Chevrolet 1980 Light Duty Truck Service Manual page 59

Restriction in High Side of System.
V isually Check for Frost Spot to Locate
Restriction. Repair as Necessary.
I
Evacuate & Charge
I
System
(O.K.)
RUNS CONTINUOUSLY
WITHIN LIMITS
Disconnect Blow er W ire a n d Check For
Cycling O ff at 138-193 kPa (20-28 PSD
PRESSURE FALLS
BELOW 20 PSI
Defective Pressure
S w itch
I
Replace. *Do N ot Discharge
System. There is a Schrader
Valve in the Fitting
I
System
(O.K.)
AMBIENT TEMP.
A/C
PICK-UP
OUTLET
TEMP.
SUBURBAN
OUTLET TEMPERATURE
W ITHIN LIMITS
System
(O.K.)
MISSING
T
Install Expansion Tube
i
Evacuate & Charge
System
(O.K.)
SERVICE DIAGNOSTIC PROCEDURE
INSUFFICIENT COOLING — A/C SYSTEM S W ITH CYCLING CLUTCH — EXPANSION TUBE
MOVE TEMP. LEVER RAPIDLY BACK AND FORTH
FROM HOT TO COLD. LISTEN FOR DOOR HITTING
This System Does Not Have a Sight Glass. U nder No
C ircum stances Should a Sight Glass Be Installed
Feel Liquid Line Before Expansion Tube
INLET PIPE AND OUTLET
PIPE SAME TEMPERA­
TURE OR OUTLET
COLDER THAN INLET
Install Gage Set and Check Com pressor
Cycling Press,
i
ON at 282.6-351.6 kPa [41-51 PSD
OFF at 138-193 kPa (20-28 PSD
CYCLES WITHIN LIMITS
CYCLES OFF AT 138-193
kPa (20-28 PSI) OR DOES
NOT PULL DOWN TO
PRESS
Install Therm om eter in A C O utlet and
Check Performance
1. SET TEMP. LEVER TO FULL COLD
2 SET SELECTOR LEVER TO MAX AC
3. SET BLOWER SWITCH ON HI
4 CLOSE DOORS AND WINDOWS
5. RUN ENGINE AT 2000 R.P M
6. USE AUX. FAN IN FRONT OF GRILL
21°C 27° C 32° C 38° C
(70° F) (80°F)
(90°F) (100° F)
5-8°C
5-8°C 6-10°C 6-1 f C
(41-47) (41-47) (42-50) (43-57)
6-9°C 6-9°C
10-14°C 12-17°C
(42-48) (42-48)
(50-58) (54-62)
OUTLET TEMPERATURE
HIGH AS PER CHART
Check Com pressor Cycling
ON CONTINUOUSLY
* ' Discharge System and Check For
M issing Expansion Tube
Repair or Replace Screen
I
Evacuate & Charge
System
(O K )
C hart 1 B-3--Pressure C ycling CCOT System D iagnosis
(PRESSURE SENSING)
AT EACH END
Feel Evaporator Inlet and Outlet Pipes
CYCLES HIGH OR LOW
-------- r - -------
OR OFF BELOW 20 PSD
43 °C
(11 0F)
6-1 f C
(43-51)
14-19°C
(57-67)
IN PLACE
T
Check Com pressor Inlet
Screen
_____ I _ _____
System Over Charged
I
Evacuate & Charge
I
System
(O.K.)
AIR C O N D ITIO N IN G
(ON ABOVE 51 PSI
Defective
Pressure
Switch
i
Replace
*Do Not Discharge
System, There
Is a Schrader
System
(O K )
CYCLE ON AND OFF OR
REMAINS OFF FOR LONG
PERIOD OF TIME
I
Discharge System and
Check for Plugged Expansion Tube
i
Replace
i
Evacuate & Charge
System
(O.K.)
LIG H T TRUCK S E R V IC E MANUAL
1B-13