Which coolant temp is correct?

[CarlOrton]

re: 2001 C2, 49900 miles.

 

Well, it's late spring here in DFW, so that means daily temps in the 95 deg range.

 

I've noticed that my coolant temp has been creeping up and staying up more than normal. Usually, it's between the 8 and 0 of the 180 mark, but this has been creeping up to the the right side of the 0 digit. Yes, it will drop down once in motion.

 

I then stumbled upon the "a/c hack" information where you can display certain sensor information on the a/c control panel.  The engine temp at the hottest point was at 105 deg C or 221 F.  Then I noticed on another forum that folks were saying a) the analog gauge is far from accurate, and b: the temp displayed on the a/c unit is different from Durametric values.

 

So, today I connected my Durametric, and sure enough, there was about a 2-3 deg diff between the a/c panel indication and the Durametric displayed value. When the a/c was showing 105 deg, Durametric said 102 or 215 F.

 

So, I'm more curious than anything. Does Durametric take sensor information from a point different from the climate control system?  Why would there be a difference otherwise?

 

Thanks helping me understand the workings a bit better.

Edited June 10, 2016 by CarlOrton