Chevrolet Light Duty Truck 1973, Service Manual

Page: 107 / 979

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Hitting
INSUFFICENT C O O L IN G -F O U R SEASON S Y STE M (C -K M O D ELS)
i
M ove temperature lever rapid ly back and forth from max
heat to max. cold Listen for temperature door hitting at each end
1 Set Temperature Lever at Detent to the Right o f Cold
2 Set Selector Lever at A / C
3. Set Blower Switch on High
4. O p e n Doors and Hood
5 W a rm Engine
6 Run Engine at ld le( Except 0 6 M odels)
1000 RPM ( C -K 0 6 Models)
Feel For A ir Flow A t Heater And A / C Outlets
| Not Hitting I
Adjust Door
Some or All A ir Flow From Heater
Outlet
Check M ode Door O peration-R epair,
A ir Flow From
A / C O utlets O n ly
Engaged or Cycling
Check Visually For Compressor Clutch O peration
______________________
I
______________________
O ff All the Time
NOTE
THIS SYSTEM DOES N O T H A V E A SIG H T GLASS. UNDER N O
CIRCUMSTANCES SHOULD A SIG H T GLASS BE INSTALLED
I
Feel Liquid Line Before Expansion Tube
---1-------
Check Compressor Hot Lead W ire W ith Test
Light or Place a Jumper W ire From The
Compressor to The Positive ( +) Terminal of
The Battery.
I_________________
Cold
W a rm l
Restriction in High Side of System.
Visually Look For Frost Spot to
Locate Restriction, Repair, Evacuate
Charge and Check The System
I
System
( O K .)
Feel Evaporator Inlet and Accumulator Outlet Pipes
Pipes same Temperature or
Outlet Colder Than Inlet
-----------------1------------------
Install the Thermometer in A / C O utlet and
Check Performance-See Performance Test
and Performance Data O utlined Earler in
This Section
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Inlet Pipe Colder
Than Outlet Pipe
T
Leak Check System-Repair Leak If No
Leak is Found, Check Expansion Tube
For Plugged Filter Evacuate and Charge
System. Check Inlet & O utlet Pipe Temperatures.
| N ot Engaged |
A p p ly External G round to Compressor,
if Clutch is Still not Engaged , Replace
Compresor Clutch - See the
O veraul Manual j
System
( O K . )
Engaged
Check For Blown M ain Fuse
I
Check For O p e n Circuit
at the Follow ing t
O utlet Temperature Satisfactory or
too cold - See Performance Data
Outlet Temperature High -
See Performance Data
Change Blower Speed To Low,
and O bserve Accumulator and
Evaporator Pipes For Frost.
Check Accumulator Pressure
( See Performance Data)
1
Pipes Still Cold and
W arm as A b ove
Pipes Same Temperature ( Cold)
or O utlet C older Than Inlet
Discharge Thermostatic
Pressure Switch
Switch
Lov
High To Norm al
N o Frost
I
System
(OK.)
Frost
Defective Thermostatic
Switch
I
Replace
I
System
( O K .)
Plugged Expansion Tube.Repair
or Replace and Evacuate, Charge
and Check System.
I
System
( O K .)
Replace Expansion Tube
and Evacuate, Charge and
Check System
I
System
(O K .) -
System
( O K .)
Check Refrigerant Pressure
at High Side Fitting
( A t Pressure Switch)
r
r
D efective
Switch
I
Replace
I
System
( O K .)
Check Compressor Cycling
O n Continuously Cycles on and O ff
Check For Missing Expansion Tube
| M issing""}1 ^
Install Expansion Tube, Evacuate,
Charge and Check System.
In Place
r
System
( O K.)
Check Compressor
Inlet Screen
I
Defective Thermostatic Switch
Replace
l
System
( O K .)
Plugged
T
Clean
| A b o ve 50 PSIG _ ___
Jump Switch
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Compressor Runs
i
D efective Switch
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Leak Check System,
Replace Switch, Evacuate,
Charge and Check System. I
System
( O K .)
Below 50 PSIG
Lost Charge -
Leak Test and
Repair. Evacuate,
Charge and Check System,
i
System
( O K .)
Repair or Replace Screen, E vacuate,
C harge and Check System,
i
System
( O.K.)
System O ver-C h arg ed.P urge,
Evacuate, Charge and Check System,
i
System
( O K .)
Fig. 100--lnsufficient Cooling Diagnosis-C-K Four-Season System
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