OPERATOR'S MANUAL

Heater and Air Conditioner Preventive Maintenance
– 216 – Y53-6027
Medium Duty (R05/09)
HEATER AND AIR CONDITIONER
Introduction
The combination heater-air conditioner provides comfort for
those in the cab through accurate control of the cab environ-
ment in all weather conditions. Regular attention to the items
below will help you keep the heater-air conditioner unit run-
ning well.
WARNING! Excessive heat may cause the pres-
surized components of the air conditioning sys-
tem to explode possibly causing death or
personal injury. Never weld, solder, steam clean,
or use a blow torch near any part of the air con-
ditioning system.
• If a refrigerant leak develops in the presence
of excessive heat or an open flame, hazard-
ous gases may be generated. These gases
may cause unconsciousness or death. If you
become aware of a refrigerant leak on your
vehicle have your system service immedi-
ately and observe the following precautions:
• Stay away from the hot engine until the
exhaust manifold has cooled.
• Do not permit any open flame in the area.
Even a match or a cigarette lighter may gen-
erate a hazardous quantity of poisonous
gas.
• Do not smoke in the area. Inhaling gaseous
refrigerant through a cigarette may cause
violent illness.
Heater
• Check all heater controls for full-range operation.
• Check hoses, connections, and heater core for condition
and leaks.
• Check the drain pan of the fresh air vent for trapped
water before assuming that there is a leak in the heating
system. If the heater core is leaking, a reliable radiator
shop should be able to repair it.
• Check the heater core for debris blocking the air flow. If
the blower and air controls are functioning properly, yet
the heater is not operating properly, the heater core or
the hot water valves may be clogged or closed. Clean
the heater core if necessary. If the condition persists,
take the vehicle to a Peterbilt Dealer for proper heater
service or repair.