My force air unit is manufactured from Goodman (Model CKL30-1L). The controller is on the attic. The fuses do not blow when it is switched to heat and the unit runs fine. However, when switching to A/C, all the fuses blow. Please advise for the problem.

Sounds like you have a major short in the electric going to or servicing the outside condensing unit. You will need a meter and check for shot=rt circuits. It could also be your compressor shorting out. Have you done any work to or changed anything in the unit lately?

A CKL30 is just AC only and if you blow the fuse when you turn it to cooling, you most likely have a problem in your condensing unit. It's probably a bad condenser fan motor or compressor.

The unit is less than 2 years old. In the winter of 2005 when the unit was still under 1 year warranty, the heat did not work and was repaired by the builder's contractor. It has been working OK until now. I did not touch anything, excepting checking for the fuse according to Goodman trouble shoot.

Check the low voltage wires on the outside of your house going to the condensing unit. Could be a dog chewed the wires or the weed eater got into them.

My force air unit is manufatured from Goodman (Model CKL30-1L). The controller is on the attic. The fuses do not blow when it is switched to heat and the unit runs fine. However, when switching to A/C, all the fuses blow. Please advise for the problem.
I've same problem. lnguyen1, you have found the solution yet?

Looks like your contactor inside the outside ac unit is bad. You can check it with a multimeter. It will cost $10~90 if you replace it by yourself, and > $300 if you ask for the contractor.