GMC chervolet camaro 1999 Service Manual page 226

\
I
\
,I
HVAC
Service Caps Seal
The primary seal for the service ports is the sealing
cap. The cap contains a specially designed 0-ring or
gasket which provides a leak free seal. Should the
cap be loose, missing, or the wrong usage, a loss of
refrigerant could result.
HVAC Blower Controls Circuit Description
LO-M2 Positions
When the ignition switch is in the RUN position
voltage is applied through the HVAC Fuse 6,
circuit 241, to the HVAC control selector switch.
When the selector switch is switched to any position,
except OFF, voltage is supplied to the blower
switch through circuit 66.
When the blower switch is in the LO position voltage
is applied to the blower switch, to the blower
resistor through circuit 60, to the blower motor relay
through circuit 101 and then to the blower motor
through circuit 65. The blower motor receives ground
at all times through G201, circuit 850. When voltage
is applied to the blower motor, the motor runs
at low speed.
When the blower switch is switched to M 1 or M2, the
blower control system works as described above
except for the speed of the blower motor. The blower
motor has several resistors that voltage flows
through to get to the blower motor depending which
position the blower switch is in. In the LO position,
voltage passes through 4 resistors. In the M1 position,
voltage passes 3 resistors and in the M2 position
voltage passes through 2 resistors. As the resistance
is decreased the blower runs at a faster speed.
HVAC System - Manual 1-135
HI Position
The HI position in the blower switch works differently
than the LO-M2 positions. When the ignition switch
is in the RUN position voltage is applied through the
HV AC Fuse 6, circuit 241, to the HVAC control
selector switch. When the selector switch is switched
to any position, except OFF, voltage is supplied to
the blower switch through circuit 66.
When the blower switch is moved to the HI position
voltage is applied through the HVAC control selector
switch to the blower motor relay through circuit 52. The
blower motor relay receives ground through G200,
circuit 650 at all times. When voltage is applied
through circuit 52 the solenoid within the blower motor
is energized closing the internal switch within the
blower motor relay. Voltage is always applied to the
relay through the IP 1 MaxiFuse, circuit 1202.
When the internal switch is closed voltage is applied
to the blower motor through circuit 1202, blower motor
relay, and circuit 65. This causes the motor to run
at its fastest speed due to that the voltage does not
have to travel through a resistor. The blower motor
receives ground at all times through G201, circuit 850.