Vintage 1967-72 CHEV PICK-UP Specifications

an ISO 9001:2008 Registered Company
1967-72 Chevy Pickup
without Factory Air
751170
18865 Goll St. San Antonio, TX 78266 ph: 210-654-7171 fax: 210-654-3113
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Table of Contents
1.
2.
3.
4.
5.
6.
Cover
Table of Contents
Packing List/Parts Disclaimer
Information Page
Wiring Notice
Engine Compartment
Figure 1
7. Condenser Assembly, Compressor & Bracket, Passenger
Compartment
Figure 2
8. Defrost Duct and Louver Installation
Figures 3, 3a & 3b
9. Fresh Air Cap and Firewall Cover Installation, Bracket and Evaporator
Hardline Installation
Figures 4 & 5
10. Bracket and Evaporator Hardline Installation (Cont.)
Figure 6
11. Evaporator Installation
Figures 7 & 7a
12. Drain Hose Installation, Lubricating O-rings, A/C Hose Installation
Figures 8 & 9
13. Heater Hose & Heater Control Valve Installation
Figure 10
14. A/C & Heater Hose Routing
Figure 11
15. Final Steps
Figures 12 & 12a
16. Control Panel & Duct Hose Routing
Figure 13
17. Wiring Diagram
18. Gen IV Wiring Connection Instructions
19. Operation of Controls
20. Troubleshooting Information
21. Troubleshooting Information (Cont.)
22. Driver/Passenger Side Louver Template
23. Center Louver Template
24. Evaporator Kit Packing List
901149 REV D 7/30/14, INST 67-72 CHEVY PICKUP wo AC EVAP KIT PG 2 OF 24
2
Packing List
Evaporator Kit (751170)
No.
1.
2.
Qty.
1
1
Part No.
Description
744005
791170
Gen IV 3-Vent Evaporator Sub Case w/ 204 ECU
Accessory Kit 67-72 Chevy Pickup without A/C
** Before beginning installation, open all packages and check contents of shipment.
Please report any shortages directly to Vintage Air within 15 days. After 15 days,
Vintage Air will not be responsible for missing or damaged items.
1
Gen IV 3-Vent
Evaporator Sub Case
w/ 204 ECU
744005
2
Accessory Kit
791170
3
NOTE: Images may not depict actual parts and quantities.
Refer to packing list for actual parts and quantities.
901149 REV D 7/30/14, INST 67-72 CHEVY PICKUP wo AC EVAP KIT PG 3 OF 24
Important Notice—Please Read
For Maximum System Performance, Vintage Air Recommends the Following:
Heater Hose (Not Included With This Kit):
Heater hose may be purchased from Vintage Air (Part# 31800-VUD) or your local parts retailer.
Routing and required length will vary based on installer preference.
Bolts Passing Through Cowl and/or Firewall:
To ensure a watertight seal between the passenger compartment and the vehicle exterior, for all
bolts passing through the cowl and/or firewall, Vintage Air recommends coating the threads with
silicone prior to installation.
Safety Switches:
Your Vintage Air system is equipped with a binary pressure safety switch. A binary switch disengages
the compressor clutch in cases of extreme low pressure conditions (Refrigerant Loss) or excessively
high head pressure (406 PSI) to prevent compressor damage or hose rupture. A trinary switch
combines Hi/Lo pressure protection with an electric fan operation signal at 254 PSI, and should be
substituted for use with electric fans. Compressor safety switches are extremely important since an
A/C system relies on refrigerant to circulate lubricant.
Service Info:
Attention: The following system components are capped: Compressor, evaporator, condenser & drier.
Caps may be under pressure with dry nitrogen. Be careful removing caps. Do not remove caps prior to
installation. Removing caps prior to installation will cause components to collect moisture and lead to
premature failure and reduced performance.
Evacuate the system for 35-45 minutes with system components (Drier, compressor, evaporator and
condenser) at a temperature of at least 85° F. On a cool day, the components can be heated with a heat
gun OR by running the engine with the heater on before evacuating. Leak check and charge to
specifications.
