k) Reinstall engine cover and instrument panel lower extension.
l) Refill radiator with coolant.
m) Run engine and check for coolant leaks.
n) Place temperature control arm in high heat position, check the position of the lever on the heater water by-pass valve. It should be in the extended position. Place control selector in the full cold position and recheck valve. Lever sbould be in the retracted position.
o) Shut off engine and reinstall air cleaner inlet tube.
Labor Op: T7535 Labor Time: 1.3 hrs.
III. AIR INLET RECIRCULATING DOOR REPLACEMENT
A. Removal
1. Drain radiator
2. Disconnect battery ground cable.
3. Remove engine cover.
4. Remove steering column filler panel and remove panel.
5. Remove steering column support bracket and allow column to drop for clearance.
6. Remove righthand sun visor.
7. Remove righthand pillar post molding (if so equipped).
8. Remove upper instrument panel support bracket.
9. Raise and support right side on instrument panel.
10. Remove R.H. beater duct.
11. Remove L.H. heater duct.
12. Remove recirculating air door actuator. Remove and rotate actuator to unhook actuator arm from valve.
13. Disconnect 2 heater cables and clamps and 4 vacuum hoses to heater and recirculating door actuators.
14. Remove front heater valve actuators and remove actuators.
15. Remove defroster duct to heater and lift duct.
16. Loosen clamps and disconnect heater inlet and outlet hoses.
17. Remove heater to cowl and remove heater from vehicle.
18. Remove air recirculating door to cowl.
19. Remove door and discard. Retain gasket.
B. Installation
1. Remove actuator from new door.
2. Install new door and gasket. Secure with 6 screws.
3. Reverse removal procedure.
Labor Op: T75 40 Labor Time: 3.3 hrs.
IV. EVAPORATOR CORE CASE SEAL REPLACEMENT (Figure No. 5)
a) Follow evaporator core replacement procedure found in Section 1B of the Service Manual.
Notice: Complete evaporator core removal is not required. Removal of the core case assembly will allow access to the seal.
Labor Op T7545 Labor Time: 1.0 hrs. Add .5 hrs to discharge/charge A/C
Labor Op T7550 LaborTime: 5.8 hrs to perform all of the above procedures
PARTS INFORMATION
Part Number Description Quantity ------ ----------- -------- 7897420 Vacuum Control Valve 1
14044414 Heater Water By-Pass 1 Valve
52450903 Condenser Assembly (1987- 1 1988) 4.3L5.0L and 5.7L
52450931 Air Inlet and Recirculating 1 Door Assembly
3053203 "O" Ring, Condenser Inlet 1
309311 "O" Ring, Condenser Outlet 1
482424 Pre-formed Heater Hose, 2 3/4 Inch
14036206 Pre-formed Heater hose, 5/8 1 Inch (Cut to Length)
3035292 Seal, Evaporator Core 1 Screw
11509374 Screw 1
52450904 Condenser Assembly - 1 1985-86 All Engines,1987- 88 6.2L Diesel and 5.7L Heavy Duty LT9 Engines
No Part Numbers (Procure Locally)
Hose, 3/32 Inch ID Vacuum 1 (72 Inch) 1/8 x 1/8 x 1/8 OD Tee, 1 Vacuum Hose Hose Clamp (#8 1/2 Inch - 1 7 inch)
Bandstrap (Tie Wrap) 8 Inch 5
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.
