Post [Q] Nexus 5 screen goes blank under lower temperature - 18 C

I have bought nexus 5 two months back. For the past few days I found my screen going blank for no reason. Later I found out this happens only when I am in air conditioned room. Room Temperature is normal (18 c or above). Do anybody have solution for this... Why my nexus 5 goes blank ???.. As of now I have reset my phone, no apps available. Android version - 4.4.2 preloaded.