DeVille V8-273 4.5L (1989)
High Pressure Safety Valve HVAC: All Technical Service Bulletins
A/C - Insufficient Cooling
Bulletin No.
T-90-23
File in Group
1
Number
68
Corp. Ref. No.
911205
Date
Nov. 1989
Figure 1 - Pressure Relief Valve
SUBJECT:
A/C SYSTEM HIGH PRESSURE RELIEF VALVE "BLOW-OFF"
MODELS AFFECTED: 1989 DE VILLES AND FLEETWOODS
Some 1989 DeVille and Fleetwood A/C systems may experience an insufficient cooling or system condition due to refrigerant "blow-off" at the pressure
relief valve found on the rear head of the compressor. Refer to Figure 1. This may be caused by a knock-out slug (from the muffler) becoming caught in
the muffler.
In the case of an inoperative system, always check for a refrigerant discharge through the pressure relief valve. As seen in the illustrations below, if the
relief valve has not been released, the piece of tape will be intact across the valve. Refer to Figure 1. Upon discharge from this valve the tape will be torn
free and evidence of refrigerant oil will appear about the valve and surrounding area.
If the pressure relief valve has been opened and has released refrigerant, use the following procedure:
CAUTION:
Before any service is attempted which requires opening of the refrigerant system, the technician should be thoroughly familiar with
the important information contained under the heading "on-car service" in Section 1C of the Service Information Manual.
1.
Check the following:
a.
Outer surfaces of radiator and condenser cores for blockage. Check between the condenser and radiator. Clean as needed.
b.
Restrictions or kinks in evaporator and condenser cores, hoses, tubes, etc. Replace as needed.
C.
Blower fan operation. Repair as needed.
d.
Air ducts for leaks and restrictions. Low air flow may mean a restricted or frozen evaporator core. Repair as needed.
e.
Compressor clutch for slippage. Check compressor clutch coil current (3-6 amps) and compressor clutch. Refer to Section 8A for electrical
schematics. Repair/replace as needed.
f.
Drive belt for improper tension or excessive wear. Replace as needed.
g.
Orifice tube for plugged condition. Clean or replace as needed.
2.
If no blockage is found, replace A/C hose assembly, P/N 25535804. Parts are currently available from GMSPO.
WARRANTY INFORMATION
VEHICLE SERIES
Operation
Operation Description
Number
C
D
E
J
K
V