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Heat / HVAC on 7.0 - poor performance?

rdrcrmatt

Member
Jun 27, 2013
607
31
Milwaukee
Since I installed the 7.0 on my Classic P85 the Heat on the HVAC works like crap!

I turned on the defroster at 74 tonight and felt cold air blowing, the car used to warm up to the desired temp quickly and this time it took 10 minutes or so while driving (in 40* outside temps)

Here's a vid from last night when trying to really warm the car up quickly, just didn't make any sense. Watch the fan speed when I change temperatures.


 
Last edited by a moderator:

rdrcrmatt

Member
Jun 27, 2013
607
31
Milwaukee
I guess I'll give it a few more days before I cry about the slow heating times for normal temps. It seems as though the heater is just taking more time to heat on 7.0, but I HAVE NO DATA TO BACK THAT UP.
 

Forty Creek

Member
Aug 27, 2013
469
46
Carlisle, Ontario
I think they have tinkered with the fan speed relative to the temperature setting. I believe it will take some time under differing conditions to see if the net effect is better than pre 7.0. The claim is faster warm up using less energy. I would like to hear just how that is possible.
 

Majerus

Member
Jan 21, 2010
726
48
Illinois
Same problem, also had to turn it up to 85 before the vent stopped feeling cold. Also noticed my A/c compressor is kicking on very hard (makes a loud click when starting) after the update.
 

jdw

Supporting Member
Jun 1, 2015
695
1,332
Vancouver
Turning on defrost also turns on the AC, which makes sense on a warm day in the rain. Not so much to de-ice ... wonder if it takes the outside temp into consideration?
 

Kalud

Active Member
May 7, 2013
1,058
285
Montreal, QC
I've made numerous tests, the new system now target the temperature that you set precisely. If it overshoots then it cool down (hence the cold air that you fell, and its uncomfortable when its cold outside).

The previous 6.2 behavior was to heat and then if it overshoots just wait, so sometimes it was a bit hotter that the setpoint, like 2-3 degree Celcius above it. Now it aggressively corrects.

More tests needed but it seems that if you set "Range Mode" it avoid cooling down the heat overshoots (uses less energy).

Also they increased the accuracy of the temperature readout. In Celcius it was using 0.5 increment and it now uses 0.1C increment.
 

mknox

Well-Known Member
Aug 7, 2012
10,103
1,868
Toronto, ON
I've noticed two things:

One is that the setpoint is now closer to reality. Since getting the car 2.5 years ago, I've had to keep it set at 67 F to make the interior feel like 72 used to on every other car I've owned. After getting V7, I noticed it was cold in the car and had to bump it up to 71 or so and it seems to feel like it used to at 67. This is an improvement

The second is that the fan speed on Auto, which was too slow in the past, is now even slower. Without proper air circulation, I get bad window fogging. I keep my right scroll wheel set for fan speed so I can thumb it up or down as needed, and press to put the fan back in Auto. Looks like I'll continue to need to do that.
 

Chasedrgc1223

Nearly Insane
Apr 8, 2015
322
85
NJ
I disagree... On my 85D, climate control has become how I remember it in my Lexus. It's really a set and forget system now. I'm hearing a lot about pre-autopilot cars being negatively impacted, and I'd be interested to see why that is.
 

rodb

Member
May 6, 2014
30
0
Redmond, WA
+1
My heat is working very poorly after 7.0 upgrade. I took a drive into the mountains yesterday. Started off with just the seat heaters as the temp in town was mild. Started heading up and the temp started to drop so I turned the heat on and set to 68. The temp in the car kept dropping. after 30 minutes I turned the temp up to 75. in another 30 minutes the car was warm...not hot, not 75.
 

BriansTesla

Old school meets new tech
May 8, 2012
303
468
AI WA
This is fascinating! In my non-AP car, the heat used to take forever to start blowing warm air. It felt like an old air cooled VW.

With V7 it now seems much much better.
 

Todd Burch

Voltage makes me tingle.
Nov 3, 2009
7,980
30,395
Smithfield, VA
It could be that the newest software version relies more on the heat pump (more energy efficient, but slower to reach desired temperature) than resistive heating (faster to heat up but (much) less efficient). This might explain why it seems to be less effective at first, but at least some of you report that it's just slower to heat up.
 

CHG-ON

Still in love after all these miles
Jun 24, 2014
3,079
636
Santa Cruz Mountains, USA
As far as cooling, mine works better than ever. Still hot here in CA. I used to have to keep in recric and the fan blowing around 7-8 to feel comfortable. Now I am using auto and the fan seems to sit at around 2-3-4 and I am totally comfortable. And I am ALWAYS hot! I had the car at 70 last night and it seemed to work just fine. Not much air, but it felt fresh, and I wasn't cold. But then again. I am always hot :smile:. It was probably in the low 60's. Now I am curious and will test using more heat. I will say that my compressor seems a lot louder at low loads: more like it did when the car was 110 and I cranked it up to cool it down.

I think that what I read was that cooling was more efficient and better. Doesn't do much for our northern friends, unfortunately.
 

JenniferQ

Supporting Member
Sep 13, 2015
1,260
514
San Diego, CA
I find the cooling is working much better. It was cooler today, after stinking hot summer lasting way into Oct, and for some reason as we were driving the a/c flow switched to the floor vents and started blowing cold air on our feet. I had turned it up to about 75 to keep it from being too cold. But strange to read this thread after having that happen. I would have thought that if it diverted from cabin to floor it would have blown hotter air. Nope. Luckily, it was a perfect 72 (where have you been?) and we just opened the windows and the sunroof and all was well again. But, I think I experienced what you in colder climates are referring to.
 

apacheguy

S Sig #255
Oct 21, 2012
5,083
1,243
So Cal
It could be that the newest software version relies more on the heat pump (more energy efficient, but slower to reach desired temperature) than resistive heating (faster to heat up but (much) less efficient). This might explain why it seems to be less effective at first, but at least some of you report that it's just slower to heat up.

Thought the MS only had a heat pump. It has dual heaters? Seems inefficient especially considering the extra weight.
 

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