AIR CONDITIONING – GMC Sierra 2500 1999 – SYSTEM WIRING DIAGRAMS

AIR CONDITIONING

4.3L

4.3L VIN W, Compressor Wiring Diagram for GMC Sierra 2500 1999

List of elements for 4.3L VIN W, Compressor Wiring Diagram for GMC Sierra 2500 1999:

• 4.3l
• A/c automatic recirculating switch (in a/c muffler hose)
• A/c comp fuse 10a
• A/c compressor clutch
• A/c compressor clutch relay
• A/c high pressure cutout switch (on a/c compressor)
• A/c low pressure cutout switch (right side of accumulator)
• A/c request
• All other gas
• Diesel
• G100 (on left radiator support bracket)
• G102 (front of engine block)
• Hot at all times
• Hot in run or start
• Hvac control module
• Ign e fuse 10a
• Relay cont
• S101 (engine harn)
• S102 (engine harn)
• Switch input
• Underhood bussed electrical center
• Vehicle control module (left side of engine compt)

4.3L VIN W, Heater Wiring Diagram for GMC Sierra 2500 1999

List of elements for 4.3L VIN W, Heater Wiring Diagram for GMC Sierra 2500 1999:

• Blower motor
• Blower motor relay
• Blower motor resistor/ relay assembly (on hvac module, near blower motor)
• Blower motor switch
• D12
• Frt hvac fuse 30a
• G200 (right side of dash, at "a" pillar)
• Hot at all times
• Hot in run
• Htr-a/c fuse 25a
• Interior lights system
• Left bussed electrical center
• Off
• Tan
• Underhood bussed electrical center

4.3L VIN W, Manual A/C Wiring Diagram, Base for GMC Sierra 2500 1999

List of elements for 4.3L VIN W, Manual A/C Wiring Diagram, Base for GMC Sierra 2500 1999:

• 4.3l 4.3l
• A a/c disable
• A/c automatic recirculating switch (in a/c muffler hose)
• A/c comp fuse 10a
• A/c compressor clutch
• A/c compressor clutch relay
• A/c high pressure cutout switch (on a/c compressor)
• A/c low pressure cutout switch (on a/c compressor)
• A/c request
• All other gas all other gas
• B mode signal
• Blower motor (under right side of dash)
• Blower motor resistor/relay assembly (on hvac module, near blower motor)
• C 1995 vftc
• C ground
• C1 c1
• C2 c2
• C3 c3
• D recirc signal
• D12
• Diesel diesel
• E illumination
• F temp signal
• Frt hvac fuse 30a
• G feedback
• G100 (on left radiator support bracket)
• G102 (front of engine block)
• G200 (right side of dash, at "a" pillar)
• G203 (on upper left dash at "a" pillar)
• H 5v reference
• High
• Hot at all times
• Hot in run
• Hot in run and start
• Htr-a/c fuse 25a
• Hvac 1 fuse 10a
• Hvac control module (under radio)
• Ign e fuse 10a
• Interior lights system
• J rear defog
• K ign power
• L a/c request
• Left bussed electrical center
• Low
• M feedback
• Mid bussed electrical center
• Mode door motor (left side of hvac module)
• Off
• Rear defogger system
• Recirculation door motor (top of hvac module)
• Red
• Relay cont
• S101 (engine harn)
• S102 (engine harn)
• Switch sig
• Tan
• Temperature door motor (bottom center of hvac module)
• Underhood bussed electrical center
• Vehicle vehicle control control module module (left side (left side of engine of engine compt) compt)

4.3L VIN W, Manual A/C Wiring Diagram, Up Level for GMC Sierra 2500 1999

List of elements for 4.3L VIN W, Manual A/C Wiring Diagram, Up Level for GMC Sierra 2500 1999:

