A/C - Poor Performance/Excessive Noise
88chevy27Number: 88-318-1B
Section: 1B
Date: JULY, 1988
Subject: LOSS OF A/C PERFORMANCE/EXCESSIVE A/C NOISE
Model and Year: 1987-88 SPRINT
TO: ALL CHEVROLET DEALERS
Some of the subject vehicles may exhibit excessive noise or loss of performance from the air conditioning system. These conditions may occur as a result of a loss of torque by the A/C compressor mounting bracket fasteners. In extreme circumstances, the loss of torque at one or more of the bracket fasteners may result in a cracked upper or lower bracket.
Vehicles exhibiting the above conditions should first be examined to establish if the fasteners are at the correct torque values and that the A/C compressor brackets are not cracked before performing A/C diagnostic procedures.
FIGURE 1:
Fastener location and torques are provided in Figure 1. All compressor mounting hardware is to be checked for proper torque.
Both upper and lower compressor mounting brackets are to be visually inspected for cracks and replaced as necessary following the procedures detailed for the installation or reinstallation of the A/C compressor and mounting brackets.
A/C COMPRESSOR MOUNTING BRACKET AND COMPRESSOR ASSEMBLY INSTALLATION PROCEDURES:
NOTICE: FAILURE TO SECURE ALL FASTENERS BY THE FOLLOWING INSTRUCTIONS MAY RESULT IN LOSS OF TENSION ON BOLTS DUE TO INSUFFICIENT TORQUE ON FASTENERS.
Reference Figure 1 for component identification numbers.
1. Install compressor (1) to lower bracket (2) using two (2) bolts 10 mm x 1.25 mm x 25 mm (3) place three (3) drops of Loctite 271 or equivalent on each bolt, and two (2) 10 mm wave washers (4). Snug the bolts until the compressor will stay in position but still rotate around bolts.
2. Install lower bracket and compressor on studs previously installed. Finger tighten two (2) nuts 10 mm x 1.25 mm (6) and wave washers (4) on studs. Install one (1) 8 mm x 1.25 mm x 20 mm bolt (7) and 8 mm wave washer (8) through ear of lower bracket into engine.
THE FOLLOWING SEQUENCE MUST BE USED: REFERENCE FIGURE 1 FOR TORQUE SPECIFICATIONS.
First tighten the 8 mm bolt (7). Second, tighten two (2) 10 mm nuts (6) Final assembly must be done from below vehicle using hand wrenches to assure sufficient torque.
3. Install upper bracket with idler pulley attached to engine using two (2) 8 mm x 1.25 mm x 20 mm bolts (7) and wave washers (8) and to compressor using one (1) 10 mm x 1.25 mm x 30 mm bolt (10) and wave washer (4). Tighten two (2) 8 mm bolts (7) and one 10 mm bolt (10).
4. THIS STEP IS VERY IMPORTANT: From below vehicle, tighten two (2) bolts (3) previously snugged through compressor ears (with Loctite), using hand wrenches to assure proper torque.
FIGURE 2:
5a. For Non Turbocharged Vehicles:
Install compressor drive belt around crank shaft pulley. Compressor clutch and idler pulley. Adjust belt to proper tension and torque idler pulley shoulder nut to 40 ft.lbs. See Figure 2.
5b. For Turbocharged Vehicles:
Install compressor drive belt around crankshaft and compressor pulleys. Adjust belt tension by positioning compressor, tighten retaining nut to 40 ft.lbs.
Labor Operation Number: T1353
Labor Time : 1.1 Hours