GMC 4000 Series Service Manual page 89

Sec. 1
Page 82
AIR CONDITIONING
auxiliary fan air stream to measure wet bulb
temperature.
6. Connect engine tachometer.
7. Open all air outlets below dash.
8. Locate a calibrated thermometer in center
outlet. Sensing bulb must not touch metal.
EVAPO RATO R
G A U G E HIGH
PRESSURE H O SE
G A U G E LO W
PRESSURE H O SE
G A U G E H O S E C O N N E C T IO N S A T C O M P R E S S O R
G M C S E R V I C E M A N U A L
SU C TIO N THROTTLING VALVE
C A r M M O i u n
VALVE
Figure 11 — H o o k -U p of G a u g e s a n d E vacuating Pum p
9. Place transmission lever in "Neutral,"with
parking brake on.
10. Start engine and set "AIR" lever at "OUT­
SIDE," "TEMP" lever full left for maximum cooling
and blower switch at high blower speed.
11. Set engine speed at 2000 rpm.
C O M P R E SSO R
■FROM RECEIVER DEHYDRATOR
LO W PRESSURE
TO SYSTEM
SU C TIO N LINE
TO V A C U U M
PUMP, REFRIGERANT,
OR REFRIGERANT OIL
G A U G E SET
TO C O N D E N SE R
V A C U U M PUMP
H IG H PRESSURE
TO SYSTEM
D ISC H AR G E LINE