Vintage Air Systems Are Designed to Operate With R134a
Refrigerant Only! Use of Any Other Refrigerants Is a Fire Hazard and
Could Damage Either Your Air Conditioning System or Your Vehicle.
Use of Any Other Refrigerants Will Void All Warranties of the Air
Conditioning System and Components. Use of the Proper Type and
Amount of Refrigerant Is Critical to Proper System Operation. Vintage
Air Recommends Our Systems Be Charged By Weight With a Quality
Charging Station or Scale.
Refrigerant Capacity for Vintage Air Systems:
(For other systems, consult manufacturer’s guidelines)
R134a System
Charge with 1.8 lbs. (1 lb., 12 oz.) of refrigerant.
Lubricant Capacities:
New Vintage Air-supplied Sanden Compressor: No additional oil needed (Compressor is
shipped with proper oil charge).
All Other Compressors: Consult manufacturer (Some compressors are shipped dry and will
need oil added).
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4
Important Wiring Notice—Please Read
Some Vehicles May Have Had Some or All of Their Radio Interference Capacitors Removed.
There Should Be a Capacitor Found At Each of the Following Locations:
1. On the positive terminal of the ignition coil.
2. If there is a generator, on the armature terminal of the generator.
3. If there is a generator, on the battery terminal of the voltage regulator.
Most alternators have a capacitor installed internally to eliminate what is called “whining” as
the engine is revved. If whining is heard in the radio, or just to be extra cautious, a radio
interference capacitor can be added to the battery terminal of the alternator.
It is also important that the battery lead is in good shape and that the ground leads are not
compromised. There should be a heavy ground from the battery to the engine block, and
additional grounds to the body and chassis.
If these precautions are not observed, it is possible for voltage spikes to be present on the
battery leads. These spikes come from ignition systems, charging systems, and from
switching some of the vehicle’s other systems on and off. Modern computer-operated
equipment can be sensitive to voltage spikes on the power leads, which can cause unexpected
resets, strange behavior, and/or permanent damage.
Vintage Air strives to harden our products against these types of electrical noise, but there is
a point where a vehicle’s electrical system can be degraded so much that nothing can help.
Radio interference capacitors should be available at most auto and truck parts suppliers. They
typically are cylindrical in shape, a little over an inch long, a little over a half inch in diameter,
and they have a single lead coming from one end of the cylinder with a terminal on the end of
the wire, as well as a mounting clip which is screwed into a good ground on the vehicle. The
specific value of the capacitance is not too significant in comparison to ignition capacitors that
are matched with the coil to reduce pitting of the points.
• Care must be taken, when installing the compressor lead, not to short it to ground.
The compressor lead must not be connected to a condenser fan or to any other
auxiliary device. Shorting to ground or connecting to a condenser fan or any other
auxiliary device may damage wiring, the compressor relay, and/or cause a
malfunction.
• When installing ground leads on Gen IV systems, the blower control ground and ECU
ground must be connected directly to the negative battery post.
5
• For proper system operation, the heater control valve must be connected to the
ECU.
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Engine Compartment
NOTE: Before starting the installation, check the function of the vehicle (horn, lights, etc.) for proper
operation, and study the instructions, illustrations & diagrams.
Perform the Following:
1. Disconnect battery.
2. Drain and remove radiator (retain).
3. Remove heater blower assembly and OEM heater hoses (discard).
NOTE: To remove the OEM heater blower assembly (under hood) and the air distribution system
(under dash), the factory manual recommends that the right inner fender be removed for accessibility.
