I live in a mobile home. I have a new 3 1/2 ton package unit-all outside/ Today the weather was really nice so I turned off the unit at the Thermostat and opened the windows. But I heard something and went to check. The fans on the outdoor unit are still running. It will not turn off. The thermostat is set on Auto for the fans. But where is says Cool off heat - I moved it to off. I finally had to go to my electrical panel- find the AC fuses and flip the main off. What can I do...

Your fan might be wired to the wrong side of the contactor. If the comperssor was NOT running when you had the outside fan running then someone replaced the outside fan motor at one time and wired it to the wrong side of the contactor.

Now if the compressor was running along with the outside fan when the A/C was turned off on the thermostat then you have a wiring problem with the thermostat.

Now to clairfy what I mean is the fan that spins outside that blows the air out of the a/c unit outside not the fan that blows air inside the home. If that fan was the one running then you have a bad relay or the thermostat is wired wrong.