Pontiac FIREBIRD 1972 Service Manual page 191

1 B-4
1972 PONTIAC SERVICE MANUAL
Remove the cover of the programmer (while it is still
mounted in the car) and connect the J 23678 ATC
Tester electrical harness to the programmer and the
car ATC harness.
Place the control head selector lever in the AUTO
position and the temperature dial at 75".
On the tester, place the Temperature Dial Calibra-
tion switch in the OFF position and the Manual-
Automatic switch in the MANUAL position.
Rotate the Manual Control knob to MAX. HEAT.
The programmer should move to the full heat posi-
tion and the fan should run at high blower speed.
(The vacuum motor mechanism will move into the
vacuum motor.) Rotate the knob to MAX. COLD.
The programmer should move to the full A/C posi-
tion and the fan should run at high blower speed.
(The vacuum motor mechanism will move out of the
vacuum motor.) If only partial programmer move-
ment occurs or "Hi blower" is not obtained at both
extremes, make the air mix (temperature) door link
adjustment before proceding to the next step. If the
programmer does not move at all, skip to Step 9.
Rotate the Manual Control knob slowly counter-
clockwise. The vacuum motor mechanism should
first start to move at precisely 180 ohms ( + 1 ohm)
on the Manual Control knob. If this first movement
occurs before or after 180 ohms, make the Program-
mer Amplifier Calibration (Feedback "Pot" Adjust-
ment) described under ON BENCH
PROCEDURE-PROGRAMMER.
Rotating the Manual Control knob to the MAX.
COLD position should cause the system to shift to
full A/C operation and the vacuum motor mech-
anism will move out of the vacuum motor. If the
programmer moves normally when rotating the
Manual Control knob, skip to Step 11.
PROGRAMMER DOES NOT MOVE.
9. On the ATC Tester, place the Temperature Dial Cali-
bration switch in the OFF position and the VOLTM-
ETER control in the "PROGRAMMER 12-V
SUPPLY" position. Battery voltage should appear
on meter. No voltage indicates the lack of a ground
on terminal # 1 of the programmer or the lack of
battery supply to terminal #2 of the programmer.
a. If battery voltage appears on voltmeter, proceed
to step 10.
b. If no voltage appears on voltmeter, place voltme-
ter knob in the "Probe and Clip" position. Deter-
mine if programmer terminal
#
1 is ungrounded
and/or terminal #2 has no battery voltage ap-
plied to it. Trace appropriate wire@) to find mal-
function in car ATC electrical system (See Fig.
1 B-2).
10. Plug the tester dummy vacuum plug on the program-
mer vacuum valve. Connect the dummy plug hose to
the vacuum supply hose (Port #2) in the car vacuum
harness. Make sure vacuum is present. The program-
mer now has vacuum supply with no car vacuum
system components connected. If the programmer
functions using the MANUAL CONTROL on the
tester, troubleshoot the ATC vacuum system (See
Figs. 1 B-3, 1 B-4 and
1
B-5). If the programmer does
not function, the defect is in the programmer.
Remove the dummy plug and reconnect the vacuum
harness after making this test. If defect is in program-
mer, remove the programmer and follow procedure
under ON BENCH PROCEDURE-PROGRAM-
MER.
Sensor String Test
NOTE: Do notperfom sensor string test on car
which has been run at idle for a long penbd of
time in a heated building. This condition pro-
duces sumcient engine heat to heat the ambient
sensor and cause lower resistance readings than
specifid in foflo wing procedure even though
no problem exists in the sensor stnng.
Place the control head selector lever in the AUTO
position and the temperature dial on 75".
On the J 23678 ATC Tester, place the Manual-
Automatic switch in the AUTOMATIC position.
Observe position of vacuum motor mechanism.
On the ATC Tester, switch the Manual-Automatic
switch to the MANUAL position and adjust the
Manual Control knob until the vacuum motor mech-
anism assumes the same position it had in Step 13.
When the Manual Control knob is properly' adjusted,
switching the Manual-Automatic switch back and
forth will result in no movement of the vacuum mo-
tor mechanism.
Read the setting of the MANUAL CONTROL. This
resistance reading is the same as the resistance of the
two sensors and the temperature dial combined and
should be 120 to 150 ohms at 70" to 75" F. room
temperature. If this reading is incorrect, try calibrat-
ing the temperature dial (See TEMPERATURE
DIAL CALIBRATION
-
B SERIES). If the calibra-
tion can be accomplished, the temperature dial is
"good". Visually check the ambient and in-car sen-
sors for shorts or bad connections.
Relay Test
Place the tester Temperature Dial Calibration switch
in the OFF position and the Voltmeter knob in the
"LO RELAY" position.
Place the control head selector lever in VENT or
DEFROST position. If the Lo Relay is energized, the