I have 1996 5.7L Suburban auto 4x4 that I just picked up. The A/C blows cold at all levels. The problem is the ticking noise. Whenever I have the fan on, for A/C or heat, there is a clicking noise that comes from under the dash somewhere. It is directly related to the fan speed. No clicking when the fan is off and the clicking increases as the fan increases in speed. I searched the forums already, but can't quite find my exact problem. Any ideas?

 

Welcome to the forum.

Could be something as simple as a tree leaf caught in the fan blades.

 

Remove your blower motor and the problem should become obvious. You can test the motor when it is out by hooking the wires to it in the same locations they were. I would guess the noise is gone. If the noise is not gone, you may need a new blower motor. Otherwise suspect debris hitting your blades as has been suggested.