A/C - Insufficient Cooling in High Temperatures
90chevy23GMC NUMBER: 90-1B-84
GROUP: 1B Air Conditioning
DATE: August, 1990
CORPORATE
NUMBER: 061203
INSUFFICIENT COOLING IN HIGH AMBIENT TEMPERATURES SUBJECT:
MODELS: 1988-90 S/T TRUCKS WITH AIR CONDITIONING (RPO C60)
Some of the S/T model trucks from 1988 through 1990 with air conditioning may receive comments of insufficient cooling in high ambient temperatures. To address this condition a water shut off valve which operates during Max A/C and an insulator cover for the accumulator may be added.
SERVICE PROCEDURES:
Water Valve Installation:
CAUTION: Coolant may be pressurized and hot. Use care to ensure that the coolant is at ambient temperature. Possible burns could result from contact with hot coolant.
1. Drain the coolant.
FIGURE 1:
FIGURE 2:
2. Cut the front heater inlet and outlet hoses approximately 3.5 inches from the cowl (see Figure 1).
^ It may be necessary to cut about one inch out of each hose to allow the water heater valve (4) to be inserted. The exact amount of hose will depend on hose routing for different engine configurations.
3. Insert the front heater water valve (4) in the hoses and install the hose clamps (2). Torque the clamps to 1.4 - 2.0 N-m (12 - 18 lbs. in.).
Important
If the wiring for the blower relay evidences any interference with the valve, add convoluted conduit to protect the wires and tie strap the wires as necessary to avoid rubbing.
4. Install plastic vacuum line on the water valve fitting and add a 3/32 rubber sleeve for cou pling (see Figure 1). Route vacuum line with the antenna cable to the grommet into the dash area (see Figure 2).
5. Punch a hole in the grommet with a pick, being careful not to puncture the antenna cable.
FIGURE 4. INSULATOR INSTALLATION:
FIGURE 3:
6. Route the vacuum line under the dash to the glove box area (see Figure 3).
7. Open the glove box and remove the rear panel to gain access to the rear of the dash. It will also be necessary to remove the insulator assembly under the dash for full access. Locate the Max A/C line going to the plenum valve and the air recirculation door valve. The line is black plastic with an orange stripe.
8. Cut the line and insert Tee coupling. See view 'A' in Figure 3. Use 3/32 rubber vacuum line for the couplings. Install the added vacuum line to the bottom leg of the Tee. Accumulator Insulation Installation:
1. Install the upper and lower insulators (3) and
(4) on the A/C accumulator assembly (see Figure 4).
Important
The insulator is designed for a G-van and must be modified for use on an S/T truck accumulator
2. Cut the lower insulator as necessary to fit the accumulator mounting bracket. Cut the upper insulator as necessary to accommodate the A/C pipes and fittings.
3. Install the clamp (2) on the insulators at the overlapped portion and tighten the clamp. Inspection:
1. Start the engine and check all hose connections for leaks.
2 Place the climate control lever in the *Max A/C" position and ensure that the water valve is operating properly.
PARTS INFORMATION:
WARRANTY INFORMATION For vehicles repaired under warranty use:
Labor Operation: T7001
Labor Time: .7 hr
NOTE: Labor Operation is coded to base vehicle coverage in the warranty system.