GMC chervolet camaro 1999 Service Manual page 217

1-126 HVAC System - Manual
Expansion (Orifice) Tube Description
82109
The plastic expansion (orifice) tube (2) is made of a
mesh-screen (1) and orifice (3). The expansion (orifice)
tube is located in the evaporator inlet pipe at the
orifice connection. The tube restricts the high pressure
liquid refrigerant in the liquid line. This restriction
meters the refrigerant flow to the evaporator as a low
pressure liquid. The expansion tube and orifice
have filter screens which protect from contamination
on both the inlet and outlet sides of the tube. When the
engine is OFF the refrigerant. in the system flows
from the high pressure side
of
the system to the low
pressure side until the pressure is equalized. This may
be detected as a hissing sound for 30-60 seconds
and is a normal condition.
Evaporator Description
The evaporator cools and dehumidifies air before the
air enters the passenger compartment. The following
events occur in the evaporator:
1. Low-pressure, low temperature liquid/vapor
refrigerant enters the evaporator.
2. The refrigerant flows through the evaporator's
tubing.
3. The refrigerant evaporates.
4. The refrigerant exits the evaporator as
low-pressure, low temperature, mostly vapor
refrigerant.
5. As the refrigerant evaporates, the refrigerant
absorbs heat from the air flowing over the
evaporator.
As the process of heat loss from the air ,to the
evaporator core is taking place, any moisture
(humidity) in the air condenses on the outside surface
of the evaporator core and the moisture drains off
as water.
HVAC
Condenser Description
The condenser receives high pressure, high (
temperature refrigerant vapor from the A/C compressor.
The condenser is made up of aluminum tubing and
cooling fins. which allow rapid heat transfer away from
the high-pressure, high temperature refrigerant vapor.
The cooling fins cause the high pressure, high
temperature refrigerant "apor to condense into a
high-pressure; medium temperature liquid.
Accumulator Description
1
Legend
(1) Refrigerant Vapor Inlet
(2) Inlet
(3) Baffle
(4) Internal Tube
(5) Desiccant Bag
(6) Filter
2
(7) Oil Bleed Hole Location-In the Tube
(8) Outlet
82105
The sealed accumulator is connected to the evaporator
outlet pipe. The accumulator stores the refrigerant
(vapor and liquid) and the oil from the evaporator.
A desiccant at the accumulator bottom dries any
moisture in the system. An oil bleed hole at the
accumulator outlet pipe end provides the oil return
path to the compressor. The accumulator is not
serviceable and should only be replaced when leaking
due to the following conditions:
• Perforation
• A damaged sealing area
• Damaged fastener threads
• Outside air has entered the system for extended
periods of time
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