old Manitowoc blowing control fuse

I have a Manitowoc m#GRO600A that keeps blowing glass fuse on control board. When toggle switch is put in water circulation position, unit runs fine. When toggle switch is put in ice position, there is a loud pop and a blown fuse instantly. Cannot find anything grounded or shorted. Ice sensor relay looked burnt. Installed new unitary board/sensor relay assembly. Installed inline fuse before terminal #4 on board. Same problem. Tried disconnecting condenser fan motor (even though fan cycle should isolate). Same problem. Checked voltage rating on solenoid coils - both coils ok. Found about 500 ohmes through hot gas solenoid coil and dump valve solenoid coil. Voltage supplied to unit is 247v. Checked to make sure all wiring is in the correct place. Suspect there is a short between L1 and L2 somewhere. Breaker hasn't tripped yet. Any ideas?

There's not much on these units, disconnect all solenoids, have you checked contactor feeding compressor?

al

Al, I have replaced the compressor contactor due to pitting and to eliminate one more component.

I would start by disconnecting things one by one until I isolate the problem. Start with the compressor.

I have it repaired now. it was shorted condenser fan wire (dry rotted). Thanks for your help.