I have a Honda Accord 1999?

I bought freon for my Honda Accord 1999 and I put the freon to the limit it was supposed to be and I turned on the a/c there was a hissing sound but only when the car was at a red light or stop sign I the car is moving the hissing sound goes away what can it be?

Sell it! And i PROMISE! It will GO AWAY!

Don't run the A/C until it is serviced by a professional. It is probably overcharged - it is impossible to determine state of charge with a gauge - and the compressor will be quickly destroyed if run with much of an overcharge.

Get it serviced by a professional. First off if you are putting freon in your car and it's post 1993, you're breaking it. Although that's not likely the case because there should be no way to get your hands on freon. Freon refers to R-12 refrigerant, which doesn't run in any vehicle 1994 or later. You should have put in R-134a (which I'm assuming you did but are just incorrectly calling it freon) Additionally you should be measuring the amount of refrigerant in a refrigeration cycle by weight. Put the bottle on a scale, connect it to to fill location and crack the valve and watch the weight of the bottle decrease by the amount of refrigerant your system was designed for then close the calve and remove the bottle from your ac system.

Moral of the story… Get it done by someone who knows what they are doing

That hissing sound you've heard is from the freon being released by the release valve, either the system is overcharge or the head pressure is too high in the system due to the fans are not running or such.

How much did you put in? The specification for the system is 16-17.6 ounces. This video will show you how:

Other answers were right, if you have doubt, get someone who know how to work with AC system before you have to pay for another hose or compressor. HTH