Pontiac TRANS AM 1977 Service Manual page 75

18-24 1977 PONTIAC SERVICE MANUAL
1. No blower, any speed
a. 1 to G
compressor clutch
engages
b. 2 to G
3 volts or more
Under 3 volts
3 volts or more
Under 3 volts
Faulty motor, ground
or capacitor lead.
Go to b.
Faulty relay, or purple
wire, relay to motor.
Stalled motor.
2. No blower and
If Heater-A/C fuse is
compressor clutch
blown, check for a ground
does not engage
in circuit, or excessive
motor or clutch current.
If not, check for an open
lead from ignition switch
to low blower delay (in-
car ambient) switch or
bad A/C harness ground.
3. No low speed 3 to G 10 volts or more Faulty resistor.
Under 10 volts Faulty low blower delay
(in-car ambient) switch
or wire to resistor.
4. No low or MI Speed
Faulty resistor.
5. No blower except
2 to G
in high or max A/C
3 volts or more Faulty relay.
Under 3 volts
Faulty resistor or wire
from resistor to relay.
6. No high blower 9 to G
under any condition
Place blower switch
in HIGH
10 volts or more
Faulty high blower relay,
open red wire to relay,
or bad relay ground.
Under 10 volts
Faulty wire to relay coil
from blower switch.
7. No high speed except
Faulty blower switch.
in
rnax
A/C
8. No high speed in
Faulty A/C control or
Max A/C
wire from A/C control to
blower switch.
9. No M 1 speed
Faulty blower switch or
wire to resistor.
10. No M2 speed
Faulty blower switch or
wire to resistor.
11. No M1, M2 or high Voltage at
with switch (OK in
A/C control
max A/C). Place terminal #2
blower switch in
HIGH
10 volts or more
Faulty blower switch to
wire to blower switch.
Under 10 volts
Faulty A/C control.