Any tips for stop & go traffic in 85F heat?

djett

Well-Known Member
Joined
Nov 5, 2020
Threads
15
Messages
124
Reaction score
179
Location
CT
Vehicles
Mach E Premium AWD
Country flag
Came back from Boston yesterday and traffic was worse than usual on the Mass Pike due to impending doom (aka Hurricane Henri). Traffic was stop & go for about 15 miles. It was relatively hot (85F) and very humid. I was watching the external temperature on the screen creep up. It got up to 100F. It was not 100F outside. I also noticed the interior of the car was getting warmer. At the next exit I jumped off the Mass Pike and took a different route home. As soon as I was out of stop & go traffic and back to normal highway speeds the external temp came back down to the actual outside temperature and the cabin cooled back to normal.

Are there any tips I should know if I'm in this situation again - and not able to exit stage left?

 

JamieGeek

Well-Known Member
Joined
Dec 29, 2019
Threads
81
Messages
3,355
Reaction score
6,384
Location
Southeastern Michigan
Website
spareelectrons.wordpress.com
Vehicles
Mach-E, old: Bolt, C-Max Energi, Focus Electric
Country flag
Just drive: the car can regulate its own temps.

Did you press the "Auto" button to max? (there are 3 auto levels--first car I've had with 3 auto levels).

Personally I would have put on the intelligent cruise and just let the car drive itself with the HVAC on high.
 

Mach-Lee

Well-Known Member
First Name
Lee
Joined
Jul 16, 2021
Threads
43
Messages
1,318
Reaction score
2,081
Location
Wisconsin
Vehicles
2022 Mach-E Premium AWD
Occupation
Sci/Eng
Country flag
Yes, you are worrying about nothing. People in AZ are driving the car in 125ºF temps with no problems.

The outdoor temp sensor is in a location that is sensitive to thermal radiation, if you're moving less than 25 mph the reading is inaccurate. It can read up to 20ºF higher than actual while stopped in some cases.
 

GoodenoughIsGod

Active Member
Joined
Jul 2, 2021
Threads
5
Messages
35
Reaction score
19
Location
MA
Vehicles
Nissan Leaf
Country flag
Yes, you are worrying about nothing. People in AZ are driving the car in 125ºF temps with no problems.

The outdoor temp sensor is in a location that is sensitive to thermal radiation, if you're moving less than 25 mph the reading is inaccurate. It can read up to 20ºF higher than actual while stopped in some cases.
I get what you're saying. When the car is moving, at higher speeds, convection is more effective and the temperature the temp sensor reads is closer to the true ambient temperature. However... if the sensor is reading a higher temperature than actual, it means the HVAC control system is getting a faulty input and probably working harder than it should be. Shouldn't the temp sensor reading be adjusted for car speed?
 

Mach-Lee

Well-Known Member
First Name
Lee
Joined
Jul 16, 2021
Threads
43
Messages
1,318
Reaction score
2,081
Location
Wisconsin
Vehicles
2022 Mach-E Premium AWD
Occupation
Sci/Eng
Country flag
I get what you're saying. When the car is moving, at higher speeds, convection is more effective and the temperature the temp sensor reads is closer to the true ambient temperature. However... if the sensor is reading a higher temperature than actual, it means the HVAC control system is getting a faulty input and probably working harder than it should be. Shouldn't the temp sensor reading be adjusted for car speed?
There are many inputs to the HVAC system, including system pressure, sun load, interior temp, evaporator temp, and top and bottom air discharge temp sensors. Since the actual output is measured carefully, I don't think a bad exterior temp sensor reading will cause any problems, the system will adapt for it. For A/C, the system is mainly focused on maintaining a desired evaporator temperature.
 


GoodenoughIsGod

Active Member
Joined
Jul 2, 2021
Threads
5
Messages
35
Reaction score
19
Location
MA
Vehicles
Nissan Leaf
Country flag
There are many inputs to the HVAC system, including system pressure, sun load, interior temp, evaporator temp, and top and bottom air discharge temp sensors. Since the actual output is measured carefully, I don't think a bad exterior temp sensor reading will cause any problems, the system will adapt for it. For A/C, the system is mainly focused on maintaining a desired evaporator temperature.
That makes sense. Thanks!
 

