Kelvinator KSR25 blowing pcb fuse

Hi guys,

went out to look at a domestic Kelvinator split system air conditioner last week. When I turned up the fuse on the indoor PCB was blown. I replaced it to see what was happening and the indoor unit powered up, the louvres opened and the fan started to blow air. Around 30-45 sec later it blows the fuse on the indoor PCB.

Main power (240V) is supplied to the indoor unit and then control wires to the outdoor condensing unit. I went out and tested the relays on the outdoor PCB as I thought it seems as though when the compressor is trying to kick in its blowing the fuse. Found one of the relays on the outdoor PCB to be dead so I ordered a new board - easy fix I thought!

Fitted the new board today and its still blowing the fuse after 30-45 seconds! I put my multimeter over the condenser fan wires and it looks to be ok - and then did the same with the compressor windings which also appeared fine.......any suggestions???

sorry for the long post but its doing my head in as I need to get it fixed before I head away interstate for long term work.

thanks people,

Russell