Performance Data; Four-Season Air Conditioning; Roof Mounted Air Conditioning - Chevrolet 10 1971 Series Chassis Service Manual

25—
Fig. Compressor Connector Block - Typical
compare the performance of the system being tested with
the standards below:
1. Doors and windows closed.
shade.)
2. Hood up and engine exhaust suitably ventilated.
3. Vehicle in NEUTRAL with engine running at 2000 rpm.
4. Air Conditioning controls set for -
• Maximum cooling.
Four-Season System - Upper lever on "Inside"
and temperature lever at "Cold."
GM Chevrolet System - Right knob at "City."
• High blower speed.
5. Gauge set installed.
6. System settled out (run-in approximately 10 minutes).
7. A thermometer placed in front of vehicle grille and
another in the right hand dash outlet (Four-Season
and GM Chevrolet Systems) or right rear outlet
(Roof-Mounted Systems).

PERFORMANCE DATA

The following Performance Data define normal opera­
tion of the system under the above conditions. Relative
(Vehicle inside or in
HEATER AND AIR CONDITIONING 1A-17
humidity does not appear in the tables because after run­
ning the prescribed length of time on recirculated air
and maximum cooling, the relative humidity of the air
passing over the evaporator core will remain at approx­
imately 35% to 40% regardless of the ambient tempera­
ture or humidity.
Should excessive head pressures be encountered at
higher ambient temperatures, an 18" fan placed in front
of the vehicle and blowing into the condenser will provide
the extra circulation of air needed to bring the pressures
to within the limits specified.
Higher temperatures and pressures
NOTE:
will occur at higher ambient temperatures.
areas of high humidity it is possible to have
thermometer and gauge readings approach but
not reach the figures listed in the performance
tables and still have a satisfactorily operating
unit. However, it is important to remember that
low pressure has a direct relationship to nozzle
outlet temperature.
will gradually form on the evaporator fins, re­
stricting airflow into the passenger area and
resulting in insufficient or no cooling.

Four-Season Air Conditioning

(Refrigerant Charge - 3 Lbs. - 4 Oz.)
Temperature of
Air Entering 70°
Condenser
Engine rpm
Compressor Head 145-
155
Pressure
Evaporator Pressure
at POA See Chart Under Evaporator
Discharge Air 38-
Temp, at Right 41
Hand Outlet

Roof Mounted Air Conditioning

(Refrigerant Charge - 4 lbs.-8 oz.)
Temperature of
Air Entering 70°
Condenser
Engine rpm
Compressor 155-
165
Head Pressure*
Suction Pres­
10
sure psi*
Discharge Air 37-
44
Temperature*
In
If pressure is too low, ice
80° 100° 110° 120°
2000
185- 200- 215- 255-
195 210 225 265
Dependent Upon Altitude
Control Valve (POA)
38- 40- 41- 43-
41 43 44 46
80° 90° 100° 110° 120°
2000
165- 175- 200- 240-
175 185 240 250
10 10 10 14
37- 38- 41- 46- 49-
44 45 48 53
10-30 CHEVROLET TRUCK SERVICE MANUAL
285-
295
48-
51
275-
285
18
56