FIGURE 1
Figure 1
OEM Heater
Blower
Assembly
6
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Condenser
Assembly and Installation
1. Refer to separate instructions included with the condenser kit to install the condenser.
2. Binary switch installation (Refer to condenser instructions).
Compressor and Brackets
1. Refer to separate instructions included with the bracket kit to install the compressor and bracket.
Passenger Compartment
Perform the Following:
1. Remove the glove box door (retain) and glove box (discard).
2. Disconnect all wires and cables from control panel and radio.
3. Remove all hoses and ducting from defrost ducts (See Figure 2, below).
4. Remove OEM heater assembly.
OEM Defrost
Duct Assembly
Glove Box
Door
Radio
Control
Panel
Figure 2
OEM Heater Assembly
& Related Ducting
7
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Defrost Duct
and Louver Installation
1. Install S-clips on defrost duct hose adapters, and attach to OEM defrost ducts as shown in Figure 3, below.
2. Install center louver into dash as shown in Figure 3b, below. Use dimensions provided on Page 23. NOTE:
Center louver may need to be tapped to 1/4-20 to accept studs.
3. Install driver/passenger side louvers into dash as shown in Figure 3a, below. Use template provided on Page
22.
Hose
Adapter
Dash
Passenger Side
Oval Defrost
Adapter
49167-VCI
OEM Defrost
Ducts
(2) S-clips
Figure 3a
Ball
Louver
49053-VUL
(2) S-clips
Driver Side
Round Defrost
Adapter
49168-VCI
(2) 1/4-20 Nuts
w/ Star Washers
Figure 3
Dash
(2) 1/4” Flat
Washers
Figure 3b
(2) 1/4-20 X 1 ¾”
Studs
NOTE: Studs, nuts and washers are
packaged in bag with heater control
valve.
8
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Fresh Air Cap
& Firewall Cover Installation
1. Apply a 1/4” bead of silicone around the back side of the fresh air cap as shown in Figure 4, below.
2. Attach fresh air cap to firewall using a 1/4-20 x 1” bolt and washer (See Figure 4, below).
3. Apply a 1/4” bead of silicone around the back side of the firewall cover as shown below.
4. Install firewall cover onto firewall using (2) 1/4-20 x 1” hex bolts, (2) flat washers and (2) 1/4” nuts with star
washers in the OEM holes as shown below.
5. Use firewall cover as a template to drill (6) 3/16” holes in firewall, and then secure using #14 x 3/4” sheet
metal screws as shown below.
6. Using the firewall cover as a template, drill (2) 9/32” holes in the firewall as shown below.
7. Install grommets as shown below.
Drill
9/32” Hole
Silicone
1/4” Flat
Washer
Fresh Air
Cap
Silicone
Back Side
of Fresh Air
Cap
1/4-20 X 1”
Bolt
1/4” Flat
Washer
Back Side
of Firewall
Cover
648218
OEM
Hole
Large
Grommet
33137-VUI
1/4-20 X 1”
Bolt
3/8”
Grommet
33144-VUI
Grommet
33135-VUI
OEM
Hole
1/4-20 X 1”
Bolt
1/4” Flat
Washer
1/4” Nut w/
Star Washer
Figure 4
1/4” Nut w/
Star Washer
(6) #14 X 3/4”
Sheet Metal
Screws
Drill
9/32” Hole
Bracket & Evaporator Hardline Installation
1. On a workbench, install evaporator rear
bracket using (4) 1/4-20 x 1/2” hex
bolts.
2. Install hardlines with properly lubricated
O-rings (See Figure 9, Page 12, and
Figure 6, Page 10). NOTE: Wrap the
#10 fitting connections with press
tape (See Figure 6, Page 10).
3. Install evaporator front bracket onto
evaporator using (2) 1/4-20 x 1/2” hex
bolts, and tighten as shown in Figure 5,
below.
(2)1/4-20 X 1/2”
Hex Bolts
Figure 5
9
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Front
Evaporator
Bracket
644080
Bracket & Evaporator
Hardline Installation (Cont.)
ECU Module
(2) 1/4-20 x 1/2”
Hex Bolts
#6
O-ring
#6 Liquid Line
095002
(2) 1/4-20 x 1/2”
Hex Bolts
Rear
Evaporator
Bracket Assembly
644073
Hold With
This Wrench
Twist With
This
Wrench
Press Tape
NOTE: After Installing
#10 Suction Line, Wrap
All Exposed Metal
(Fittings & Tube)
With Supplied Press Tape.
