Temperature display on the HVAC module

[Deleted member 9692]

You're saying that it's freezing cold at 25 and sweating at 26. That's not just a labelling shift or offset.

I don’t know what you mean by labelling shift. There has been much previous discussion on this fault and my issue seems the same to me as many others have reported

 

[Rolfe]

What I mean is that on my car the system would be just fine if the numbers on the display were all 5 less than they actually are.

You seem to have an actual fault. It's not normal to be freezing at one temperature and sweating one degree higher.

 

[Deleted member 9692]

What I mean is that on my car the system would be just fine if the numbers on the display were all 5 less than they actually are.

You seem to have an actual fault. It's not normal to be freezing at one temperature and sweating one degree higher.

Understood. The majority of posts I have seen on this previously over many months seem to have same issue as me, yours appears different. There are many other posts with issue like mine eg This one There are clearly variations of the problem.

 

[Rolfe]

Indeed. I haven't had an issue with being able to get a comfortable temperature and my system seems to go in gradual increments up the scale. My only issue as far as I'm aware is that the numbers are wrong. I was curious as to whether all cars showed from 18 to 32, or whether cars that seemed to report the right temperature were showing a different range. So far, no definite reports of anything other than 18 to 32.

 

[Deleted member 9692]

Indeed. I haven't had an issue with being able to get a comfortable temperature and my system seems to go in gradual increments up the scale. My only issue as far as I'm aware is that the numbers are wrong. I was curious as to whether all cars showed from 18 to 32, or whether cars that seemed to report the right temperature were showing a different range. So far, no definite reports of anything other than 18 to 32.

I will check the range on mine later. When I first got my car I was running it at 21 or 22 as in every single other car I’ve ever had and I thought I had a serious medical condition for a while. Sooooo cooold . My dealer tells me they have just replaced the ”whole HVAC” system in another MG4, please God mine is just a ‘stat

 

[Lucky5]

I run at 23/4 in the MG4 and that is comfortable but 20 in previous cars. The temp in the MG4 is +VAT

 

[mg4mc]

TLDR: I think the internal temp sensor is fairly accurate - from one data point.

I decided to check the interior temp sensor on my car. External reading was 21C, internal 25C.

I played around with the climate control, and it seemed to switch over from cooling to heating with the fans going quiet at 25C.

There was no sun in the drivers area, so I opened both doors to let a through draft. After a while, both internal and external temperature sensors are reading 21C.

My weather station was reading 18.9C at the time, and a thermistor in the car (in the breeze) was reading 18.2C

An IR reading from the plastic area around the internal temp sensor was showing 22C - but I'm guessing on what emissivity value to use.

As there will be quite a lot of thermal mass in a car which was still partially in the sun, and had been in more direct sunshine earlier, the slightly elevated temperatures from both sensors could be expected.

From this one data point, the internal temp reading seems to reading correctly.

What I will do is check again later tonight when the sun has gone down, and temperatures have dropped. I expect the internal temp to read much higher than ambient at that time. But I'll leave the doors open and see what happens....

 

[Rolfe]

I wrote a post elsewhere about the weird behaviour of the internal temperature sensor as reported by the app. That always seems to start higher than the truth, and as you keep re-scanning it, it gradually gets more plausible. Except for the times it reports 87C of course. It's possible only the SE does this. I'll see if I can find it.

Yes, here, and following.

Do you think it's safe?

Do you think it's safe to get in the car🤔

www.mgevs.com

It was because nobody seemed to be responding to that thread any more and I was still curious about what was going on that I started this one. I kind of think the weird behaviour of the internal temperature on the app and the apparent over-reading on the screen are possibly two different things.

 

[fnegroni]

Resuming an older thread.
Previously I mentioned my HVAC setting seemed to be off by 3 degrees.
If I set it to 21, the internal temperature would be 18, set it to 22, internal temp 19 and so on and so forth: set it to 25, interior temp is 22.
Or so I thought. Last night it was set to 26 degrees and instead of what I expected the internal temp to be 23, it was dead on 26!
Set it to 25C you get 22C
Set it to 26C you get 26C
the only difference I noticed is that when it’s set to 25, the HVAC is still occasionally blowing air through the front vents.
When set to 26C, the front vents aren’t used anymore

So now I have it set to AUTO, but I exclude the front vents.

I’ll test this over the next few weeks but I wonder if the logic in the HVAC is not taking into account the cooling effect of the front vents and struggles to keep the heater and A/C to balance out.

 

[Kithmo]

Mine goes from 18-32C in between LO and HI, it's blowing just warm at 25C and toasty at 27C, but it never gets time to fully warm the cabin on my 10 minute each way journeys every day.
24C blows cold air for the whole 10 minutes.
IIRC my 2016 Prius used to go from LO-16 to 32-HI but 19C was warm (eventually when the engine warmed up).
Either way cranking it up to blow more than just warm air results in severe loss of efficiency for me on my short journeys, but I accept that, after all it was the same with the Prius, worst tankful in severe Winter weather was 30mpg, best tank in Summer was over 65mpg. If I want to be warm, I have to pay for it.