My outside a/c unit just quit working. I had a problem with my disconnect box last year because it was rusted real bad etc... So, I bought a new one and changed it out. No problem. But my unit still doesn't come on outside when my system comes on in the house. Could my motor in the unit be the problem? I'm not a tech in this field of work but I am a computer tech and I've done some minor electric work before in my home.

Inside the service access panel of the outside unit there will be an item called a contactor. Using a insulated item push in the contacts and see if the unit comes on. If not check for defective fuses in the outside disconnect you replaced if so equipped and also check the inside panel to make sure the breaker is turned on for the outside unit.

If the unit comes on outside when you activate the contactor with a insulated tool then the problem is with the low voltage signal circuit from the inside unit to the outside unit. The contactor looks something like the attached pics.