Lubricate O-ring
(See Figure 9,
Page 12)
Figure 6
#10 O-ring
#10 Suction
Line
095003
#6 Liquid Line
095002
Heater Line
(Evaporator to Water Pump)
095004
Heater Line
(Evaporator to Intake)
#10 O-ring
095005
10
901149 REV D 7/30/14, INST 67-72 CHEVY PICKUP wo AC EVAP KIT PG 10 OF 24
Evaporator Installation
1. Lift evaporator unit up under the dashboard, and secure loosely to the firewall using (2) 1/4-20 x 1” hex bolts,
(2) flat washers and (2) 1/4” nuts with star washers (See Figure 7, below). NOTE: To ensure proper
drainage, it is very important that the evaporator is level, both left-to-right and fore-aft. Check for
level on the flat portions of the case around the drain, block the unit up, and then drill holes for
front bracket screws.
2. Secure the front evaporator mounting bracket to the cowl using (2) #14 x 3/4” hex sheet metal screws (See
Figure 7a, below).
3. Verify that the evaporator unit is level and square to the dash, and then tighten all mounting bolts. NOTE:
Tighten the bolt on firewall first, and then the front mounting bracket.
Drill (2)
3/16” Holes
(2)#14 x 3/4”
Sheet Metal
Screws
Inner Cowl
1/4”
Flat
Washer
Figure 7
1/4-20 x 1”
Hex Bolt
1/4-20 x 1”
Hex Bolt
Flat
Washer
1/4” Nut w/
Star Washer
View From
Passenger Side,
Inside of Cab
Figure 7a
11
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Drain Hose Installation
1. Locate evaporator drain on bottom of
evaporator case.
2. In line with drain, lightly make a mark on the
firewall. Measure 1” down and drill a 5/8”
hole through the firewall.
3. Install drain hose to bottom of evaporator unit
and route through firewall. Install 1/2” 90°
drain elbow onto drain hose.
1”
1”
Evaporator
Case
Drain
Hose
Figure 8
Lubricating O-rings
Male
O-ring Insert
#6 O-ring
#8 O-ring
#10 O-ring
Female Nut
For a proper seal of fittings: Install supplied
O-rings as shown, and lubricate with supplied
oil.
O-ring
Supplied Oil
for O-rings
NOTE: Standard torque specifications:
#6: 11 to 13 ft-lb.
#8: 15 to 20 ft-lb.
#10: 21 to 27 ft-lb.
O-ring Installs
Over Male Insert
to Swaged Lip
Figure 9
Twist With
This Wrench
Hold With
This Wrench
A/C Hose Installation
Standard Hose Kit:
1. Locate the #8 compressor A/C hose. Lubricate (2) #8 O-rings (See Figure 9, above) and connect the 135°
female fitting with 134a service port to the #8 discharge port on the compressor. Route the straight female
fitting to the #8 condenser hardline coming through the core support (See Figure 11, Page 14). Tighten each
fitting connection as shown.
2. Locate the #10 compressor A/C hose. Lubricate (2) #10 O-rings (See Figure 9, above) and connect the #10
135° female fitting with 134a service port to the #10 suction port on the compressor. Route the 90° female
fitting to the #10 evaporator (See Figure 10, Page 13, and Figure 11, Page 14). Tighten each fitting connection
as shown.
3. Locate the #6 evaporator A/C hose. Lubricate (2) #6 O-rings (See Figure 9, above) and connect the straight
female fitting to the #6 condenser hardline coming through the core support. Route the 90° female fitting to
the #6 evaporator (See Figure 10, Page 13, and Figure 11, Page 14). Tighten each fitting connection as shown.
Modified A/C Hose Kit:
1. Refer to separate instructions included with modified hose kit.
12
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Heater Hose and
Heater Control Valve Installation
1. Route heater hose from water pump to the heater line coming through the firewall as shown in Figure 10,
below. Secure using hose clamps. NOTE: A small amount of silicone spray will ease heater hose
installation.