• 4.3l 4.3l
• A a/c disable
• A/c automatic recirculating switch (in a/c muffler hose)
• A/c comp fuse 10a
• A/c compressor clutch
• A/c compressor clutch relay
• A/c high pressure cutout switch (on a/c compressor)
• A/c low pressure cutout switch (on right side of accumulator)
• A/c request
• All other gas all other gas
• B mode signal
• Blower motor (under right side of dash)
• Blower motor resistor/relay assembly (on hvac module, near blower motor)
• C 1995 vftc
• C ground
• C1 c1
• C2 c2
• C3 c3
• D recirc signal
• D12
• Diesel diesel
• E illumination
• F temp signal
• Frt hvac fuse 30a
• G feedback
• G100 (on left radiator support bracket)
• G102 (front of engine block)
• G200 (on upper dash, near "a" pillar)
• H 5v reference
• Hot at all times
• Hot in run
• Hot in run and start
• Htr-a/c fuse 25a
• Hvac 1 fuse 10a
• Hvac control module (under radio)
• Ign e fuse 10a
• Interior lights system
• J rear defog
• K ign power
• L a/c request
• Left bussed electrical center
• M feedback
• Mode door motor (left side of hvac module)
• Module)
• Off
• Rear defogger system
• Recirculation door motor (top of hvac module)
• Red
• Relay cont
• Right bussed electrical center
• S101 (engine harn)
• S102 (engine harn)
• Switch sig
• Tan
• Temperature door motor (near bottom of hvac
• Underhood bussed electrical center
• Vehicle vehicle control control module module (left side (left side of engine of engine compt) compt)

4.8L

4.8L VIN V, Compressor Wiring Diagram for GMC Sierra 2500 1999

List of elements for 4.8L VIN V, Compressor Wiring Diagram for GMC Sierra 2500 1999:

• 4.3l
• A/c automatic recirculating switch (in a/c muffler hose)
• A/c comp fuse 10a
• A/c compressor clutch
• A/c compressor clutch relay
• A/c high pressure cutout switch (on a/c compressor)
• A/c low pressure cutout switch (right side of accumulator)
• A/c request
• All other gas
• Diesel
• G100 (on left radiator support bracket)
• G102 (front of engine block)
• Hot at all times
• Hot in run or start
• Hvac control module
• Ign e fuse 10a
• Relay cont
• S101 (engine harn)
• S102 (engine harn)
• Switch input
• Underhood bussed electrical center
• Vehicle control module (left side of engine compt)

4.8L VIN V, Heater Wiring Diagram for GMC Sierra 2500 1999

List of elements for 4.8L VIN V, Heater Wiring Diagram for GMC Sierra 2500 1999:

• Blower motor
• Blower motor relay
• Blower motor resistor/ relay assembly (on hvac module, near blower motor)
• Blower motor switch
• D12
• Frt hvac fuse 30a
• G200 (right side of dash, at "a" pillar)
• Hot at all times
• Hot in run
• Htr-a/c fuse 25a
• Interior lights system
• Left bussed electrical center
• Off
• Tan
• Underhood bussed electrical center

4.8L VIN V, Manual A/C Wiring Diagram, Base for GMC Sierra 2500 1999

List of elements for 4.8L VIN V, Manual A/C Wiring Diagram, Base for GMC Sierra 2500 1999:

