Freightliner Trucks Business Class Truck MB80

1. Clean the valve exterior and inspect it for corrosion and damage.

2. Inspect the air lines connected to the valve for signs of wear or damage. Replace the lines as needed.

3. Check the valve for leakage.

3.1 Apply the service brakes and hold them on full line pressure of at least 80 psi (550 kPa).

3.2 Check the air line fittings for leaks; tighten or replace the fittings as needed.

3.3 Coat the exhaust port and body of the valve with soapy water, and check for leakage. Leakage is excessive if it produces a 1-inch (25-mm) bubble within 5 seconds.

If the brake valve does not function as described above, or if leakage is excessive, replace it with a new or remanufactured unit. Repeat the leakage checks before placing the brake valve in service.;

Air Cleaner Element Inspecting and Replacing

Replace the air cleaner element at the recommended interval or when the air restriction indicator reaches 22 inH2O on a vehicle with an MBE engine, or 25 inH2O on a vehicle with a Detroit Diesel, Caterpillar, or Cummins engine, if equipped with an air restriction indicator. For replacement instructions, see Group 09 of the Business Class Trucks Service Manual.

Reset the air restriction indicator.

If the maximum restriction is not reached, record the air restriction value. If the value is higher than the previous recording, reset the air restriction indicator.

If the value is lower than the previous recording, inspect the air cleaner and air cleaner element of cracks, leaks, or any other damage.

If the air cleaner or air cleaner element is damaged, replace it and reset the air restriction indicator.

Replace the air cleaner element at the recommended interval or when the air restriction indicator reaches 22 inH2O on a vehicle with an MBE engine, or 25 inH2O on a vehicle with a Detroit Diesel, Caterpillar, or Cummins engine, if equipped with an air restriction indicator. For replacement instructions, see Group 09 of the Business Class Trucks Service Manual.

1. Apply the parking brakes and chock the tires.

2. Make sure the refrigerant compressor drive belt is not damaged, and is correctly tensioned. Also check the tightness of the compressor mounting fasteners. For instructions and torque values, see Group 01 of the Business Class® Trucks

3. Using a feeler gauge, check for correct clutch clearance. For instructions, see Group 83 in the Business Class® Trucks Service Manual.

4. Inspect the compressor clutch coil wire. Check the connector for damage or looseness. Replace the wire if it is damaged.

5. Check for broken, burst, or cut hoses. Also check for loose fittings on all parts.

WARNING: Wear eye protection when using compressed air or high-pressure water to clean parts, as permanent harm to eyes could result from flying debris.

6. Check for a build-up of road debris on the condenser fins. Using a whiskbroom and air pressure, or a spray of soapy water, carefully clean off the condenser; be careful not to bend the fins.

End Cover Heater and Thermostat Assembly Check

Voltage to the heater and thermostat assembly

Corrosion in the vehicle wiring harness?

Thermostat and heater operation

Check the reservoirs for moisture

Amount of moisture found in reservoirs

Check the mounting and connecting lines

Tighten the fasteners attaching the air dryer to the vehicle to 28 lbf·ft (38 N·m) for SAE grade 5, 3/8–16 fasteners

Tighten the fasteners attaching the air dryer to the vehicle to 135 lbf·ft (183 N·m) for SAE grade 5, 5/8–11 fasteners

Check all air lines, fittings, and electrical connections for damage, leakage, or looseness

List of damaged or leaking parts

Replace damaged or leaking parts, and tighten loose fittings or electrical connections

Sign off on the air dryer inspection