K Yukon/Denali 4WD V8-5.7L VIN R (2000)
Control Assembly: Description and Operation
Control Assembly, HVAC
The air conditioning system on C/K models is electronically controlled. Three backlit, rotary knobs provide full control of the system. The rotary knobs
control the following items:
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The blower speed
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The air temperature
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The mode of operation
Two push-to-latch buttons select recirculation mode for maximum cooling and control over the air conditioning compressor.
The blower speed rotary control has 4 fan speeds and an OFF position. When the blower fan is turned off, all the HVAC operations turn off also.
The temperature rotary control has 180 degrees of travel. A detent at the full cold-end of travel engages recirculation. Operating the system with the
temperature control placed in the detent results in maximum cooling. Air inside the passenger compartment recirculates through the blower case. Use of
outside air is minimal. Manually select recirculation by pushing the RECIRC button.
The mode rotary control has 3 major detents that indicate mode positions:
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The vent
-
The floor
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The defrost
Placing the control anywhere in between the major detents results in air output blending between the two modes. The recirculation mode is not available
anytime DEFROST is selected, or while air is being blended out of the defrost outlets.
Automatic recirculation occurs when the compressor head pressures exceed 2275 kPa (350 psi) and disables after the head pressures reach 1724 kPa
(250 psi). When activated, automatic recirculation cannot be manually disabled by the MAX button.
