Pontiac TRANS AM 1977 Service Manual page 71

1 8-20
1977 PONTIAC SERVICE MANUAL
C.C.O.T. A/C SYSTEM DIAGNOSTIC PROCEDURE
"INSUFFICIENT COOLING"
COMPRESSOR CLUTCH IS
ENGAGED OR CYCLING
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FEEL LIQUID LINE NEAR COMP. LOW-PRESS. CUT-OFF SWITCH
RESTRICTION~N HIGH SIDE
OF SYSTEM. VISUALLY LOOK
FOR FROST SPOT TO LOCATE
RESTRICTION. REPAIR.
FEEL
EVAPORATOR
INLET PIPE NEAR
THERMOSTATIC SWITCH CAPILLARY TUBE CONNECTION
AND
ACCUMULATOR CAN SURFACE
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EVACUATE & RECHARGE.
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SYSTEM
(0.K.)
INLET PlPE COLDER
T H A N ACCUMULATOR SURFACE
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LEAK CHECK SYSTEM & REPAIR LEAK. I F NO LEAK
IS FOUND, CHECK EXPANSION TUBE (ORIFICE)
FOR PLUGGED FILTER. EVACUATE & RECHARGE. RE-CHECK
INLET PlPE AND ACCUMULATOR SURFACE TEMPERATURES.
WARM AS ABOVE
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REPLACE EXPANSION'TUBE (ORIFICE)
AND
EVACUATE AND RE-CHARGE
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SAME TEMP. (COLD)
ACCUMULATOR COLDER THAN INLET
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INLET PlPE & ACCUMULATOR SURFACE
SAME TEMPERATURE OR
ACCUMULATOR SURFACE COLDER THAN INLET
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INSTALL
THERMOMETER
I N A l C OUTLET AND
CHECK SYSTEM TO THESE
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1. TURN ENGINE "OFF". ( A L L SERlESl
2. CLOSE A L L DOORS & WINDOWS. (ALL)
3. HOOD UP & ENGINE EXHAUST SUITABLY VENTILATED. (ALL)
4. SLIP FAN CLUTCH SPRING OUT FROM ITS LOCATING NOTCH BY HAND TO REMOVE
SPRING TENSION TO CLUTCH. (A & G SERlESl
4A. MANUALLY DISENGAGE FAN CLUTCH BY SLIPPING ITS SPRING OUT FROM LOCATING
NOTCH BY HAND & TIGHTEN TO FIRST NOTCH PAST NORMAL SET POSITION. IB.F.X,H).
5. TURN AIC OFF. (ALL1
6.
INSTALL GAGE SET. I A L L l
7. PROPERLY OPERATING TUNED ENGINE (CHOKE OPEN & OFF FAST IDLE SPEED CAM). ( A L L I
8. RUN ENGINE AT 1500 R.P.M. I N NEUTRAL (A&G). 2000 RPM FOR B,F.X,H SERIES
9. FOR MINIMUM OF 7-10 MINUTES WlTH AIC TURNED ON TO "MAX" POSITION. (ALL)
10. WlTH AIR OUTLETS OPEN. (ALL)
11. THE INTERIOR OF CAR BELOW 90' OR 3 2 O ~ . ( A L L )
12. AND TEMP. SETTING A T FULL "COLD". (ALL)
13. AUXILIARY FAN (2' DIA., 2.2A. 115VI OPERATING AT FRONT BUMPER 1B.F.X.H)
14. THERMOMETER PLACED I N FRONT OF VEHICLE GRILLE &ANOTHER I N LEFT CENTER
I.P. OUTLET (ALL)
15. CHECK SYSTEM TO BELOW PRESS-TEMP. CHART (ALL)
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PERFORMANCE PRESSURE
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TEMPERATURE CHART
SEE FIG. lB2OC FOR CHART
Fig. 18-208 1977 C.C.O.T. System Diagnostic Procedure