Advertisement
AIR CONDITIONING
24-1 9
ed in this manual. Experience has proven this to be
the surest and quickest way to locate and correct the
cause of unsatisfactory performance.
If the Compressor Capacity Test (Fig. 20) is per-
formed immediately after completing the Evaporator
Pressure Regulator Valve Test, the compressor will be
up to operating temperature and most of the refriger-
ant oil will have been returned to the compressor
crankcase.
If the system has been standing any length of time,
it
will be necessary to perform the following opera-
tions before starting the Compressor Capacity Test:
1.
Attach the gauge
set
manifold.
2.
Start the engine and adjust speed to 1250 rpm.
Turn the blower switch to position NO. 2, move tem-
perature control to
"Off'
and push in the "Cool" but-
ton.
3. Allow the air-conditioning system to operate at
full capacity for at least 15 minutes. This will cause
most of the compressor oil in the system to be re-
turned to the compressor crankcase.
It will also in-
sure that the compressor is up to operating tempera-
ture which is very important when making this test.
Discharging the System
When making the Compressor Capacity Test, the
compressor must be disconnected from the
rest
of
the system. That means the system must be dis-
charged.
(1)
Insert the manifold discharge hose into an ex-
haust ventilation system or to the outside of the
building so that the service area will not be filled with
refrigerant vapor.
(2) Fully open the manifold needle valve.
(3) Open the discharge (right-hand) gauge valve a
small amount. This will allow the refrigerant vapor
to discharge
slowly.
CAUTION: Do not open the valve fully and allow
the system to discharge rapidly, since this would
sweep some of the refrigerant oil out with the re-
f rigerant.
(4)
Allow the system to discharge until the dis-
( 5 )
Open the suction (left-hand) gauge valve to
re-
charge pressure gauge registers zero.
lease any vapor trapped at the suction side.
Test Preparation and Connections
After the system is completely discharged, isolate
the compressor and connect the gauge set manifold
as follows:
(1)
Disconnect the discharge (muffler) line from
the compressor discharge adapter. Cap the discharge
adapter outlet with a
Y 2
inch cap. Seal the discharge
(muffler) line.
(2) Disconnect the evaporator suction line (hose)
from the suction muffler. Cap the suction muffler
in-
let with a
? h 8
inch cap. Seal the suction line.
The compressor is now isolated from the system
and sealed at both the suction and the discharge
sides. Refer to Figure 20, and make the following
gauge set manifold connections:
(3) Disconnect the
test
hose and adapter from the
compressor inlet port.
(4)
Remove the valve body from the compressor in-
let port. The tire valve stem, Tool C-3788, can be used
for this purpose.
( 5 )
Disconnect the
test
hose an.d adapter from the
suction service port
of
the fitting.
(6)
Install test cap (SP-2922) at the center mani-
fold outlet.
NOTE: Be sure that the test cap is perfectly clean.
Particles adhering to the cap or the metering orifice
can restrict flow and cause false readings. Never
use a wire or probe of any kind to clean the cap.
Wash it with clean solvent and blow dry with com-
pressed air.
(7)
Make sure both the left and right gauge valves
are open.
The compressor can now be operated as an air
pump. Air will be drawn through the compressor in-
let port, compressed and delivered (through the test
hose attached to the discharge port) to the gauge
set
manifold. Compressor capacity is determined by not-
ing the pressure registered at the discharge gauge
when the compressor is driven at an engine speed of
exactly
500 rpm.
IMPORTANT: The tachometer used must be accu-
rate. The compressor capacity test results are de-
pendent upon controlling engine speed at exactly
500
rpm.
Test Pressures and Results
500
rpm.
(1)
Start the engine and adjust speed to exactly
ENGINE EXACTLY 500 R P M
190 P S I MINIMUM
Fig. 21-Compressor
Test Pressure
Hide quick links:
Advertisement
