Functional Check: Notes

WARNING: This page is about a different car, the 1999 GMC Sierra and 1999 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

As an aid in determining whether or not the following are operating properly, refer to the System Performance table:

The air conditioning (A/C)
Electrical
Air
The refrigeration systems

The operation of the air conditioning (A/C) blower at all 5 speeds, in any position except the OFF position, and the engagement of the compressor clutch indicate that the electrical circuits are functioning properly.
The operation of the A/C control selector and the distribution of air from the designated outlets indicates proper functioning.

Fig 1: HVAC Position ICONS

Courtesy of GENERAL MOTORS CORP.

Callout	Component Name
1	Upper Mode
2	Bi-Level Mode
3	Lower Mode
4	Defog Mode
5	Defrost Mode

System Performance

Control Settings			System Response
Mode Control	Temp Control	Fan Switch	Blower Speed	Heater Outlets	A/C Outlets	Defroster Outlets	See Remarks
-	Cold	-	Off	No Air Flow	No Air Flow	No Air Flow	-
Upper	Cold	Lo	Low	No Air Flow	Air Flow	No Air Flow	A,C,D
Upper	Cold	Low to Hi	Low to High	No Air Flow	Air Flow	No Air Flow	A,B,C,D
Upper	Cold	Hi	High	No Air Flow	Air Flow	No Air Flow	A,D
Bi-Level	Cold	Hi	High	Air Flow	Air Flow	No Air Flow	A,D
Lower	Hot	Hi	High	Air Flow	No Air Flow	Min Air Flow	A,D
Defog	Hot	Hi	High	Air Flow	No Air Flow	Air Flow	A,D
Defrost	Hot	Hi	High	Min Air Flow	No Air Flow	Air Flow	A,D
A = Engagement of the detent must be felt in each mode. B = Noticeable blower speed increase must occur from low to Med 1, Med 2, Med 3, and high. C = Listen for changes of air noise from recirculation door closing. D = Some air bleed will occur through defroster and side window defogger vents in heater mode.