freightliner M2 Plus Maintenance Manual page 169

Heater and Air Conditioner
83–00 Safety Precautions
Safety Precautions in this section apply to all
procedures within this group.
DANGER
When working on the vehicle, shut down the
engine or motor, set the parking brake, and chock
the tires. Before working under the vehicle, always
place jack stands under the frame rails to ensure
the vehicle cannot drop. Failure to follow these
steps could result in serious personal injury or
death.
83–01 Air Conditioner
Inspecting
Refrigerant Compressor
Inspection
1. With the vehicle parked on a level surface, apply
the parking brakes and chock the tires.
2. Operate the heater and, if equipped with an air
conditioner, the air conditioner to check for
proper operation in all modes.
3. Open the hood.
4. Check the condition of the refrigerant
compressor clutch assembly. If the friction
surface of the pulley shows signs of excessive
grooving due to belt slippage, replace both the
pulley and the drive plate.
5. Inspect the refrigerant compressor drive belt for
damage. If needed, replace the drive belt.
6. Check the tightness of the compressor mounting
fasteners. The torque value for the mounting
fasteners is 15 to 19 lbf·ft (20 to 26 N·m).
7. Inspect the drive plate. If the friction surface of
the drive plate shows visible signs of damage
due to excessive heat, make sure the refrigerant
compressor turns freely. If the compressor does
turn freely, replace the drive plate and clutch
assembly. For instructions, see Group 83 of the
Business Class® M2 Plus Workshop Manual. If
the compressor does not turn freely, replace the
compressor. For instructions, see Group 83 of
the Business Class M2 Plus Workshop Manual.
Business Class M2 Plus Maintenance Manual, 02/10/2023
8. Use a feeler gauge to check that the drive plate
clutch clearance is 0.012 to 0.024 in (0.3 to 0.6
mm). If the gap is not even around the clutch,
gently tap down at the high areas. If the overall
gap is out of spec, remove the drive plate
assembly and change the shims as necessary.
For instructions, see Group 83 of the Business
Class M2 Plus Workshop Manual.
9. Check that the wiring harness connector is not
damaged or loose. Replace the wiring harness if
it is damaged.
10. Check the overall condition of the air conditioning
hoses. Look for cracks, cuts, and abrasions on
the hoses. Replace damaged hoses.
11. Check for a buildup of road debris on the
condenser fins. Using air pressure and a whisk
broom or a soapy spray of water, carefully clean
off the condenser. Be careful not to bend the
fins.
12. Check the moisture indicator on the receiver-
drier. See Fig. 1. If the indicator is a deep cobalt
blue, the refrigerant charge is dry. If the indicator
is not blue, the system is contaminated with
water. If the system is contaminated, recover the
refrigerant, replace the receiver drier, evacuate
the system, and add a full refrigerant charge. For
instructions, see Group 83 of the Business Class
M2 Plus Workshop Manual.
13. Close the hood and remove the chocks from the
tires.
83–02 HVAC Air Filter
Replacing
The HVAC air filter must be replaced every six
months or 60,000 miles (97 000 km) to permit proper
operation of the HVAC system.
1. With the vehicle parked, apply the parking
brakes, and chock the tires.
2. Remove the lower HVAC cover in the cab. For
instructions, see Group 60 of the Business Class
M2 Plus Workshop Manual.
3. Disconnect the wiring harness from the
evaporator probe.
4. Remove the capscrews that attach the
evaporator service cover to the HVAC assembly.
Remove the evaporator service cover.
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