clicking/knocking noise

[harryd14]

the past few days i have noticed a clicking/knocking noise coming from the engine bay, right near the back almost like its coming from the floor boards. It will click/knock on opposite sides alternatively. It has gotten quite cold in athens, ga within the past week or so but i dont think that should cause this knocking noise that i have been hearing... anybody have some insight into what this could possibly be?

[Bmeister]

If it is a series of light clicks/knocks, it probably just your HVAC system adjusting as the car begins to warm up. I don't like all the automated HVAC controls in any of my upscale vehicles but I guess that's the "price" we pay.

[harryd14]

ok, how long should these typically keep going on for? ill have to pay attention next time but i feel like they went on for a few minutes but i could very well me mistaken...

[Bmeister]

When cold, it may click a few times at a few short intervals as the engine warms to operating temperature. Thereafter, I sometimes notice it when making a drastic change to the temperature setting or changing the ventilation from dash to floor or windshield vent. If you hear something other than some light clicks, like loud metal-to-metal, then the climate control system may not be the instigator.