Chevrolet 1977 light duty truck, Service Manual

Page: 61 / 861

M e t a l T u b e O . D .
T h r e a d a n d
F i t t i n g S i z e
A l u m . T u b i n g
T o r q u e *
1 / 4 7 / 1 6 6
3 / 8 5 / 8
12
1 / 2 3 / 4 18
5 / 8 7 / 8
2 4
3 / 4
1 - 1 / 1 6 30
* F o o t P o u n d s
blower m otor m a y be operated in d e p e n d e n t o f the front
A / C blower m o to r and without the cooling function.
DASH M O U N T E D U N IT (M O T O R H O M E
C H A SS IS U N IT S )
This system is self contained and is m ounted below
the dash by the body m anufacturer. System controls
consist o f an A IR knob and T E M P knob located in the
center o f the unit face plate (fig. IB-16).
Air Knob
T u rn in g the AIR knob clockwise operates a three
speed (L O W -M E D -H I) blower motor.
Tem p Knob
This knob is used to control the degree o f cooling
desired. Fully clockwise at CITY provides m axim um
cooling, while turning the knob to H IW A Y provided
ad e q u a te cooling for highway operation.
N O T E : Reduced cooling could be encountered
w h en operating at highway speeds with the controls
at the CITY setting. The heater must be fully off to
o b ta in m ax im u m cooling.
R E F R IG E R A N T LIN E C O N N E C T IO N S
"
0
"
Rings
Always replace the " O " ring w hen a connection has
been broken. W hen replacing the " O " ring, first dip it in
clean re frig e ratio n 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 p rocedures are necessary for both removal and
installation.
Removal
Fig. IB-17- Hose Clamp Connections
1. Carefully, with a sh arp 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 o f hose.
CAUTION: Use only approved refrigeration
hose. N ever use heater hose. Use extereme care
not to nick or score the sealing beads when
cutting o f f the hose. C utting 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 f a 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
arm s 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 . T he 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 u rth er tightening may d a m a g e the hose.