My blows cold and I hear a clicking sound from the inside...what could it be?

The climate control panel has a lever that when you move it from hot to cold. It activates a servo. There are three servos and if a pen or candy, or sugary liquid gets down inside. It will jam the vent door that opens and closes to go from hot to cold. The clicking sound you hear is the servo. It is probably broken from trying to move the door that is jammed. This is what typically happens. I hope this information is what you were looking for. If there are other questions. Please write back, be specific and I'll do my best, good luck.

Bad actuator

same thing her call your dealer and say that u may have to bring it in to shop but..

The clicking sound you are hearing in the actuator for the vent door inside the hvac unit. Either the actuator is bad or the vent door has broken inside.

there is a "flap" like you say inside the blower box that mixes hot and cold air. in my 93 mustang this flap is controlled by a vacuum line, check for a vacuum leak? on a newer vehicle it may not be vacuum activated, but this flap is most likely the problem

This has the earmarks of a blend door actuator. It only blows cold until the thermostat opens because the blend door defaults to heat. The clicking you hear is a gear that has become stripped inside the actuator. To access this you will need to partially remove the dash.If you have more questions just leave a comment in my profile. Thanks.

the problem is in the blend door actuator, in this car, it is electric no a vacuum one, that's way it clicks , because the plastic gears inside the actuator brake , the door is in the heat position and wants to move the the cool position.. the solution is replace the actuator, if you are a handy person you can do it by your self..it doesn't require to discharge the system, just pull the trim panel and follow the click noise , they have two small screws holding it..hope this was very helpful..

Sounds like a compressor problem.

That sounds like the Blend Door Actulator has decided to go loopy. I heard of people turning it to hot and getting cold, Normally when this bit goes it makes a click click noise

Clump sound is probably the blend air door inside housing moving to where it's supposed to be. Is that when you notice it heating like it should? Try to pay attention when driving to see if you hear that "clump" noise or feel different temperatures as you accelerate, and then let of the gas, which would indicate vacuum operation of blend air door, and tells you that there is a vacuum leak somewhere in the system, or a perhaps just a faulty check valve in the line somewhere. let us know.