I have a Trane XL16i. The outside unit is a 4TWX6036C1000AA. It has a 5 amp ATO fuse in the low voltage control circuit that blew last night. The fan runs, but the compressor won't. The Tech came out and replaced it, it blew again. He could not figure it out and is waiting for the main tech to get back tonight and will try again tomorrow.
Based on the diagram this fuse is inline with the red wire from the 24 volt transformer on the outside unit and goes to the main circuit board connector J1.