lm35 interference microswitch

I use a sensor lm35 for temp in A0
and a microswitch “f83161.3” in A3 but i have interference and more when a micro switch “open”.

example when i use only lm35 i have temp 24 celsius (this is right)
when i use in my code lm35 and microswitch i have temp 16 celsius.
when microswitch open then temp up 30 celsius.

What could be wrong


No idea: we should see your code and circuit.

But seeing as it's an on-off switch, move it to a digital pin and maybe that will solve the problem?