2020 Leaf ... adjust air temp?

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SBCLeaf

Well-known member
Joined
Oct 25, 2020
Messages
84
Today was the first hot day since I bought the Leaf, and I discovered that the temperature of the A/C output cannot be adjusted. In every car I've ever owned for the last 30 years you just turn on the A/C and adjust the temperature knob to where you like. The air blows out of the vents at that temperature. The Leaf doesn't do that. Whether the temp is set to 60 or 90 the air comes out the same ice cold temperature.

I want to be clear I'm not talking about AUTO climate control. I'm talking about adjusting the temperature of the air coming out of the vents, not the cabin temperature. Meaning in fully manual mode the temperature knob has no effect.

Is that "normal" for the Leaf, or is something wrong with my car?
 
cwerdna said:
What if you turn on the heater while adjusting the temp?

That seemed to work, but I do not know how the systems work internally. My fear is that they are battling each other to produce the desired temperature (and wasting a lot of electrons). For example, if I push the A/C button and set the temp to 77, I would expect that the compressor would only run for a short bit to get the evaporator coil down to around 77, and then repeat as necessary. With the heat and A/C on I'm afraid that the car might actually be wasting electricity actively heating to counter the cold evaporator coil.

Is there a way to test if that's happening?
 
Unfortunately, if you run and heat and A/C at once in the Leaf, you are running both the heatpump (A/C) and PTC resistance heater (heat). This uses a lot of power.

However, I question the premise here: in most cars, when you select A/C, the compressor cycles according to a thermostat setting. The thermostat simply turns the compressor on and off - it doesn't moderate the A/C airstream temp. Many cars have "A/C Max" but that is just A/C with recirculate, which makes the air colder because it's being recirculated through the system. There are probably a few systems out there that can change the temp of the air stream from the vents, but they aren't the norm.

Now, a suggestion: when you want less cold air blowing on you, do two things: open the Recirculate valve so you are getting all fresh air, and select a vent setting that isn't blowing the air right on you, like Floor + Defrost. You can also re-aim the vent louver so the stream is more indirect. Mid-level vents only selected, fresh air, and the louvers aimed mostly away from you should fix the problem.
 
On lower fan speeds, the cold air mixes with more of the ambient air before reaching you so you don't get that icy blast. I find the "auto" setting works pretty well and only boosts the fan speed when the cabin needs to cool in a hurry or there's a big heat load to overcome. In those more direct airflow is usually welcome. If not I just aim the vents away from me or take it out of auto mode and adjust the fan manually.
 
SBCLeaf said:
Today was the first hot day since I bought the Leaf, and I discovered that the temperature of the A/C output cannot be adjusted. In every car I've ever owned for the last 30 years you just turn on the A/C and adjust the temperature knob to where you like. The air blows out of the vents at that temperature. The Leaf doesn't do that. Whether the temp is set to 60 or 90 the air comes out the same ice cold temperature.

I want to be clear I'm not talking about AUTO climate control. I'm talking about adjusting the temperature of the air coming out of the vents, not the cabin temperature. Meaning in fully manual mode the temperature knob has no effect.

Is that "normal" for the Leaf, or is something wrong with my car?
All A/C's for cars just cycle the compressor on and off to vary the cool, same for electric heat, just cycles it from off to 100% and the longer it's off the colder or warmer the air will be. Now with heat, some heaters might have a high and low switch where the high setting uses a different coil and therefore can give more heat but if it has a thermostat it will be cycling the coil off to give less heat. Now for A/C it's possible for an electric compressor to use unloaders to vary the maximum cool or electric scroll compressors can also lower the maximum cool, resulting in warmer discharge air temp but they still turn off and on the compressor to raise the discharge temp. I doubt the electric compressor in our Leafs do anything other than cycle the 100% compressor off and on to raise the discharge temp but I could be wrong.
 
jjeff said:
All A/C's for cars just cycle the compressor on and off to vary the cool, same for electric heat, just cycles it from off to 100% and the longer it's off the colder or warmer the air will be.

That's what I was trying to say had been my experience in the past. The Leaf does not appear to operate that way. If the A/C is activated it's on 100% no matter what the temperature knob is set to. You can verify by measuring the temperature of the air with the knob turned to 60 and turned to 90 (or 70 or 80), the output temperature doesn't change.