Badger_Prof

Well-Known Member
First Name
Randy
Joined
Jun 22, 2020
Threads
4
Messages
759
Reaction score
1,523
Location
Wisconsin
Vehicles
Prior--Leaf,Bolt EV. Mustang Mach-E Premium AWD ER
Country flag
There are many inputs to the HVAC system, including system pressure, sun load, interior temp, evaporator temp, and top and bottom air discharge temp sensors. Since the actual output is measured carefully, I don't think a bad exterior temp sensor reading will cause any problems, the system will adapt for it. For A/C, the system is mainly focused on maintaining a desired evaporator temperature.
Isn't the AC tasked primarily with maintaining the set interior temperature? If so, is the outside temp even relevant for the interior temp the AC will attempt to provide? I understand the AC will need to work harder/longer to maintain the interior temp if it is hotter outside but I am not sure the AC system is attempting to maintain anything other than the set interior temp.
 

ARK

Well-Known Member
Joined
Aug 21, 2020
Threads
27
Messages
1,964
Reaction score
2,866
Location
Los Angeles
Vehicles
Mustang Mach E
Country flag
Isn't the AC tasked primarily with maintaining the set interior temperature? If so, is the outside temp even relevant for the interior temp the AC will attempt to provide? I understand the AC will need to work harder/longer to maintain the interior temp if it is hotter outside but I am not sure the AC system is attempting to maintain anything other than the set interior temp.
Agreed, I don’t think the outside temp reading is tied to HVAC.

Query whether the battery cooling systems make use of it in some way, but HVAC is based on the settings the driver sets the cooling or heating to.
 

Mach-Lee

Well-Known Member
First Name
Lee
Joined
Jul 16, 2021
Threads
43
Messages
1,318
Reaction score
2,081
Location
Wisconsin
Vehicles
2022 Mach-E Premium AWD
Occupation
Sci/Eng
Country flag
Isn't the AC tasked primarily with maintaining the set interior temperature? If so, is the outside temp even relevant for the interior temp the AC will attempt to provide? I understand the AC will need to work harder/longer to maintain the interior temp if it is hotter outside but I am not sure the AC system is attempting to maintain anything other than the set interior temp.
The outside temp is really only used to decide if the A/C compressor can run, AKA that it is above freezing (32ºF) outside. Next the system looks at the interior temp and decides if it's near or above set-point like your home thermostat. If so, then it will run the A/C, and the compressor speed will be varied to maintain whatever desired evap temp the system finds necessary to produce the desired discharge air temps (humidity control is also a factor). Evap temp is the main feedback for compressor speed, since the airstreams may be separately warmed for dual zone temp control.

So I guess to summarize–compressor maintains desired evap temp, and the whole HVAC system maintains desired cabin temp and humidity. Outside temp is not that important.
 
OP
OP

djett

Well-Known Member
Joined
Nov 5, 2020
Threads
15
Messages
124
Reaction score
179
Location
CT
Vehicles
Mach E Premium AWD
Country flag
I hadn't changed the Auto from anything other than lowest setting. Good to know.

So it sounds like the exterior temperature misread should not have caused any problems. Either overall with the cars performance or with the interior temperature. But I felt the interior was getting warmer - hard to describe but something was getting hot near the steering wheel. Once I was back up to regular speed that all dissipated and I could distinctly feel the interior get cooler.

I know that other areas of the country are definitely hotter than it was here yesterday. Which is why I figured there was just an adjustment I should have made....

As always, I appreciate this forum for these exact types of discussions!
 

macchiaz-o

Well-Known Member
First Name
Jonathan
Joined
Nov 25, 2019
Threads
155
Messages
6,430
Reaction score
12,751
Location
Valley on the Sun 😰
Vehicles
Premium RWD SR
Country flag
I hadn't changed the Auto from anything other than lowest setting. Good to know.

So it sounds like the exterior temperature misread should not have caused any problems. Either overall with the cars performance or with the interior temperature. But I felt the interior was getting warmer - hard to describe but something was getting hot near the steering wheel. Once I was back up to regular speed that all dissipated and I could distinctly feel the interior get cooler.

I know that other areas of the country are definitely hotter than it was here yesterday. Which is why I figured there was just an adjustment I should have made....

As always, I appreciate this forum for these exact types of discussions!
Also consider the direction of the sun relative to your driver side window. If the sun was baking your steering wheel until you left the Mass Pike and headed in a new direction or trees/buildings obscured the sun's radiant heat, then this will make a marked difference on how hot it feels for you as the driver.

A smaller thing, but your stress/anxiety also went down when you changed roads, and that will help you cool down and be more comfortable.
 

SnBGC

Well-Known Member
First Name
Greg
Joined
Apr 20, 2020
Threads
42
Messages
4,735
Reaction score
7,859
Location
Phoenix
Vehicles
2021 Mach-E FE, 2021 Wrangler 4xe High Altitude
Occupation
Manager
Country flag
Came back from Boston yesterday and traffic was worse than usual on the Mass Pike due to impending doom (aka Hurricane Henri). Traffic was stop & go for about 15 miles. It was relatively hot (85F) and very humid. I was watching the external temperature on the screen creep up. It got up to 100F. It was not 100F outside. I also noticed the interior of the car was getting warmer. At the next exit I jumped off the Mass Pike and took a different route home. As soon as I was out of stop & go traffic and back to normal highway speeds the external temp came back down to the actual outside temperature and the cabin cooled back to normal.

