Improving the Air Conditioning System in 793D Off-Highway Trucks{1802} Caterpillar

Off-Highway Truck:

793D (S/N: FDB1-UP)

Introduction

Do not perform any procedure in this Special Instruction until you have read the information and you understand the information.

This Special Instruction describes improving the air conditioning (AC) system by performing the following service in order to reduce the damaging effects of vibration:

• Installing new support brackets for the AC compressor

• Routing and securing the wiring and the hoses

• Installing a new bracket for the guard

Required Parts

Note: Updating of the belt tensioner is recommended. Use the following parts if tensioner will be replaced.

Rework Procedure

Removal

Remove the AC Compressor

Illustration 1	g02468496
(1) 217-4448 Refrigerant Compressor Gp (2) 303-8753 Bracket As

1. Remove compressor (1). Refer to Disassembly and Assembly, RENR8334-03, "Refrigerant Compressor - Remove and Install".

2. Remove bracket (2).

3. Clean the mounting surface on the engine.

Note: Use a standard 186-4195 Serpentine Belt for reassembly.

Installation

Install the AC Compressor

Illustration 2	g02801517
(1) 218-0324 Refrigerant Compressor Gp (2) 5B-9603 Bolt (3) 5M-2894 Hard Washer (4) 4P-7581 Clip (5) 9S-8752 Full Nut (6) 187-4599 Support (7) 9X-8878 Bolt (8) 5P-8245 Hard Washer (9) 0S-1588 Bolt (10) 4P-8134 Clip (11) 367-9766 Bracket As

1. Install compressor (1) on support (6) before installation. Use two bolts (2), four washers (3), and two nuts (5) .

2. When installing the upper compressor mounting bolt, pre-position clip (4) between washer and compressor.

3. Install clip (10) with the tab facing the front of the engine using bolt (9), nut (5), and two washers (3).

4. Hand tighten the bolts. Do not tighten the bolts at this time. The bolts will be torqued in a later step.

5. Mount compressor (1) and support (6) onto the engine. Use three bolts (7) and three washers (8). Torque the bolts to 135 N·m (100 lb ft).

6. Remove and discard cover plate from back of compressor.

Manifold and AC Lines Install

Illustration 3	g02470096
Typical Installation (1) 304-8968 Hose As (2) 304-8967 Hose As (3) 085-8091 Bolt (4) 8T-4121 Hard Washer

1. Install the original 304-2740 Manifold onto the compressor with new 229-4896 O-Ring Seals .

2. Torque retainer bolt (3) to 35 ± 3 N·m (26 ± 2 lb ft).

3. Install the 186-4195 Serpentine Belt .

4. Install low-pressure hose (1) and high-pressure hose (2) .

Wiring

Illustration 4	g02474977
(1) 6K-8179 Clip (2) 0S-1588 Bolt (3) 5M-2894 Hard Washer (4) 9S-8752 Full Nut

Note: Avoid tight bends when routing wires. Tight bends will lead to wire failure and electrical issues.

Note: If installing optional 344-2689 Relay Kit , refer to Special Instruction, REHS4499-03, "Testing the Refrigerant Compressor Protection Module" for installation procedure.

1. Place the AC compressor clutch wire into clip (1) .

2. Install clip (1) with bolt (2), nut (4), and two washers (3) .

3. Torque to the bolt to 41 N·m (30 lb ft).

Illustration 5	g02747903
(5) Compressor clutch harness (6) 9X-6772 Cable Strap

1. Attach the wire harness to clips with cable straps (6). Ensure that the compressor clutch harness (5) is attached to the rear of the top clip.

2. Torque the compressor mounting bolts to 43 ± 3 N·m (32 ± 2 lb ft)

Guards

Illustration 6	g02759636
(1) 147-6610 Bracket (2) 2A-4639 Bolt (3) 198-4766 Hard Washer (4) 8M-9124 Washer (5) 9S-8752 Full Nut (6) 0S-1588 Bolt (7) 5M-2894 Hard Washer (8) Edge of guard

1. Place bracket (1) onto the guard covers. Ensure that the edge of the bracket aligns with edge of guard (8) as shown.

2. Scribe the bolt hole locations through the bracket holes. Drill holes with a 25/64 drill bit.

3. Install bolt (2), washer (3), washer (4) and nut (5). Install the other bolt (6), the other washer (3), washer (7), and the other nut (5) .

Hose Clamping

Illustration 7	g02475586
(1) 253-0436 Bracket (2) 0S-1588 Bolt (3) 6V-8801 Nut (4) 8T-4896 Hard Washer (5) 5P-1075 Hard Washer (6) Clips (Upper and Lower) (7) Grommet (8) High Pressure Hose (9) Low Pressure Hose

Illustration 8	g02475554
(10) 1W-3011 Spacer (11) 1A-5964 Bolt (12) Boost pressure sensor wire

1. Use the bolt and the washer currently installed on the front left side of the engine on the water manifold. Install bracket (1) at location (13).

2. Install three pairs of clips (6) and grommets (7) at the locations (13) and (14). Use 5P-7464 Clip , 5P-7465 Clip , and 6V-7359 Grommet for the low-pressure hose. Use 5P-7462 Clip , 5P-7463 Clip , and 6V-0683 Grommet for the high-pressure hose. The low-pressure hose is toward rear of engine. The high-pressure hose is toward the front of the engine.

3. Use two spacers (10), clips (6), washers (5), and bolts (11) as shown in Illustration 8. Install clips onto spacers (10) at location (14) .

4. Use bolt (2), washers (4) and (5), and nut (5). Install last pair of clips (6) onto bracket (1) at location (13) .

5. Route the boost pressure sensor wiring over the hoses as shown (13) .