Tarting a business servicing air conditioning residencial,commercial walk-in coolers do I need a bond or insurance?

Depends on where you are located. Here as long as you never do work over $500 you do not need a bond or insurance or a contracters licence. Just you CFC card and a business licence. I would still recommend getting some sort of insurance. Even if not required.

Do you want to run a good business, or a fly by night business? The only way to start a good business in this trade is to be bonded and insured. I promise you will be doing way over five hundred dollars worth of work at one job or another. I wish you the best of luck in your new business. Please let us know how it goes.