My a/c keeps blowing the 3 amp fuse on my furnace. I tried the heat on the furnace and it works just fine. However, when I switch to the a/c, it blows the 3 amp fuse immediately. N ever had a problem with the a/c in the last 10 years and now I have this problem.

Check low voltage wiring to outside compressor unit. You probably hit it with the weed whacker or the dog chewed it up.

Could be a contactor

I got got the furnace blower to work on the cool on cycle, but the air conditioner compressor or the outside fan does not turn on. Still not getting cool air. Thermostat indicates air is on, but air compressor & outside fan does not turn on.

As said before, check the low voltage wiring between furnace and condenser for breaks /shorts, if OK the contactor coil might be shorted and needs replaced

How do you check the low voltage? What reading am I looking for on the voltage. I have a couple of thin wires going into the box outside. Are those wires the low voltage wires?

Yes,, the small wires,should be 24 volts reading at the contactor connection,, be careful /kill the high voltage power if you are unexperianced

I can pull the circuit breaker on the outside of the house. Do I need to turn off the circuit breakers in the basement as well? I have 2 switches for the a/c in the fuse box in the basement

That will work, don`t want you getting shocked

Remove power to the outside and inside units. Disconnect both small wires going to the contactor and cap. Turn on power to both. Get a call to cool. Wail at least 5 minutes (Thermostat has anti-short cycle built in usually). See if fuse blows.

If it does, then disconnect those same wires (Y and C) at the furnace and repeat.