On-Bench Procedure-Programmer - Pontiac FIREBIRD 1972 Service Manual

1B-8 1972 PONTIAC SERVICE MANUAL
voltmeter will read battery voltage. The Lo Relay is
operated by:
a. Hot engine thermal switch.
b. Hot in-car temperature switch.
c. Control head in VENT or DEFROST position.
If the relay does not energize in VENT or DE-
FROST, the relay or the control head printed circuit
switch is defective.
Auto Relay Test
18. Place the tester Temperature Dial Calibration switch
in the OFF position and the Voltmeter knob in the
"AUTO RELAY" position.
19. Place the control selector lever in the DEFROST
position. If full battery voltage is not obtained, there
is a defect in the auto relay circuit. The Auto Relay
is operated by:
a. Hot engine thermal switch.
b. Hot in-car temperature switch.
c. Control head in DEFROST.
If the relay does not energize in control head DE-
FROST position, the relay or the control head
printed circuit switch is defective.
Programmer Blower Switch Test
Place ATC Tester Temperature Dial Calibration
switch in the OFF position, the Voltage knob in the
"BLOWER" position, and the Manual- Automatic
switch in the MANUAL position.
Using the MANUAL CONTROL, move the pro-
grammer from full heat to the full A/C position. The
voltage at the blower (coming from programmer ter-
minal #6) should be battery voltage in full heat. As
the programmer moves from full heat, the voltage
should drop in steps, indicating different blower
speeds, and then increase in steps to battery voltage
in full A/C. If the voltage steps are not present or
battery voltage is not indicated on the tester voltme-
ter when in full heat and full A/C operation, the
programmer is defective. Remove and troubleshoot
the programmer (See ON BENCH PROCEDURE-
PROGRAMMER).
ON BENCH PROCEDURE-PROGRAMMER
Before attempting to repair or adjust the programmer,
locate the output shaft, the feedback potentiometer, the
vacuum motor, the blower switch, the vacuum checking
relay, the transducer and the rotary vacuum valve. Refer
to Fig. 1B-6 for identification of all programmer compo-
nents.
Equipment required:
D.C. power supply rated at 5 amperes at 12 volts.
J 23678 Automatic Temperature Control Tester.
Vacuum supply capable of 20 inches of Hg, or more.
1/4" hollow socket and drive.
Medium size blade screwdriver.
Long-nose pliers.
J 23713 electrical test connector.
When following the troubleshooting procedure, do not
skip any steps unless instructed to do so. The ATC Tester
Manual-Automatic switch should always be in the
MANUAL position and the Temperature Dial Calibra-
tion switch should always be in the OFF position when
troubleshooting the programmer on the bench.
Plug male connector of ATC Tester electrical harness
into programmer.
Plug J 237 13 electrical test connector into female
connector of ATC Tester electrical harness.
Plug dummy plug from tester onto the programmer
rotary valve and connect it to the vacuum supply.
Turn on the vacuum supply to 20 inches Hg. or more.
Connect positive lead of 12 volt DC power supply to
yellow wire from electrical test connector. Connect
negative lead of power supply to black wire of test
connector. Voltmeter on tester should read 12 volts
when in "#2 Feed" position, "#7 Lo-Relay" posi-
tion and "#8 Auto Relay" position. If it does not,
check the voltage supply and hook-up.
On the ATC Tester, place the Manual-Automatic
switch in the MANUAL position and the Tempera-
ture Dial Calibration switch in the OFF position.
Rotate the ATC Tester Manual Control knob from
MAX. HEAT to MAX. COLD. (Make sure the
power supply is adjusted for 12 volts DC and vacuum
supply is at 20 inches Hg. or more.) The programmer
output shaft should rotate 120 degrees (1/3 rotation
of shaft) from maximum heat to maximum cold. If it
does rotate normally, skip to Step 18.
If the programmer output shaft does not operate
properly in Step 6, remove the cover of the program-
mer and reconnect the tester electrical connector and
the rotary vacuum valve dummy plug. Recheck pro-
grammer operation as described in Step 6. If the pro-