9B-38 1973 OPEL SERVICE MANUAL
expand and return to the original gaseous state. To
accomplish this transformation it begins to boil.
The boiling action of the refrigerant demands heat.
To satisfy the demand for heat, the air passing over
the core gives up heat to the evaporator and is subse-
quently cooled.\
DIAGNOSIS
GENERAL INFORMATIONThe following is a brief description of the type of
sympton each refrigerant component will evidence if
a malfunction occurs:
Compressor malfunction will appear in one of four
ways: noise, seizure, leakage, or low discharge pres-
sure.Resonant compressor noises are not cause for alarm;
however, irregular noise or rattles may indicate
broken parts or excessive clearances due to wear. To
check seizure, de-energize the magnetic clutch and
check to see if drive plate can be rotated. If rotation
is impossible, compressor is seized. Low discharge
pressure may be due to a faulty internal seal of the
compressor, or a restriction in the compressor.
Low discharge pressure may also be due to an insuffi-
cient refrigerant charge or a restriction elsewhere in
the system. These possibilities should be checked
prior to servicing the compressor. If the compressor
is inoperative; but, is not seized, check to see if cur-
rent is being supplied to the magnetic clutch coil
terminals.
CondenserA condenser may malfunction in two ways: it may
leak, or it may be restricted. A condenser restriction
will result in excessive compressor discharge pres-
sure. If a partial restriction is present, sometimes ice
or frost will form immediately after the restriction as
the refrigerant expands after pas?ing through the re-
striction. If air flow through the condenser or radia-
tor is blocked, high discharge pressures will result.
During normal condenser operation, the outlet pipe
will be slightly cooler than the inlet pipe.
Receiver-DehydratorA receiver-dehydrator may fail due to a restriction
inside body of unit. A restriction at the inlet to the
receiver-dehydrator will cause high head pressures.
Outlet tube restrictions will be indicated by low headpressures. Outlet tube restrictions will be indicated
by
low head pressures and little or no cooling. An
excessively cold receiver-dehydrator outlet may be
indicative of a restriction.
Expansion ValveExpansion valve failures usually will be indicated by
low suction and discharge pressures, and insuff%ient
evaporator cooling. The failure is generally due to
malfunction of the power element and subsequent
closing of the valve. A less common cause of the
above symptom is a clogged inlet screen.
EvaporatorWhen the evaporator malfunctions, the trouble will
show up as inadequate supply of cool air. A partially
plugged core due to dirt or a faulty blower will gener-
ally be the cause.
Refrigerant Line Restrictions
Rest~rictions in the refrigerant lines will be indicated
as follows:
I. Suction Line - A restricted suction line will cause
low suction pressure at the compressor, low dis-
charge pressure and little or no cooling.
2. Discharge Line -A restriction in the discharge line
generally will cause the pressure relief valve to open.
3. Liquid Line
- A liquid line restriction will be evi-
denced by low discharge and suction pressure, and
insufficient cooling.
Use of Receiver-Dehydrator Sight Glass for
DiagnosisAt temperatures higher than 70 degrees F, the sight
glass may indicate whether the refrigerant charge is
sufficient. A shortage of liquid refrigerant is in-
dicated after about
five minutes of compressor oper-
ation by the appearance of slow-moving bubbles
(vapor) or a broken column of refrigerant under the
glass. Continuous bubbles may appear in a properly
charged system on a cool day. This is a normal situa-
tion. If the sight, glass is generally clear and perform-
ance is satisfactory, occasional bubbles do not
indicate refrigerant shortage.
If the sight glass consistently shows foaming or a
broken liquid column, it should be observed after
partially blocking the air to the condenser. If under
this condition the sight glass clears and the perform-
ance is otherwise satisfactory, the charge shall be
considered adequate.
REFRIGERANT COMPONENTS ALL MODELS96-39
In all instances where the indications of refrigerant
shortage continues, additional refrigerant should be
added in
l/4 lb. increments until the sight glass is
clear.
An additional charge of l/4 lb. should be ad-
ded as a reserve. In no case should the system be
overcharged.
LEAK TESTING SYSTEM
The following two methods are recommended when attempting to locate refrigerant leaks in the system.
Loss of
regrigerant is always indicative of a leak since
refrigerant is not consumed and does not wear out.
1. Open Flame Method
- This method utilizes a gas
operated torch type leak detector (J-6084). Use of
this method is recommended when checking for
leaks in confined areas. To perform test, light torch
and adjust to obtain a pale blue flame, approximately
3/8 inch in height, in burner.
Explore for leaks by moving end of search tube
around suspected area. Check bottom of connections
since Refrigerant-12 is heavier than air and will be more apparent at underside of fittings. The flame
color will turn yellow-green when a small leak is
detected. Large leaks will turn the flame blue or
purple.
WARNING:
Do not breathe fumes resdting from
burning of
refrigerant gas. These fumes az ex-
tremeiy poisonous.
2. Liquid Leak Detectors - This method utilizes a
solution which will bubble (soap solution) to signify
a gas leak. Use of this method of checking is recom-
mended for locating small leaks.
FUNCTIONAL TESTING SYSTEM
Functional testing is a measurement of the air condi-
tioner system performance to determine if discharge
air temperature, pressure in suction line, and pres-
sure in discharge line are within specific limitations.
To perform Functional test proceed as follows:
1. Remove protective caps from the compressor
adapter fittings located on compressor.
SCHRADER
ADAPTER J-5420
1II rDISCHARGE LINE
COMPRESSOR
VALVE
LOW PRESSURE
\ GAUGE\
HIGHGLR;B;URE
MANIFOLD AND
-GAUGE SET
J-5725-01
r
GAUGE LINES
(5) J-5418
9B-31
Figure 9B-40 Functional Test Set-Up
