Understanding air conditioner compressor operation

Maquis

Well-Known Member
First Name
Dave
Joined
Dec 21, 2020
Threads
30
Messages
4,403
Reaction score
6,093
Location
Illinois
Vehicles
2021 Mach E4X, 2023 Lightning Lariat ER
Country flag
Here's the setup:
On a drive yesterday, outside temp is 73F with light drizzle. It would be a perfect day to be outside other than the light rainfall. I set out with climate control on, AC off, and temp set to "Low". I expected this to simply run the fan and pull in outside air.
Within minutes, I'm freezing in the car. Up the temp to 75, then 78. Still very cold air coming out of the vents. I checked the settings to be sure the AC was still set to off.

Had it not been for the rain, I would have simply turned off climate control completely and opened the windows.

The only thing I see in the manual is this:
Note: Under certain conditions, the air
conditioning compressor could continue to
operate after you switch air conditioning off.
Not helpful! No description of those "certain conditions".

Any insights, thoughts, other experiences?

Thanks!
Sponsored

 

ZuleMME

Well-Known Member
First Name
Zule
Joined
Apr 23, 2021
Threads
10
Messages
1,020
Reaction score
1,481
Location
Denver, CO
Vehicles
21' Job1 P4X MME, 22' MYP
Occupation
Implementation Engineer
Country flag
When running the defroster the A/C is a required element and it runs to remove the humidity from the air. Normal operation.
 

JamieGeek

Well-Known Member
Joined
Dec 29, 2019
Threads
82
Messages
3,556
Reaction score
6,746
Location
Southeastern Michigan
Website
spareelectrons.wordpress.com
Vehicles
Mach-E, old: Bolt, C-Max Energi, Focus Electric
Country flag
In those conditions I simply leave the temp as is and make sure A/C & E-Heat are both off. That seems to do the trick--no need to set to "low" (it is possible the "low" setting also forces the A/C on given that you're telling the car to be a fridge).
 
OP
OP
Maquis

Maquis

Well-Known Member
First Name
Dave
Joined
Dec 21, 2020
Threads
30
Messages
4,403
Reaction score
6,093
Location
Illinois
Vehicles
2021 Mach E4X, 2023 Lightning Lariat ER
Country flag
When running the defroster the A/C is a required element and it runs to remove the humidity from the air. Normal operation.
Defroster was not on.

What you say is true - AC runs when calling for defrost when above freezing. That's been common in most all cars for years. However, I would say it's not always required. I'd like to have the option to run the compressor only when I want to. The best set of climate controls I've ever owned was in my 1988 F250. Everything was controllable by me.
 
OP
OP
Maquis

Maquis

Well-Known Member
First Name
Dave
Joined
Dec 21, 2020
Threads
30
Messages
4,403
Reaction score
6,093
Location
Illinois
Vehicles
2021 Mach E4X, 2023 Lightning Lariat ER
Country flag
In those conditions I simply leave the temp as is and make sure A/C & E-Heat are both off. That seems to do the trick--no need to set to "low" (it is possible the "low" setting also forces the A/C on given that you're telling the car to be a fridge).
I thought that might be the case, but expected it to turn off once I set the temperature above outside ambient.
 


benk016

Well-Known Member
First Name
Ben
Joined
Nov 12, 2020
Threads
37
Messages
3,013
Reaction score
4,671
Location
Tulsa, Oklahoma
Vehicles
2021 Mustang Mach-E GT
Country flag
The compressor will also run to cool the battery if needed as well. Possible a software bug is letting the inside AC stay on if the compressor is on to cool the battery?
 

Murse-In-Airy

Well-Known Member
First Name
Rod
Joined
Mar 5, 2021
Threads
74
Messages
3,389
Reaction score
7,618
Location
Chaumont, NY
Vehicles
Mach-E ER AWD
Occupation
Nurse
Country flag
“Certain conditions” may also include high humidity as air conditioning is also dehumidifying. Perhaps the car didn’t want your windows to fog so it left the dehumidifier on. Then when you set the temperature to something something Kelvin it said “OK, here we go!”
 

BMT1071

Well-Known Member
First Name
Mike
Joined
Mar 21, 2021
Threads
61
Messages
3,076
Reaction score
4,223
Location
Glendale, AZ
Vehicles
21 MME SR RWD, 23 MME GTPE
Occupation
Machine Control Specialist
Country flag
The compressor will also run to cool the battery if needed as well. Possible a software bug is letting the inside AC stay on if the compressor is on to cool the battery?
Seems unlikely the battery would need refrigeration cooling in the ambient temp OP listed. But hey, you never know. ??
Sponsored

 
 




Top