Random display temperature reader LM34 and 7107
I'm not convinced the schematic posted can work as is. The reason is that for 2V (full scale) operation the ICL7107 datasheet indicates you need to use dual supplies, i.e. tie pin 26 to a -5V source.  The ICL7107 can work on a single (+5V) supply but there are some complex conditions/requirement on page 10 of the datasheet. I'm not convinced your circuit meets them. The most important is that "An external reference is used." They suggest an ICL8069 in that role (see fig 16 for an example, but beware that's setup for the 200mV scale as well). Or you can use/generate a dual supply (use the schematic suggested on p. 10 if you want to generate it).



Now it's entirely possible someone discovered it works like in the schematic you posted  (single supply and no external ref) anyhow, but I wouldn't hold my breath. I don't have one ICL7107 handy to test myself right now.

The first schematic[s] I found while googling this, on instructables strengthen my suspicion in unsuitability of the one you posted... because both of those I found generate -5V for the ICL7107 (albeit in different ways). So you're better off trying one of those, as they are more in line with the datasheet recommendations. This is what they look like:




Good luck.