Chevrolet 70 Series 1970, Service Manual

Page: 133 / 841

CAB AND BODY MOUNTINGS 1-102
"TEMP" le v e r can be u sed to vary tem perature of
a ir conditioning output by m ixing warm and cool
a ir in sy ste m . When using the a ir conditioning s y s ­
tem , do not m ove "HTR" knob a ll the way to the
"HTR" p osition a s th is w ill d irec t a ll cool a ir to
the floor through main h eater co re and defeat
cooling effect of a ir conditioning. If a ir d irected
through h eater ducts to cab floor is d e sir e d , m ove
"HTR" knob part way betw een "HTR" and "DEF."
5. The "FAN" sw itch con trols the speed of the
blow er m otors. The four sw itch p o sitio n s a r e "OFF"
(lev e r down), "Low," "Medium," and "High” (lev er
up). The blow er is used to m ove a ir for the heater,
d e fr o ster, s le e p e r com partm ent heater, and air
conditioning sy ste m .
6
. D irection of a ir flow from A /C ou tlets
mounted on cen ter co n so le can be controlled by
changing p osition of d e fle c to r s. D irection of a ir
flow from A /C outlet d irectly in front of driver
can be controlled by repositioning outlet d eflecto r.
The exhaust sy ste m should be in sp ected for
lea k s and m issin g or dam aged p arts each tim e the
v e h icle is lubricated.
OPERATING AIR CONDITIONING SYSTEM
IMPORTANT: B e su r e A /C le v e r is in the
"OFF" p osition to reduce e le c tr ic a l load on battery
when starting engine.
1. With engine running, m ove A /C control
le v e r to "ON" p osition . B low er w ill autom atically
op erate at low sp eed .
2. Move "AIR" le v e r to "OUTSIDE." "HTR"
le v e r between "HTR" and "DEF." and "TEMP"
le v e r to "COLD."
3. P la c e blow er control sw itch to high sp eed
and open cab entrance door fr e s h - a ir ventilator
fo r a few m inutes to exp el w arm air from cab.
4. When cab begins to co o l, c lo se cab door
fr e s h -a ir ventilator tightly and m ove "AIR” le v e r
betw een "OUTSIDE" and "RECIR" to provide de­
s ir e d m ixture of both recir cu la ted and outside a ir .
A s required, "TEMP" le v e r can be s e t between
"HOT" and "COLD" p o sitio n s to allow m ixing of
hot and cool conditioned a ir a s required for co m ­
fortable sy ste m outlet tem p eratu res.
OPERATING HEATING SYSTEM ONLY
1. For heating only, m ove A /C le v e r to "OFF"
and "AIR" le v e r to "OUTSIDE." P o sitio n "TEMP”
le v e r as required for com fortable tem perature of
incom ing cab a ir.
2. Should defogging of w indshield be required,
open door fr e sh a ir ventilator slig h tly , p la ce "HTR"
le v e r to "DEF" and operate blower at high speed.
3. For warm w eather ventilation, le s s air
conditioning, p la ce A /C le v e r on "OFF," "AIR"
le v e r on "OUTSIDE." "HTR" lev er on "HTR."
"TEMP" le v e r on "COLD," and then p la ce blow er
sw itch on "High Speed." A ir flow w ill be d irected
through h eater ou tlets and not A /C o u tlets.
SLEEPER CAB HEATER
M odels with a sle e p e r cab have an auxiliary
heating sy ste m . There are two controls for o p er­
ating th is sy ste m . The control knobs are located
to the right of the d river, rearw ard of the main
heating and a ir conditioning control panel on the
c o n so le . One knob con trols the volum e of a ir flow
into the sle e p e r com partm ent and the other con­
tr o ls the tem perature of the a ir , F or g rea ter v o l­
um e an d /o r higher tem p eratu re, p u ll knobs out.
F or l e s s volum e a n d /o r low er tem p eratu re, push
knobs in.
WARNING: Before sleeping in cab,
make sure that adequate ventilation will
be provided.
CONVENTIONAL CAB MODELS
(R efer to F ig u res 5 and
6
)
1. With the engine running:
a. P la c e "AIR COND." control le v e r to "ON."
NOTE: B low er m otor w ill autom atically o p er­
ate at low sp eed .
b. P la c e "AIR" control le v e r to "A/C."
c. S e lect blow er speed.
NOTE: For rapid cool-dow n, p la ce blow er
control sw itch le v e r to "High-Speed" p o sitio n .
A lso open windows fo r a m inute o r two to ejqpel
w arm a ir from cab.
2. A fter d esired tem perature in cab is obtained
m ove "AIR" le v e r to "NORMAL" p o sitio n , which
w ill gen erally provide an id ea l m ixture of both r e ­
circu la ted a ir and outside a ir for m axim um co m ­
fort.
3. If d esired , the "TEMP” le v e r can a lso be
m oved to any d egree tow ards the "HOT" p osition ,
to provide m axim um com fort by coolin g, dehumid-
ifying, then re-h ea tin g the a ir flowing through the
sy ste m .
NOTE: F or heating only, le a v e "AIR COND."
le v e r in "OFF" p o sitio n and m ove "AIR" le v e r to
"OUTSIDE," then operate sy ste m a s d escrib ed on
the follow ing page.
NOTE: The a ir flow d irection from any one
of the dash o u tlets can be con trolled by positioning
of outlet inner d eflecto r. The inner d eflector can
a lso b e o sc illa te d to com p letely c lo s e the outlet if
d e sir e d . To c lo s e off any one of the o u tlets w ill
in c r e a se the flow from rem aining open o u tlets.
The sm a ll ou tlet door at b a se of distributor duct
can be opened if d e sir e d by pulling downward on
door tab.
OPERATING HEATING SYSTEM ONLY
A ll four control knobs a r e in "OFF" p osition
when p laced to extreme; left sid e of control panel.
"DEFROST" knob con trols flow of a ir to the
w indshield d efro ster ducts. With knob a ll the way
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL