Help! A/C unit went out last night. Opened inside unit up (Trane XE80) and pulled the 5 amp blade fuse on the control board and saw that it had blown. Replaced the 5 amp fuse, closed the panel, and the blower started. When I went to turn on the A/C, the 5 amp fuse blew again (and again).

Main fuse box is not tripping, but replaced circuit breaker and 30 amp cartridge fuses in outside fuse box. Also replaced thermostat.

I can get the fan to work if I put in a new 5 amp blade fuse, and the LED will flash at regular intervals, but when I try to start either the heater or the A/C, it blows the 5 amp fuse every time.

Is the control board bad? Any other suggestions?