Central Air - Goodman
Furnace - Tappan
Thermostat - Robertshaw (Programmable)

I keep blowing a 3 Amp fuse that is located on a computer board inside of my furnace panel when turning on the Central Air unit. I've replaced the fuse and was able to run the furnace and the blowing fan just fine, until I turn the AC on. This blows the fuse and the furnace, blowing fan and AC all cease working. Replace the fuse and furnace and blowing fan work fine. Went outside and made sure fan on AC unit was freely moving and it was fine. Threw breaker in my house electrical panel to the AC unit and switched thermostat to cool mode and blew the fuse again. So I think I've found out that the outside unit is fine, if I'm blowing the fuse when the power to the AC unit is off?? Do I have a bad transformer inside the furnace?

Thanks in advance for the help!