• 4.3l 4.3l
• A a/c disable
• A/c automatic recirculating switch (in a/c muffler hose)
• A/c comp fuse 10a
• A/c compressor clutch
• A/c compressor clutch relay
• A/c high pressure cutout switch (on a/c compressor)
• A/c low pressure cutout switch (on a/c compressor)
• A/c request
• All other gas all other gas
• B mode signal
• Blower motor (under right side of dash)
• Blower motor resistor/relay assembly (on hvac module, near blower motor)
• C 1995 vftc
• C ground
• C1 c1
• C2 c2
• C3 c3
• D recirc signal
• D12
• Diesel diesel
• E illumination
• F temp signal
• Frt hvac fuse 30a
• G feedback
• G100 (on left radiator support bracket)
• G102 (front of engine block)
• G200 (right side of dash, at "a" pillar)
• G203 (on upper left dash at "a" pillar)
• H 5v reference
• High
• Hot at all times
• Hot in run
• Hot in run and start
• Htr-a/c fuse 25a
• Hvac 1 fuse 10a
• Hvac control module (under radio)
• Ign e fuse 10a
• Interior lights system
• J rear defog
• K ign power
• L a/c request
• Left bussed electrical center
• Low
• M feedback
• Mid bussed electrical center
• Mode door motor (left side of hvac module)
• Off
• Rear defogger system
• Recirculation door motor (top of hvac module)
• Red
• Relay cont
• S101 (engine harn)
• S102 (engine harn)
• Switch sig
• Tan
• Temperature door motor (bottom center of hvac module)
• Underhood bussed electrical center
• Vehicle vehicle control control module module (left side (left side of engine of engine compt) compt)

4.8L VIN V, Manual A/C Wiring Diagram, Up Level for GMC Sierra 2500 1999

List of elements for 4.8L VIN V, Manual A/C Wiring Diagram, Up Level for GMC Sierra 2500 1999:

• 4.3l 4.3l
• A a/c disable
• A/c automatic recirculating switch (in a/c muffler hose)
• A/c comp fuse 10a
• A/c compressor clutch
• A/c compressor clutch relay
• A/c high pressure cutout switch (on a/c compressor)
• A/c low pressure cutout switch (on right side of accumulator)
• A/c request
• All other gas all other gas
• B mode signal
• Blower motor (under right side of dash)
• Blower motor resistor/relay assembly (on hvac module, near blower motor)
• C 1995 vftc
• C ground
• C1 c1
• C2 c2
• C3 c3
• D recirc signal
• D12
• Diesel diesel
• E illumination
• F temp signal
• Frt hvac fuse 30a
• G feedback
• G100 (on left radiator support bracket)
• G102 (front of engine block)
• G200 (on upper dash, near "a" pillar)
• H 5v reference
• Hot at all times
• Hot in run
• Hot in run and start
• Htr-a/c fuse 25a
• Hvac 1 fuse 10a
• Hvac control module (under radio)
• Ign e fuse 10a
• Interior lights system
• J rear defog
• K ign power
• L a/c request
• Left bussed electrical center
• M feedback
• Mode door motor (left side of hvac module)
• Module)
• Off
• Rear defogger system
• Recirculation door motor (top of hvac module)
• Red
• Relay cont
• Right bussed electrical center
• S101 (engine harn)
• S102 (engine harn)
• Switch sig
• Tan
• Temperature door motor (near bottom of hvac
• Underhood bussed electrical center
• Vehicle vehicle control control module module (left side (left side of engine of engine compt) compt)

5.3L

5.3L VIN T, Compressor Wiring Diagram for GMC Sierra 2500 1999

List of elements for 5.3L VIN T, Compressor Wiring Diagram for GMC Sierra 2500 1999:

• 4.3l
• A/c automatic recirculating switch (in a/c muffler hose)
• A/c comp fuse 10a
• A/c compressor clutch
• A/c compressor clutch relay
• A/c high pressure cutout switch (on a/c compressor)
• A/c low pressure cutout switch (right side of accumulator)
• A/c request
• All other gas
• Diesel
• G100 (on left radiator support bracket)
• G102 (front of engine block)
• Hot at all times
• Hot in run or start
• Hvac control module
• Ign e fuse 10a
• Relay cont
• S101 (engine harn)
• S102 (engine harn)
• Switch input
• Underhood bussed electrical center
• Vehicle control module (left side of engine compt)

5.3L VIN T, Heater Wiring Diagram for GMC Sierra 2500 1999

List of elements for 5.3L VIN T, Heater Wiring Diagram for GMC Sierra 2500 1999:

