2018 Ram Promaster Thermometer

[Tom 98072]

My thermometer fluctuates radically as much as 10 degrees. Any ideas?

[MsNomer]

Is this the ambient thermometer on the driver mirror? If so, it is easily skewed by sun on the black housing.

[Tom 98072]

The one that provides data to the dashboard. It isn’t sunlight effected, t always reads cold.

[MsNomer]

Yes, that is in a little nipple underneath the driver mirror. If you are still under warranty, make them fix it. Except for heating up in the sun, it it normally quite accurate.

[booster]

If the OP is referring to the sensor that would control the automatic temp control for the chassis heat/AC system, I don't think that sensor would be on the inside mirror itself in most vehicles as it would see sun and be too high in the cab. Most of the diagrams I have seen place it in a return air duct or in the dash area to best read the temp level the front seat passengers see.



If the "driver mirror" is the outside mirror on the driver's side of the vehicle that is a possible location for the outside temp sensor which also has an input to the heat and AC controls. I would expect there are probably two sensors, one outside, and one inside to control the climate control and that either could cause a problem. If the exterior temp readout in the van is reading incorrectly the outside sensor is probably bad and would start with that one. Most outside sensors I have seen are up under the front bumper somewhere, so if it is in the mirror you might have to buy a complete mirror to replace it.

[mloganusda]

Here is a fix to replace the outside temp sensor. You have to replace the whole mirror, as mine was replaced under warranty. This is from the Pro Master forum.
https://www.promasterforum.com/threa...7/#post-744092

[MsNomer]

I have no idea about the thermometer for heater/ac, but the thermometer that reads on the dash is underneath the driver mirror on the PM.

[Tom 98072]

Thanks to everyone for your posts.
I am talking about the outside temp. I should have thought of the mirror because I have gotten a Brandmotion mirror with front and rear cameras.

[MsNomer]

Originally Posted by Tom 98072

Thanks to everyone for your posts.
I am talking about the outside temp. I should have thought of the mirror because I have gotten a Brandmotion mirror with front and rear cameras.

To be clear, I'm talking about the outside mirror on the driver side. The big one hanging off the door. Not the inside rear view mirror.

[Urlauber]

Originally Posted by Tom 98072

I have gotten a Brandmotion mirror with front and rear cameras.

How do you like the LCD mirror? I am thinking about getting one, but I have the dash display so maybe there would be overlap, plus all the issues with not turning off and emptying the battery.

[JohnP]

I just recently posted a tutorial on the Facebook Hymer Aktiv Owners and Wanabees group for how to to replace the sensor inside the mirror housing. The alternative is to replace the entire mirror which will cost hundreds of dollars. You'll need to join the group to see the post along with photos. I'm traveling now and can't repost it here.