2. Route heater hose from the intake to the heater line coming through the firewall as shown below. NOTE:
Install heater control valve in line with intake manifold (pressure side) heater hose, and secure
using hose clamps as shown. Also note proper flow direction.
3. Hose should protrude through the firewall cover slightly to close the gap between the aluminum line and the
firewall cover. Seal any remaining gap with RTV silicone.
O-rings
#10 Suction
Line
Liquid
Line
FRO
ME
TO W VAPORA
TO
ATER
PUM R
P
FRO
MH
TO E TR CNT
R
VAP
ORA L VLV
TOR
Heater
Hose
FRO
M
MAN INTAKE
IFOL
D
NOTE: Flow Direction Follows
Molded Arrow on Valve.
Figure 10
13
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901149 REV D 7/30/14, INST 67-72 CHEVY PICKUP wo AC EVAP KIT PG 14 OF 24
#6 Hose
096002
Tie Wrap
#10 Suction
Hose
096003
5/8” Heater
Hose
FRO
M
MA INTA
K
NIF
OLD E
#8 Discharge
Hose
096001
NOTE: Flow Direction Follows
Molded Arrow on Valve.
FRO
M
TO EVAPO
WA
TER RATO
PUM R
P
From Heater Control Valve
to Evaporator
14
Figure 11
#6 Drier/Core
Support
Hardline
095006
Heater Hose
(Heater Control
Valve/Intake)
Compressor
Safety Switch (Binary Type)
Screw-On Drier (Refer To
Condenser Instructions)
#8 Condenser/
Comp. Hardline
095007
NOTE: Vintage Air Systems Require
(2) 5/8” Hose Nipples (Not Supplied).
#6 Cond/Drier
Hardline
35056-LCG
A/C & Heater Hose Routing
Final Steps
1. Install duct hoses as shown in Figure 13, Page 16.
2. Route A/C wires (12 volt/ground/binary switch/heater valve) through 3/8” grommet as shown in Figure 12,
below.
3. Install control panel assembly.
4. Plug the wiring harnesses into the ECU module on the sub case as shown in Figure 13, Page 16 (Wire according
to wiring diagram on Pages 17 and 18).
5. Install new glove box using OEM screws (See Figure 12a, below).
6. Install glove box door.
7. Reinstall all previously removed items, including inner fender.
8. Fill radiator with at least a 50/50 mixture of approved antifreeze and distilled water. It is the owner's responsibility
to keep the freeze protection at the proper level for the climate in which the vehicle is operated. Failure to follow
antifreeze recommendations will cause heater core to corrode prematurely and possibly burst in A/C mode and/or
freezing weather, voiding your warranty.
9. Double check all fittings, brackets and belts for tightness.
10. Vintage Air recommends that all A/C systems be serviced by a certified automotive air conditioning technician.
11. Evacuate the system for a minimum of 45 minutes prior to charging, and perform a leak check prior to servicing.
12. Charge the system to the capacities stated on Page 4 of this instruction manual.
13. See Operation of Controls procedures on Page 19.
Wiring Harness
(Heater Control Valve)
Grommet
33144-VUI
Figure 12
Wiring Harness
(12 Volt/Ground/Binary Switch)
Figure 12a
Glove Box
496067
15
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Control Panel
and Duct Hose Routing
Passenger Side
Defrost Duct
2” X 12”
Plug
From
Control
Wiring
Harness
232002-VUA
Driver Side
Defrost Duct
2” X 24”
Plug
From
Wiring
Harness
232001-VUR
Center
Louver
2 ½” X 18”
Passenger Side
Louver
2 ½” X 36”
Driver Side
Louver
2 ½” X 48”
Figure 13
16
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Wiring Diagram
232007-VUR
TAN
ORA
BLK
AC ANNUNCIATOR
BACKLIGHT POS
BACKLIGHT NEG
GND
5V-SW
WHT
RED
WHT/RED
WHT/YEL
JF8
TEMP WIPER
MODE WIPER
WHT/GRN
FAN WIPER
PRE-WIRED
VIEWED FROM WIRE SIDE
232002-VUA
A/C
(IF USED)
GEN IV ECU
GEN IV WIRING DIAGRAM
REV D, 5/6/2014
TEMP
MODE
FAN
PROGRAM
* DASH LAMP
(IF USED)
*** WIDE OPEN
THROTTLE
SWITCH
(OPTIONAL)
** CIRCUIT
BREAKER
30 AMP
HEATER
CONTROL VALVE
• Dash Lamp Is Used Only With Type 232007-VUR Harness.