• Blower motor
• Blower motor relay
• Blower motor resistor/ relay assembly (on hvac module, near blower motor)
• Blower motor switch
• D12
• Frt hvac fuse 30a
• G200 (right side of dash, at "a" pillar)
• Hot at all times
• Hot in run
• Htr-a/c fuse 25a
• Interior lights system
• Left bussed electrical center
• Off
• Tan
• Underhood bussed electrical center

5.3L VIN T, Manual A/C Wiring Diagram, Base for GMC Sierra 2500 1999

List of elements for 5.3L VIN T, Manual A/C Wiring Diagram, Base for GMC Sierra 2500 1999:

• 4.3l 4.3l
• A a/c disable
• A/c automatic recirculating switch (in a/c muffler hose)
• A/c comp fuse 10a
• A/c compressor clutch
• A/c compressor clutch relay
• A/c high pressure cutout switch (on a/c compressor)
• A/c low pressure cutout switch (on a/c compressor)
• A/c request
• All other gas all other gas
• B mode signal
• Blower motor (under right side of dash)
• Blower motor resistor/relay assembly (on hvac module, near blower motor)
• C 1995 vftc
• C ground
• C1 c1
• C2 c2
• C3 c3
• D recirc signal
• D12
• Diesel diesel
• E illumination
• F temp signal
• Frt hvac fuse 30a
• G feedback
• G100 (on left radiator support bracket)
• G102 (front of engine block)
• G200 (right side of dash, at "a" pillar)
• G203 (on upper left dash at "a" pillar)
• H 5v reference
• High
• Hot at all times
• Hot in run
• Hot in run and start
• Htr-a/c fuse 25a
• Hvac 1 fuse 10a
• Hvac control module (under radio)
• Ign e fuse 10a
• Interior lights system
• J rear defog
• K ign power
• L a/c request
• Left bussed electrical center
• Low
• M feedback
• Mid bussed electrical center
• Mode door motor (left side of hvac module)
• Off
• Rear defogger system
• Recirculation door motor (top of hvac module)
• Red
• Relay cont
• S101 (engine harn)
• S102 (engine harn)
• Switch sig
• Tan
• Temperature door motor (bottom center of hvac module)
• Underhood bussed electrical center
• Vehicle vehicle control control module module (left side (left side of engine of engine compt) compt)

5.3L VIN T, Manual A/C Wiring Diagram, Up Level for GMC Sierra 2500 1999

List of elements for 5.3L VIN T, Manual A/C Wiring Diagram, Up Level for GMC Sierra 2500 1999:

• 4.3l 4.3l
• A a/c disable
• A/c automatic recirculating switch (in a/c muffler hose)
• A/c comp fuse 10a
• A/c compressor clutch
• A/c compressor clutch relay
• A/c high pressure cutout switch (on a/c compressor)
• A/c low pressure cutout switch (on right side of accumulator)
• A/c request
• All other gas all other gas
• B mode signal
• Blower motor (under right side of dash)
• Blower motor resistor/relay assembly (on hvac module, near blower motor)
• C 1995 vftc
• C ground
• C1 c1
• C2 c2
• C3 c3
• D recirc signal
• D12
• Diesel diesel
• E illumination
• F temp signal
• Frt hvac fuse 30a
• G feedback
• G100 (on left radiator support bracket)
• G102 (front of engine block)
• G200 (on upper dash, near "a" pillar)
• H 5v reference
• Hot at all times
• Hot in run
• Hot in run and start
• Htr-a/c fuse 25a
• Hvac 1 fuse 10a
• Hvac control module (under radio)
• Ign e fuse 10a
• Interior lights system
• J rear defog
• K ign power
• L a/c request
• Left bussed electrical center
• M feedback
• Mode door motor (left side of hvac module)
• Module)
• Off
• Rear defogger system
• Recirculation door motor (top of hvac module)
• Red
• Relay cont
• Right bussed electrical center
• S101 (engine harn)
• S102 (engine harn)
• Switch sig
• Tan
• Temperature door motor (near bottom of hvac
• Underhood bussed electrical center
• Vehicle vehicle control control module module (left side (left side of engine of engine compt) compt)