Chevrolet Light Duty Truck 1973, Руководство по обслуживанию

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INSUFFICIENT COOLING D IA G NO SIS CHART (EXCEPT C -K FOUR-SEASON SYSTEM)
The fo llo w in g procedures should be applied before perform ance testing an A/C System.
1. Check fo r proper belt installation and tension w ith J-23600.
2. Check fo r proper clutch coil term inal connector insta llation.
3. Check fo r clutch air Gap (.022 - .057).
4. Check fo r broken, burst, or cut hoses. Also check fo r loose fittin g s on all components.
5. Check fo r condenser air blockage due to foreign m aterial.
6. Check fo r proper air ducting hose connections.
7. Check heater tem perature door adjustm ent, adjust if incorrect.
8. Check evaporator sealing fo r air leak, repair if leaking.
9. Install pressure gages and therm om eter and make perform ance test.
NO R M AL A IR FLOW
CHECK A IR FLO W
IN O OR LOW A IR FLOW
| CHECK DISC H AR G E A IR T EM P ER ATU R E (SEE PERFORMANCE D A T A ) |
D ISC H AR G E T E M P E R A TU R E HIGH O U TLE T AIR
A T O U T L E T COLD
TEM PERATURE
BLOWER NO T O PE RATING
CHECK BLOW ER O PE R ATIO N
)_ t
CHECK FOR BLOWN FUSE, D E FE C TIV E BLO W ER SWITCH,
BRO KEN W IRE, LOOSE CONNECTIO NS. LOOSE BLOW ER MOTOR
G ROUND W IRE OR IN O P E R A T IV E BLOW ER MOTO R.
CHECK FOR A IR LE A K S T H R O U G H DASH PANE L.
DOORS, W INDOW S, OR FROM H E A T E R .
CHECK SIGH T GLASS
N O R M A L BLOWER O PE R A TIO N | I
Check fo r loose or disconnected air d is trib u tio n ducts,
restricted o r leaking air ducts, p artia lly closed air o u t­
let valve or clogged evaporator core, if above check is
OK, check fo r ice blocking evaporator.
a m i n g
| -
NO FO AM IN G
ICE BLO C K IN G
EVAP O R A TO R
SYSTEM IS P R O B A B LY LOW ON R E F R IG E R A N T .
CHECK FOR LEAK S, R E P A IR , A N D A D D
R E F R IG E R A N T . IF FO A M IN G S T IL L OCCURS,
CHECK FOR R E S T R IC TIO N IN R E F R IG E R A N T
SYSTEM BETW EEN CONDENSER A N D SIGH T
GLASS.
1. SYSTEM MAY BE E ITH E R F U L L Y C H ARG ED OR EM PTY.
FEEL HIGH AND LOW PRESSURE PIPES A T COMPRESSOR.
HIGH PRESSURE PIPE SH O U LD BE W ARM . LOW PRESSURE
PIPES SHOULD BE COLD .
2. IF PIPES ARE NOT IN D IC A T IN G PROPER TE M P ER ATU R ES ,
RECHARGE SYSTEM AS REC O M M EN D ED . IF N O ZZ LE A IR
TEM PERATURE IS S T IL L H IG H . CHECK E V AP O R ATO R
PRESSURE.
LOW E V AP O R ATO R
‘ PRESSURE
X
CHECK FOR LOW EVAP O R A TO R PRESSURE
1. A LLO W SYSTEM TO W ARM UP.
2. STOP A N D R EST AR T ENG INE.
3. CHECK EVAP O R A TO R PRESSURE
IM M E D IA T E L Y A F T E R RESTART A N D
PULL DOWN OF EVAP O R A TO R PRESSURE.
N O R M A L EVAP O R ATO R
PRESSURE
LOW EVAP O R A TO R
* PRESSURE
'C H E C K EVAPO RATO R PRESSURE
CHECK EVAP O R A TO R O U T L E T LIN E
E V AP O R ATO R O U TLE T
L IN E W ARM
I
HIGH E V AP O R ATO R
*
PRESSURE
I
SYSTEM HAS EXCESS M O IS TU R E. R EPLACE R ECE IVER
D E H Y D R A T O R A N D E V A C U A T E T H O R O U G H L Y . RECHARGE
SYSTEM.
CHECK COMPRESSOR D ISC H AR G E PRESSURE
N O R M A L
E V AP O R ATO R PRESSURE
Check fo r m alfu nctionin g
expansion valve-See
Com ponent Diagnosis.
1. CHECK FOR L IQ U ID L IN E R ESTRICTIO N
(FRO S T SPOT ON LIN E ). IF NOT,
2. CHECK FOR PLUG GED IN L E T SCREEN IN
EXPA N SIO N V A L V E . IF NOT,
3. CHECK FOR D E FE C TIV E EXPA NSIO N V A L V E
BY R E M O V IN G V A L V E A N D BLO W ING THRO UG H
V A L V E . IF U N A B LE TO BLO W THR O U G H V A L V E ,
B U LB IS D IS C H AR G ED . REPLACE EXPANSION
V A L V E .
| Check Compressor Discharge Pressure.
HIG H DISC H AR G E PRESSURE
LOW DISCH ARGE PRESSURE N O R M A L DISC H AR G E PRESSURE
LOW DISCHARGE
* PRESSURE
I
Check fo r m alfunctioning
expansion valve-See
Component Diagnosis.
X
1. Check engine cooling system, fan clutch and check
fo r restricted air flo w thru condenser.
2. Check expansion valve bulb contact. Correct if
necessary.
3. Check fo r refrigerant restriction in condenser.
Return bends at equal elevation should be
approxim ately same tem perature. If temperature
of bends is appreciably d iffe re n t, the cooler
bend indicates a restricted circu it, replace con­
denser if restriction is foun d, If condenser is OK,
check fo r air in system. To check observe o u tle t
air tem perature and compressor discharge
pressure w hile slow ly discharging system at
receiver inlet connection.
Check fo r restriction in liquid line,
p a rtia lly plugged inlet screen at
expansion valve, or defective
expansion valve, replace valve if
defective.
X
R efrigeration System is ok
1. Check fo r proper fu n c tio n of heater T E M P E R A TU R E door.
2. Check fo r proper sealing of evaporator case.
3. Check fo r proper operation and seal around tem perature door.
4. Non-Foam ing sight glass does n ot always indicate a fu lly
charged system. Add 1/2 lb. refrigerant and observe
perform ance.
5. Check fo r excess oil in system. A sym ptom of excess o il is a
slipping clutch or belt or broken belt. T o remove excess oil
in system consult service manual.
’ REFER TO PERFO RM ANCE
C H A R T FOR CO RRECT PRESSURES
Fig. 101-Insufficient Cooling Diagnosis-Except C-K Four-Season System
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