HVAC Mode Control Switch (Heat a/c Vent)

This category on the website [ Switches and Wiring ] we are giving you all of the information related to the individual switches in the Buick Turbo Regal, along with the associated wiring, connector plugs, etc.

VEHICLE APPLICATION:

Buick Regal, T-Type, Turbo T, Limited, Grand National, GNX

SWITCH NAME:

HVAC Mode Control Switch
HVAC rotary mode control switch

PURPOSE OF SWITCH:

controls the mode of the a/c system (C60 manual; and heat vent defrost options)

TURNS ON-OFF / FUNCTIONS / USED WHEN:

when you move the mode lever, it turns on the various systems

LOCATION IN VEHICLE:

interior, center of car, on dash, above radio

ORIGINAL GM PART NUMBER:

SWITCH / BASE COLOR:

black brass tabs

CONNECTOR PLUG COLOR (SWITCH SIDE):

n/a

WIRES ATTACHED (SWITCH SIDE):

n/a

CONNECTOR PLUG COLOR (HARNESS SIDE):

black

NUMBER OF WIRES ATTACHED (HARNESS SIDE):

COLOR & PURPOSE OF (HARNESS SIDE) WIRES:

AIR CONDITIONING:
(with C60 manual A/C)

MODE CONTROL:

brown “E”, goes to (junction) to a/c fuse
(connects with trunk release)

light green “C”, goes to (junction) to pressure cycling switch “B”

[2 wires on 1 terminal]
brown-white “B”, goes to heater a/c control head “D” (blower switch)
brown-white “B”, goes to blower resistor “A”

…

OTHER CONNECTED WIRES ON HVAC UNIT (not on all models):

brown “B” [voltage regulator], goes to (junction) to a/c fuse

orange “B” (memory power), goes to (several junctions) to cig-clk fuse
(connects with power antenna)

gray “D” (display dim input), goes to instrument cluster lights

black “D” (lights ground) and “E” (unit ground), goes to (junction) to ground

pink-black “H” (blower control), goes to a/c air delivery & temp control

light green-black “B” (blower control), goes to a/c blower controls (HVAC fan speed) [“D” on blower and a/c clutch control module]

light green-black “E” (temp input), goes to a/c air delivery & temp control

black “A” (blower control), goes to a/c air delivery & temp control

brown-white “A” (compressor power reset), goes to (junction) to blower & a/c clutch control module “C” (power reset)

purple “C” (compressor control), goes to (junction) to blower & a/c clutch control module “A” (compressor control signal)
[6 volts = on; 12 volts = off]

PHOTOS OF SWITCH AND CONNECTED WIRES:
.

OTHER NOTES:

labelled “heater a/c control head” on diagrams.

There are a lot of wires within the a/c unit (control head).
Some control the function (heat, a/c, etc), some control the blower speed.
Some control the function (normal, max) within the function (a/c).
Others are for the light, power/ground, etc.,

[SEE HVAC Fan Speed Control Switch]

[SEE HVAC light bulb]

Most Turbo Buicks DO have air conditioning as an option in their Gbody Regals, but we figured we would include these photos of a “non-a/c” control head, as well as what the blower harness looks like (it’s different than the cars that have a/c), in case someone can use this info.
.