Thanks, I found the 32:8, but couldn't work out the 80 in the checksum.

I had to make a couple more changes to get the aircon to respond, not sure if its model specific or not however -

38.0k,412 and -4 at the end.

So far getting some responses from the AC!! but not for all code changes are working - will keep investigating.

Thanks for the feedback!! :)

[protocol]
name=Fujitsu Aircon2
irp={38.0k,412}<1,-1|1,-3>(8,-4,20:8,99:8,0:8,16:8,16:8,254:8,9:8,48:8,H:8,J:8, K:8, L:8, M:8,N:8,32:8,Z:8,1,-4)+ {H=16*A + wOn, J=16*C + B, K=16*E:4 + D:4, L=tOff:8, M=tOff:3:8+fOff*8+16*tOn:4, N=tOn:7:8+128*fOn,Z=256-(H+J+K+L+M+N+80)%256} [A:0..15,wOn:0..1,B:0..15, C:0..15,D:0..15,E:0..15,tOff:0..1024,tOn:0..1024,fOff:0..1,fOn:0..1]