I have 6ton carrier condensing unit. Normally when the ac demand starts, the fan kicks to high speed and after 5 minutes or so, the compressor should kick in. now as soon as I flip on the disconnect, the condensing fan starts as very slow speed and 5 minutes later the compressor demand is at that time the fan takes off at high speed. After 5 to 7 minutes the condenser unit stops and the fan motor goes back to slow speed. I hope I'm making any sense.

What type of unit is this? Is it a roof top or self contained unit? If it's a split system, I believe you can only get up to a five ton condenser. Something sure sounds strange here either way. This most likely is a problem that will require an onsight evaluation by a professional. Sorry I can't be of more help here. Take care, and please let me know the outcome.