Most likely you have a damaged - locking a/c compressor internally.............
Your bike may be making a clunking noise when you pedal due to issues with the chain, pedals, bottom bracket, or other components that may be loose or worn out. It is recommended to have a professional bike mechanic inspect and repair the bike to prevent further damage.
Remove the compressor and pour it in. If its making noise its probably to late and you will need to replace it.
theres is to many things that could becausing it, so its hard to tell. the best thing to do is jack both front teires off the ground and try to wiggle the tires back and forth, there should be no play (or movement).
Check you E-Stop Brake on the rear.
god Zeus is in charge of making thunder
Chain alignment is off between the freewheel and front chainring. Also check chain tension when installing the back wheel.
You could have a starved CV joint. Take your blazer to a wide-open space (i.e., vacant parking lot) roll your windows down and turn the vehicle in tight circles in both directions. If the noise is present have a mechanic check your CV boots/joints.
It means that the compressor is broken inside, and it is time to replace it.
It sounds like you have a very tight running or bad a/c compressor since most all systems will engage the compressor when the defroster is on...............
Probably something is loose or worn... sorry to not be more specific, but you'll need to track it down to see WHAT is making that noise.
before you get to the turning point ! ! haha
Sounds like the compressor is shot and it would be best to replace both. Unfortunately when the compressor goes bad it sends metal trash throughout the system. If you replace the compressor with out having the system flushed clean (which is almost impossible to do) the trash in the system will eventually destroy the new compressor.