Tundra 4WD V8-4.7L (2UZ-FE) (2003)
a. Check the continuity exists between terminals 1 and 3 of blower switch connector, when turn the mode selector to DEF. position and F/DEF.
position.
If no continuity exists, proceed to next step.
b. Check the continuity exists between terminals of A/C mode switch.
If no continuity exists, replace the A/C mode switch.
If continuity exists, check or replace heater control housing base.