• Warning: Always Mount Circuit Breaker As Close to the Battery As Possible. (NOTE: Wire Between
Battery and Circuit Breaker Is Unprotected and Should Be Carefully Routed to Avoid a Short
Circuit).
17
• Wide Open Throttle Switch Contacts Close Only at Full Throttle, Which Disables A/C
Compressor.
901149 REV D 7/30/14, INST 67-72 CHEVY PICKUP wo AC EVAP KIT PG 17 OF 24
Gen IV Wiring
Connection Instruction
WIRING
HARNESS
CONTROL
WIRING
HARNESS
RED
&
WHITE
A/C
COMPRESSOR
RELAY
RED
BLUE
RED
WH
IT
E
NOTE:
MOUNT RELAY
IN DESIRED
LOCATION
UNDER DASH
Ignition Switch:
VIOLET
Violet 12V Ign Switch Source (Key On
Accessory) Position Must Be Switched.
+12V
NOTE:
WIRING YELLOW & ORANGE (IGNITION HOT
HARNESS COMING FROM
TERMINAL)
HARNESS ARE NOT
USED.
YELLOW
RUN
BAT
IGNITION
SWITCH
ORANGE
TAN
DASH BACK LIGHT+0-12v
GRAY
GRAY WIRE IS USED FOR
PROGRAMING CONTROLS
IF APPLICABLE
RED
GREEN
RED
GREEN
FIREWALL
BLACK BLUE
Heater Control Valve:
RED
LATCH
WIRING
HARNESS
WHITE
CHASSIS GROUND
NOTE: HEATER CONTROL
VALVE CONNECTION AND
CHASSIS GROUND MAY BE
LOCATED ON EITHER SIDE
OF THE FIREWALL. ENSURE
CONNECTOR IS LATCHED
FIRMLY.
HEATER
CONTROL VALVE
K
BLAC
BLUE
COMPRESSOR
WHITE
NOTE: CONNECT WHITE
WIRES DIRECTLY TO
(-) BATTERY TERMINAL
WHITE
RED
RED
CIRCUIT BREAKER
30 AMP
Install With Servo Motor Facing Down,
As Shown. Note Flow Direction Arrow
Molded Into Valve Body, And Install
Accordingly.
Binary/Trinary & Compressor:
Binary: Connect As Shown (Typical
Compressor Wiring). Be Sure
Compressor Body Is Grounded.
BINARY
SAFETY
SWITCH
BLUE
Dash Light:
Tan Wire Used Only With Vintage Air
Supplied Control Panel With LED Back
Light.
RED
WARNING:
ALWAYS MOUNT CIRCUIT BREAKER
AS CLOSE TO THE BATTERY AS POSSIBLE.
(NOTE: WIRE BETWEEN BATTERY AND
CIRCUIT BREAKER IS UNPROTECTED
AND SHOULD BE CAREFULLY ROUTED
TO AVOID A SHORT CIRCUIT).
+
-
Trinary Switch: Connect According To
Trinary Switch Wiring Diagram.
Circuit Breaker/Battery:
White Must Run To (-) Battery. Red May
Run To (+) Battery Or Starter. Mount
Circuit Breaker As Close to Battery As
Possible.
BATTERY
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18
Operation of Controls
On Gen IV systems with three lever/knob controls, the temperature control toggles between heat and A/C
operations. To activate A/C, move the temperature lever/knob all the way to cold and then back it off to the desired
vent temperature. For heat operation, move the temperature lever/knob all the way to hot and then adjust to the
desired vent temperature. The blower will momentarily change speed, each time you toggle between operations, to
indicate the change. NOTE: For proper control panel function, refer to control panel instructions for
calibration procedure.
