GMC 4000 Series Service Manual page 68

3. Apply coat of weatherstrip adhesive to seal
and seal surfaces of door as directed by manu­
facturer of adhesive. Directions for application
are usually found on adhesive container.
4. Position seal around perimeter of door,
VENTILATION
A single grilled intake at front center of cab
(fig. 26) perm its outside air to enter plenum cham­
ber located between the cab outer and inner panels.
From the plenum chamber, outside air can be di­
rected into cab interior through opening at front of
driver and through opening at front of passenger.
When heater is used, the outside air enters heat­
ing system through the right side opening.
The outlet located ahead of driver is opened
and closed manually by control knob on dash. The
control knob pushed inward closes outlet door and
pulling out on knob opens outlet door. A spring-
loaded door prop retains door snug in either the
fully opened or closed positions. A rubber seal
around perim eter of outlet door provides positive
Figure 27— Outside Air Intake
Necessary equipment for efficient and safe
replacement of cab consists of a chain hoist (1-ton
minimum capacity), a sling having padded hangers,
and two or more support blocks to rest cab on
when it is removed from chassis.
NOTE: A wood 4 x 4 , 7 ^ feet long positioned
G M C S E R V I C E M A N U A L
making sure corners of seal engage respective
corners of door.
and weatherstrip. Tighten clip screws firmly but
be careful not to tear weatherstrip.
CAB VENTILATION A N D HEATING
sealing of outlet. Seal, which is glued to door, can
be readily replaced if necessary.
CONTROL ADJUSTMENT (DRIVER"S SIDE)
ly in, the air outlet door should close snug to out­
let opening.
knob in this position, loosen screw at control con­
duit clamp above door which will allow com pres­
sion spring within door telescopic prop to force
door tight to opening. Retighten clamp screw after
making adjustment.
control type (fig. 28) and is serviced in same man­
ner as M Air-Flow Heater" described previously
under "Conventional Model Cabs."
CAB REPLACEMENT
through cab door openings with a hoist chain at­
tached securely to each end can be used. However,
means of protecting top of cab from chain must be
provided. Also, be sure to provide padding at points
where beam contacts cab openings and carefully
position beam to assure proper cab support.
5. Install screw-retained clips (fig. 26) to door
NOTE: Refer to inset of figure 27.
When control knob on dash is pushed complete­
If door is not seated completely with control
HEATING
The heater is of the water valve temperature
Sec. 1
Page 61
TILT CAB