Chevrolet 1977 light duty truck Service Manual page 61

T h r e a d a n d
M e t a l T u b e O .D .
F i t t i n g S i z e
1 / 4
3 / 8
1 / 2
5 / 8
3 / 4
1 - 1 / 1 6
* F o o t P o u n d s
blower m otor m ay be operated in d ep end en t o f the front
A / C blower m otor and without the cooling function.
DASH M O U N T E D U N IT (M O T O R HO M E
CH A SS IS U N IT S )
This system is self contained and is mounted below
the dash by the body m anufacturer. System controls
consist o f an AIR knob and T E M P knob located in the
center o f the unit face plate (fig. IB-16).
Air Knob
T u rning the AIR knob clockwise operates a three
speed (L O W -M E D -H I) blower motor.
Temp Knob
This knob is used to control the degree o f cooling
desired. Fully clockwise at CITY provides maximum
cooling, while turning the knob to H IW AY provided
adequate cooling for highway operation.
N O T E: Reduced cooling could be encountered
w hen operating at highway speeds with the controls
at the CITY setting. The heater must be fully off to
ob tain m axim um cooling.
R E FR IG E R A N T LINE C O N N E C T IO N S
0
Rings
" "
Always replace the " O " ring when a connection has
been broken. W hen replacing the " O " ring, first dip it in
clean re frigeration oil. Always use a backing wrench on
" O " ring fittings to prevent the pipe from twisting and
d a m a g in g the " O " ring. D o not overtighten. Correct
torque specifications are as follows:
CAUTION: Where steel to alum inum connec­
tions are being made, use torque fo r alum inum
tubing.
Hose Clam ps
W h e n hose clamp connections are encountered,
special procedures are necessary for both removal and
installation.
Removal
A l u m . T u b i n g
T o r q u e *
7 / 1 6 6
5 / 8
12
3 / 4
18
7 / 8
24
30
Fig. IB-17- Hose Clamp Connections
1. Carefully, with a sharp knife, make an angle cut
in the hose as shown in Figure IB -17. This should loosen
the hose so that it may be worked off the fittings.
2. Cut off slit end of hose.
CAUTION: Use only approved refrigeration
hose. Never use heater hose. Use extereme care
not to nick or score the sealing beads when
cutting o ff the hose. Cutting the hose lengthwise
m ay result in this problem.
Installation
1. Coat tube and hose with clean refrigeration oil.
2. Carefully insert hose over the three beads on the
fitting and down as fa r as the fourth, or locating bead.
Hose must butt against this fourth bead.
CAUTION: Use no sealer o f any kind.
3. Install clamps on hose, hooking the locating
arms over the cut end o f the hose.
4. Tighten the hose clamp screw to 35-42 in. lbs.
torque. DO N O T R E T O R Q U E . The clamp screw torque
will normally decrease as the hose conform s to the force
o f the clamp. The screw should be retorqued only if its
torque falls below 10 in. lbs. In this case, retorque to 20-
25 in. lbs. F urther tightening may dam age the hose.