Blower Speed
This lever/knob controls
blower speed, from
OFF to HI.
Mode Control
This lever/knob controls
the mode positions,
from DASH to FLOOR
to DEFROST, with a
blend in between.
Mode
Control
Temperature Control
This lever/knob controls
the temperature,
from HOT to COLD.
(DASH) (FLOOR)
DEF
AIR FAN
HEAT
Temperature
Control
A/C Operation
Blower Speed
Adjust to desired
speed.
Mode Control
Adjust to desired
mode position
(DASH position
recommended).
Temperature Control
For A/C operation, adjust to
coldest position to engage
compressor (Adjust between
HOT and COLD to reach
desired temperature).
DEF
AIR FAN
HEAT
Heat Operation
Blower Speed
Adjust to desired
speed.
Mode Control
Adjust to desired
mode position
(FLOOR position
recommended).
Temperature Control
For maximum heating, adjust
to hottest position (Adjust
between HOT and COLD to
reach desired temperature).
DEF
AIR FAN
HEAT
Defrost/De-fog Operation
Blower Speed
Adjust to desired
speed.
Temperature Control
Adjust to desired
temperature.
Mode Control
Adjust to DEFROST position for maximum defrost, or
between FLOOR and DEFROST positions for a bi-level
blend (Compressor is automatically engaged).
(DEFROST)
DEF
AIR FAN
HEAT
19
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Blower
Speed
901149 REV D 7/30/14, INST 67-72 CHEVY PICKUP wo AC EVAP KIT PG 20 OF 24
Symptom
Compressor will
not turn off
(All other functions
work).
3.
Compressor will
not turn on
(All other functions
work).
2.
Blower stays on
high speed when
ignition is on or off.
1b.
Blower stays on
high speed when
ignition is on.
1a.
20
System is charged.
System is not charged.
All other functions work.
No other functions work.
Condition
Check 2-pin connector at ECU housing.
Repair or replace pot/control wiring.
Replace relay.
Check for faulty A/C
potentiometer or associated
wiring.
Check for faulty A/C relay.
Check continuity to ground on white control head wire.
Check for 5V on red control head wire.
Charge system or bypass pressure switch.
Replace BSC (This will require removal of evaporator
from vehicle).
Check to ensure that no BSC wiring is damaged or
shorted to vehicle ground. The BSC operates the blower
by ground side pulse width modulation switching. The
positive wire to the blower will always be hot. If the
“ground” side of the blower is shorted to chassis ground,
the blower will run on HI.
Be sure the small, 20 GA white ground wire is connected
to the battery ground post. If it is, replace the ECU.
Verify continuity to chassis ground with white control
head wire at various points.
Verify that all pins are inserted into plug. Ensure that no
pins are bent or damaged in ECU.
Actions
Check for disconnected or
faulty thermistor.
Check for faulty A/C
potentiometer or associated
wiring (Not applicable to 3-pot
controls).
System must be charged for
compressor to engage.
Unplug 3-wire BSC control
connector from ECU. If blower
stays running, BSC is either
improperly wired or damaged.
Unplug 3-wire BSC control
connector from ECU. If blower
shuts off, ECU is either
improperly wired or damaged.
Check for damaged ground
wire (white) in control head
harness.
Check for damaged blower
switch or potentiometer and
associated wiring.
Check for damaged pins or
wires in control head plug.
Checks
Red wire at A/C pot should
have approximately 5V
with ignition on. White
wire will have continuity to
chassis ground. White/
Blue wire should vary
between 0V and 5V when
lever is moved up or down.
Disconnected or faulty
thermistor will cause
compressor to be
disabled.
To check for proper pot
function, check voltage at
white/blue wire. Voltage
should be between 0V and
5V, and will vary with pot
lever position.
Danger: Never bypass
safety switch with
engine running. Serious
injury can result.
No other part replacements
should be necessary.
See blower switch check
procedure.
Loss of ground on this wire
renders control head
inoperable.
Notes
Troubleshooting Guide
Symptom
8.
