I've noticed over the past few months that my car warms up just fine but sometimes when I'm stopped at a light and begin to accelerate, my temperature needle goes all the way to cold for a few seconds but then eventually goes back to its correct position which is a little less than the halfway mark. I have a new thermostat and fan switch but am still having the same problem. My guess is it's the coolant temperature sending unit. Has anyone replaced it before? If so, is it easy to do? Thanks!

 

for a little bit my car was having a problem heating up randomly...at lights and stuff....took some things apart and found that my thermostat had gone bad and as jammed open.....i replaced that and it took care of everything

 

Thanks i3aog. The weird thing about my car is that it never goes above the halfway mark in temperature, it just drops all the way down to cold randomly. I had my dealer check it out and sure enough on the way there it happened and my check engine light came on as well. They checked it and said they couldn't find anything wrong and that no codes had been stored, even though my check engine light had just come on.

 

My integra is doing this right now so I ordered a new thermostat to see if that fixes it. If it doesn't, then I'll be in the same position you are currently in.