Are there any tips I should know if I'm in this situation again - and not able to exit stage left?
The exterior temp sensor is inside the front compartment with all the electronics, radiator, fans, motor etc. The temp reading matches the actual temp in that space but may not be actual ambient outside the vehicle. Took us a while to come to terms with that variance. So, that reading on the SYNC screen doesn't really have much value to the driver other than we know how hot it is under the hood and front compartment area. When I first got my car, I used that front compartment for groceries but once summer started, I put my groceries in the back because it is so hot under the hood.

Your experience is pretty much what we deal with out here all summer. I tinted my front door glass and a header strip across the top of the windshield and that made a huge difference. Prior to the tint, I would need to run Mac A/C to get the cabin temp cooled down enough so I was comfortable and then switch to Auto 3 setting. In that setting, the cabin temp would be maintained even when ambient temps were 115 F plus. After the tint, I hardly ever use Max A/C because Auto 3 does it all by itself. During the cooler seasons, I use Auto 1 or 2 and like how they function.

As far as the car goes, while in stop and go traffic.....the battery chiller will be able to maintain battery temp even in 85 F weather. The A/C compressor cools the battery, electronics and motors as well as the passenger compartment. The battery and EV drivetrain have priority so the car will limit cooling to the passenger compartment if needed. I doubt you encountered that scenario though. My guess is that your windows might not be tinted and the thermal gain is something you don't experience that often in your region so it felt uncomfortable.

As for what you should do next time.....I think you might try the higher Auto setting and that should do the trick. If that doesn't make it more comfortable then try manually selecting a higher fan speed and possibly turning on the recirculation so you are not cooling outside air. Then when the temp is comfortable, put it back to Auto again. I use that method quite a bit vs Max A/C because Max A/C sometimes cools down the cabin too much and then when I go back to Auto, the heater comes on. Then I have to go back to the climate control screen and turn off e heat etc, etc. So, I find it easier to just leave the temp setting how I like it (73 F) and switch between Auto 3 or manual fan speed with the occasional Recirc enabled.

Hope these tips help.
 
Last edited:

Shayne

Well-Known Member
Joined
Aug 9, 2020
Threads
11
Messages
1,817
Reaction score
1,673
Location
Northern Ontario Canada
Vehicles
2021 MME4x Prem
Occupation
Retired
Country flag
Query whether the battery cooling systems make use of it in some way, but HVAC is based on the settings the driver sets the cooling or heating to.
One would think there are interior battery sensors for their temp and the one on the display screen is not used other than for us to see. Hence the accurate some have noted here.

I can see @djett concern as I may have had the same. It is my ice upbringing and the engine heats up when sitting idling with less air going through the fan. Whole different tech here to get use of.
 
OP
OP

djett

Well-Known Member
Joined
Nov 5, 2020
Threads
15
Messages
124
Reaction score
179
Location
CT
Vehicles
Mach E Premium AWD
Country flag
Also consider the direction of the sun relative to your driver side window. If the sun was baking your steering wheel until you left the Mass Pike and headed in a new direction or trees/buildings obscured the sun's radiant heat, then this will make a marked difference on how hot it feels for you as the driver.

A smaller thing, but your stress/anxiety also went down when you changed roads, and that will help you cool down and be more comfortable.
f2cdcece243cf45545d7cdccb12228f7cc095142051c5ac900faab72d5c0eb3c.jpg
 

Chuck

Well-Known Member
First Name
Chuck
Joined
May 13, 2021
Threads
35
Messages
722
Reaction score
1,022
Location
SoCal
Vehicles
Mustang Mach E 2021
Country flag
Came back from Boston yesterday and traffic was worse than usual on the Mass Pike due to impending doom (aka Hurricane Henri). Traffic was stop & go for about 15 miles. It was relatively hot (85F) and very humid. I was watching the external temperature on the screen creep up. It got up to 100F. It was not 100F outside. I also noticed the interior of the car was getting warmer. At the next exit I jumped off the Mass Pike and took a different route home. As soon as I was out of stop & go traffic and back to normal highway speeds the external temp came back down to the actual outside temperature and the cabin cooled back to normal.

Are there any tips I should know if I'm in this situation again - and not able to exit stage left?
I find it funny that anyone thinks that 85 is "heat."

 

 
Top