When ignition is
turned on, blower
momentarily
comes on, then
shuts off. This
occurs with the
blower switch in
the OFF position.
Erratic functions of
blower, mode,
temp, etc.
7.
Blower turns on
and off rapidly.
6.
Loss of mode door
function.
5.
System will not
turn on, or runs
intermittently.
4.
21
901149 REV D 7/30/14, INST 67-72 CHEVY PICKUP wo AC EVAP KIT PG 21 OF 24
This is an indicator that the
system has been reset. Be
sure the red power wire is on
the battery post, and not on a
switched source. Also, if the
system is pulled below 7V for
even a split second, the
system will reset.
Run red power wire directly to battery.
Repair or replace.
Charge battery.
Check for faulty battery or
alternator.
Battery voltage is less
than 12V.
Check for damaged switch or
pot and associated wiring.
Ensure all system grounds and power connections are
clean and tight.
Verify proper meter function by checking the condition of
a known good battery.
Check for positive power at heater valve green wire and
blower red wire. Check for ground on control head white
wire.
Install capacitors on ignition coil and alternator. Ensure
good ground at all points. Relocate coil and associated
wiring away from ECU and ECU wiring. Check for burned
or loose plug wires.
Actions
Check for at least 12V at
circuit breaker.
Check for damaged stepper
motor or wiring.
Check for obstructed or
binding mode doors.
Check for damaged mode
switch or potentiometer and
associated wiring.
Verify battery voltage is
greater than 10 volts and less
than 16.
Verify connections on power
lead, ignition lead, and both
white ground wires.
Noise interference from either
ignition or alternator.
Checks
Battery voltage is at least
12V.
Partial function of mode
doors.
No mode change at all.
Will not turn on under
any conditions.
Works when engine is not
running; shuts off when
engine is started
(Typically early Gen IV,
but possible on all
versions).
Condition
System shuts off blower at
10V. Poor connections or
weak battery can cause
shutdown at up to 11V.
Typically caused by
evaporator housing
installed in a bind in the
vehicle. Be sure all
mounting locations line up
and don’t have to be forced
into position.
Ignition noise (radiated or
conducted) will cause the
system to shut down due to
high voltage spikes. If this
is suspected, check with a
quality oscilloscope. Spikes
greater than 16V will shut
down the ECU. Install a
radio capacitor at the
positive post of the ignition
coil (See radio capacitor
installation bulletin). A
faulty alternator or worn
out battery can also result
in this condition.
Notes
Troubleshooting Guide (Cont.)
Driver/Passenger Side
Louver Template
TEMPLATE FOR DRIVER SIDE
END OF DASH
DRIVER SIDE
CUT
2 ½”
DIAMETER
HOLE
BOTTOM EDGE
OF DASH FACE
TEMPLATE FOR PASSENGER SIDE
END OF DASH
PASSENGER SIDE
CUT
2 ½”
DIAMETER
HOLE
BOTTOM EDGE
OF DASH FACE
901149 REV D 7/30/14, INST 67-72 CHEVY PICKUP wo AC EVAP KIT PG 22 OF 24
22
Center Louver Dimensions
5 ½”
1 �¼”
Center Louver Dimensions
1 1/16”
Top of Radio Opening
23
901149 REV D 7/30/14, INST 67-72 CHEVY PICKUP wo AC EVAP KIT PG 23 OF 24
Packing List
Evaporator Kit (751170)
No.
1.
2.
Qty.
1
1
Part No.
Description
744005
791170
Gen IV 3-Vent Evaporator Sub Case w/ 204 ECU
Accessory Kit 67-72 Chevy Pickup without A/C
Checked By:
Packed By:
Date:
1
Gen IV 3-Vent
Evaporator Sub Case
w/ 204 ECU
744005
2
Accessory Kit
791170
NOTE: Images may not depict actual parts and quantities.
Refer to packing list for actual parts and quantities.
901149 REV D 7/30/14, INST 67-72 CHEVY PICKUP wo AC EVAP KIT PG 24 OF 24