How can you fix a car air conditioner that puts out a bad smell for 2 3 minutes when you first turn on the air conditioner?

You probably have mold forming on your condenser from precipitated water which has been left sitting, and thus has gone stagnant. Spraying the condenser and ducts with Ozium should do it. Most people spray it into the vent by the passenger door, but it's more effective to open up the HVAC compartment and go at it that way (if you know how).