voltage referance 586KR

i use uno, , loving it.
my question concerns incorrect/variable readings lm35's.
i have used example sketches smooth/average readings taking issue may other.

i have 3 sensors up/down buttons control on/off temp fan relays displayed on lcd

i have 3 separate boards: paralleled power wall unit before final install in truck
board 1 contains:
12vdc in 7805
3 relays each driven 3904
3 lm35 sensors on 24" leads mounted aluminum casing of audio amp

board 2 contains:
12vdc 7805
standalone 328p 16mhz crystal
3 led outputs board 3
3 relay outputs board 1
3 temp inputs board 1
button read input board 3
20x2 lcd ribbon board 3
5v supply board 3

board 3 contains:
20x2 lcd 10k pot
6 buttons on resistor ladder


everything works great except when test set limits on lm35's.
if 1 relay kicks on, temp readings 3 jump 2 degrees. kick in realy, 2 more degrees , 3rd relay, 2 more degrees.  readings drop relays turn off
the initial temp lm35's accurate comparing separate temp unit have.

i can check voltage @ lm35 , varies .01v when relays kick in , out.
i have tried internal aref 1.1v
i have used external 5v
i have seperated lm35 grounds
all above still jump when relays kick in.

i upload .ino and/or .sch files if verify
not important killing me not knowing going on , why

forgot ask main question (stupid me)

to use 586kr 5v ref smd ic make difference 328p aref???
use 3rd 7805 lm35's???

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