Chevrolet 1980 Light Duty Truck Service Manual page 65

NO AIR FLOW
CHECK DEFROSTER OUTLETS FOR AIR FLOW
(If in d o u b t as to High o r L o w air flo w
set selector on DEF w hich is High and
compare. Reset selector on Heater)
NO OR LOW AIR FLOW
CHECK HEATER OUTLET AIR FLOW
( If in dou bt, switch fan
switch fro m Hi to Lo)
-----------------1
CHANGE IN AIR FLOW |
NORMAL AIR FLOW
.........."1----------
Check heater o u tle t tem perature
w ith 220° F range therm om eter.
(approxim ate o u tle t air tem peratures)
O utlet A ir 145
A m bient A ir 0
NORMAL TEMPERATURE
Remove all obstructions under fro n t seat.
Car does n o t b uild up heat - operate vent
co ntro ls and see th a t the air vent doors
close c o m p lete ly, if not, adjust.
LOW TEMPERATURE
(Check th e system tem perature a fte r re­
pairing the item checked to com plete the
diagnosis.)
Check coolant level; if lo w , f ill. Look for
or feel all radiator and heater hoses and
connections fo r leaks. Repair or replace.
Check the ra d iato r cap fo r damage and re­
place if required.
Check heater and ra d iato r hoses fo r kinks
straighten and replace as necessary.
Check tem perature d oo r fo r max heat po­
sition. A djust if necessary.
| H E A T ER CORE
| Feel tem peratures o f heater in le t and o u tle t hoses. |
I WARM INLET AND OUTLET HOSES [
Check engine therm ostat.
HOT INLET AND WARM OUTLET HOSES
Check pulleys, b elt tension, etc., fo r p ro ­
per operation. Replace or service as neces­
sary.
_ _
Remove hoses fro m heater core. Reverse
flu sh w ith tap water. If plugged, repair or
replace.
P osition th e c o n tro ls so th a t the:
Tem perature lever is on fu ll heat.
Selector o r heater lever is on Heater.
Fan sw itch is on Hi.
CHECK BYPA SS DOOR OUTLET FOR AIR FLOW |
----
150 155 165
25 40 75
Check heater o u tle t fo r o b s tru c tio n - re­
move.
Check m o to r voltage at closest m o to r line
c o nnection w ith a vo ltm e te r.
UNDER 10 VOLTS
Check b a tte ry vo lts - under 10 volts,
recharge then recheck m o to r voltage.
Check w irin g and connections fo r
under 10 vo lts fro m m o to r to fan
sw itch. Repair o r replace last p o in t
o f under 10 v o lt reading.
A p p ly external ground, (jum per w ire) to
m o to r case. IN C R E A S ED A IR FLOW -
repair ground.
|
SAME A l R FLO W - remove m o to r and
check fo r o b s tru c tio n in system o pen­
ing. I f none, REPLACE M O TO R . I f
o bs tru ctio n , remove material and re­
install m o to r.
i :.............
I
AIR C O N D IT IO N IN G
| Adjust by- pas s for no air flow.
| HIGH AIR FLOW |
A djust d efroster d o o r fo r lo w air flo w .
LITTLE OR NO CHANGE IN AIR FLOW
LOW OR NO AIR F L O w |
Check s h u to ff doo r p o sitio n fo r fu ll
system air flo w . A d ju st if necessary.
LOW AIR FLOW
FUSE B LO W N - replace fuse.
A IR FLOW - system okay.
OVER 10 VOLTS
Remove p ositive lead fro m m o to r and
replace fuse.
FUSE R E M A IN S O K - remove m o to r
and check fo r o b s tru c tio n in system
opening, if none, REPLACE M O TO R .
If o b s tru c tio n , remove material and
re -in stall m o tor.
BLOWS FUSE - check fo r shorted
w ire in b low er e lectric c irc u it -
See Heater C irc u it Diagnostic C hart.
1B-19
| NO AIR FLOW
| CHECK FUSE
BLOWS FUSE
I
FUSE OK
FUSE O K - See Heater C irc u it
Dia gnostic Chart.
LIGHT TRU CK S E R V IC E M ANUAL