What is that loud ticking sound in my home air condition?

What is that loud ticking sound in my home air condition?
It sounds sort of like a fan would sound when something is in it's way. A constant loud quick tick. I opened the ac and watched the fan. The sound did not start till a while after the fan had been circulating, so its not the fan (I think). It is so loud I cannot use the ac. What is it and what should I do? I did. The sound starts after the fan has been blowing for a while. The sound does not happen when I turn the wheel


Answers:

lloyd:  Something in the duct work may have come lose and is hitting the blower. Turn the power off and spin the blower wheel by hand and see if the sound is still there. I have seen the info tag that is glued to the inside the blower housing only glued on one side and the lose end hits the blower wheel. Make sure all of the wiring is tight.
2009-08-10 19:06:37
nedree@verizon.net:  check to see if one of the blades out of line.(bent)it may happen only when it is at full speed.good luck.
2009-08-10 19:50:54
Chosen Answer
Dubidiocho:  Ironically I just noticed my heat-pump doing the same thing. In my case a wrap of insulation tape used to wrap components in the unit has come loose and the fan sucks it up in it's path at random times. I'm going to shut off the power switch and do a tape-ectomy surgery soon!
2009-08-10 19:59:42