Evaporator; Refrigerant Line Restrictions; On-Vehicle Service; Refrigerant-11 Flushing Procedure - GMC G Service Manual

DIAGNOSIS FOR MALFUNCTIONING VALVE
Use the following procedure to identify a malfunctioning
valve.
1. Operate the system at normal idle. If the valve is
malfunctioning, the low pressure readings (evapora­
tor pressure) will be above specifications (figure 9).
2. The loss of system performance is not as evident
when the compressor head pressure is below 1379
kPa (200 psi). Increase the system head pressure by
partially blocking the condenser. Disconnect the
blower lead wire and operate the system to determine
if the evaporator pressure can be obtained.

EVAPORATOR

An inadequate supply of cool air can cause the evapora­
tor to malfunction. Check for a plugged core, a cracked
case or a leaking seal.
REFRIGERANT-11 FLUSHING
PROCEDURE
"Refrigerant-11 Flushing Procedure" does not apply to
R/V and G-Van models.
If there is a compressor failure, remove the old compres­
sor and install a new compressor with an in-line filter
(figure 27).
r
V V
101. Nut
102. Ferrule
Figure 27 — In-Line Filter Installation

FILTER INSTALLATION

• Discharge the system of Refrigerant-12. Refer to
"Discharging, Evacuating, Adding Oil and Charging
Procedures."
1. Locate an area of refrigerant liquid line between the
condenser and the orifice tube.
2. Cut out a section of liquid line one inch less than the
length of the filter with a tubing cutter.
3. Wedge a small cloth ball into both ends of the cut to
prevent debris from entering the system.
4.
File away the external burr.

ON-VEHICLE SERVICE

101
102
s
,
1 I
F-05214
AIR CONDITIONING IB -29
REFRIGERANT LINE
RESTRICTIONS
There are three types of refrigerant line restrictions:
1. Suction Line — A restriction will cause low suction
pressure at the compressor, low discharge pressure
and little or no cooling.
2. Discharge Line — A restriction will cause the pres­
sure relief valve to open.
3. Liquid Line — A restriction will be caused by low dis­
charge and suction pressure, and insufficient cooling.
5. Cut out the internal burr.
. Remove the cloth balls and any debris from the line
6
ends.
7. Place the nut over the condenser end of the liquid line
(figure 27).
. Install the ferrule with the small end toward the nut
8
(figure 27).
9. Remove the seal (O-ring) from the inlet side of the
filter (if equipped). Lubricate the seal with clean refrig­
erant oil and insert the tube into the compression fit­
ting until it bottoms out when tightened.
Tighten
• Nut. Refer to Figure 10.
10. Place the nut over the orifice end of the liquid line
(figure 27).
11. Install the ferrule with the small end toward the nut
(figure 27).
12. Remove the seal (O-ring) from the outlet side of the
filter (if equipped). Lubricate the seal with refrigerant
oil and insert the tube into the compression fitting of
the filter until it bottoms out when tightened.
Tighten
• Nut. Refer to Figure 10.
13. Reform the line. Do not crush or deform, as this may
cause a restriction.
14. If the filter is installed in a location where it may touch
another component, wrap the filter in closed cell foam
rubber to protect it from being damaged.
• Charge the system and leak test. Refer to
"Discarging, Evacuating, Adding Oil and Charg­
ing Procedures."