heater/ac knocking noise
 

i have 2000 tl with 71000 miles. when i start the car i hear a knocking noise that is related to heating/cooling system. i located the part making the noise - right in center of car, under dash, next to firewall. the part # is 79160soka 0024a. the knocking sound goes away after a couple of minutes. i felt the knocking in the part and it feels like its trying to open a vent or something.

Knocking under dash
 

I have the same problem, but the part number you listed for the fix does not come up anywhere as an Acura part number. Is there another number?

sounds like the air mix motor maybe. mines made noises like that. when you turn on full blast heat or a/c it tries to open/close the heater valve. i think the cable for it is out of adjustment and the motor cant move like its supposed to. dont have a part number handy but its located in the passenger side footwell just beneath the radio. look for a black box with an arm connected to it

It's motor assy air mix, part# 79160-s0k-a01. Try to jiggle the stainless steal rod behind the firewall. open up the hood, on the passenger side, look down carefully, just below the glove compartment, you will see the rod goes to the heater valve, jiggle it and see if that helps.

its very hard to explain but if you look under the dash on the pass side right next to the console there are little whits arms that pivot when you turn the climate from hot to cold. Thats whats making the noise.

Air Mix Motor Noise
 

Under the hood, near the firewall a cable and a water house meet in a valve. The valve has a small lever arm which can be worked by one's finger. This moves the cable to the air mix motor. By moving the lever, I could cause the clicking to start or stop. When working that lever, I noticed there was a point where the cable caught and made the clicking noise. I sprayed some grease on the cable and worked it repeatedly until the cable moved smoothly. It remains to be seen whether this is a permanent fix, but so far the noise is gone.

Welcome DavidThayer !!!
Yeah, sometimes the cable tends to stick and lubing it will help.
However, if the "clicking" noise continues, there's a "DIY" for flipping the gear on the air mix motor.
It develops a wear pattern on the teeth and slips. Enjoy the site and happy reading !