I do not want the fan on low. I want the fan speed constant however I set it and the temperature of the output to be regulated by the setting of the temperature adjustment knob. It's how every car I've ever driven until the Leaf works. It seems strange that they'd take a car whose whole point is efficiency and then make the climate controls work in the most inefficient way possible.
 
LeftieBiker said:
Good point about lower fan speeds. I was assuming that he already does that.

No. I do not want to use fan speed to regulate temperature. I want the car to cycle the compressor to regulate temperature. I want the fan speed to be whatever I want it to be and stay there. This is not an unusual expectation. Every car that I've ever used in 30 years of driving, including dozens of rentals and a half dozen of my own cars works this way.

Cycling the fan speed to regulate temperature and just running the compressor at 100% is the most inefficient possible way to regulate cabin temperature.

LeftieBiker said:
Now, a suggestion: when you want less cold air blowing on you, do two things: open the Recirculate valve so you are getting all fresh air, and select a vent setting that isn't blowing the air right on you, like Floor + Defrost. You can also re-aim the vent louver so the stream is more indirect. Mid-level vents only selected, fresh air, and the louvers aimed mostly away from you should fix the problem.

I find it almost impossible to believe this is how people are expected to regulate the cabin air temperature in the Leaf. First, I do not want outside air under any circumstances as I'm driving on a highway full of Diesel trucks. Second, I do not want to point the vents toward me when I get cold and away when I get hot. I just want the temperature knob to control the temperature of the A/C. This is how every car on the planet works (except the Leaf, apparently).
 
SBCLeaf said:
Today was the first hot day since I bought the Leaf, and I discovered that the temperature of the A/C output cannot be adjusted. In every car I've ever owned for the last 30 years you just turn on the A/C and adjust the temperature knob to where you like. The air blows out of the vents at that temperature. The Leaf doesn't do that. Whether the temp is set to 60 or 90 the air comes out the same ice cold temperature.

I want to be clear I'm not talking about AUTO climate control. I'm talking about adjusting the temperature of the air coming out of the vents, not the cabin temperature. Meaning in fully manual mode the temperature knob has no effect.

Is that "normal" for the Leaf, or is something wrong with my car?

Been normal for me since 2013 and 4 different versions. "auto" works by adjusting fan speed to match thermal gain. Doesn't change air temperature coming from the vents either.
 
SBCLeaf said:
cwerdna said:
What if you turn on the heater while adjusting the temp?

That seemed to work, but I do not know how the systems work internally. My fear is that they are battling each other to produce the desired temperature (and wasting a lot of electrons). For example, if I push the A/C button and set the temp to 77, I would expect that the compressor would only run for a short bit to get the evaporator coil down to around 77, and then repeat as necessary. With the heat and A/C on I'm afraid that the car might actually be wasting electricity actively heating to counter the cold evaporator coil.

Is there a way to test if that's happening?

LEAF Spy and you are using way more power than you need to. Lower fan speed. As a joke, my A/C is set to 88º (something any BTTF fan would know)

The problem with the temperature setting is the location the temperature is sampled from. You say its cold because you are siting 18 inches from the vent. Its no different than getting the lucky seat at the restaurant in July (you know the one; its the booth where everyone is still wearing their coats) But the sensor only knows how cold/hot it is, not you and therein lies the problem. Using a single sensor for heat and A/C is by design, a half assed solution. So adjust fan speed accordingly or use automatic (which I hate BTW)
 
DaveinOlyWA said:
LEAF Spy and you are using way more power than you need to. Lower fan speed. As a joke, my A/C is set to 88º (something any BTTF fan would know)

The problem with the temperature setting is the location the temperature is sampled from. You say its cold because you are siting 18 inches from the vent. Its no different than getting the lucky seat at the restaurant in July (you know the one; its the booth where everyone is still wearing their coats) But the sensor only knows how cold/hot it is, not you and therein lies the problem. Using a single sensor for heat and A/C is by design, a half assed solution. So adjust fan speed accordingly or use automatic (which I hate BTW)

The point is I do not want to lower fan speed. The circulation fan is also filtering the air. I do not want less filtration because I'm cold/hot. Or when there's five people packed in the car I want more ventilation that when there's just me. That shouldn't mean I have to lose control of the temperature.

I say it's cold because the cabin gets too cold when the fan is on high no matter what temperature is set and no matter where the vents are aimed or which vents are active.

I can't find on LeafSpy where to see the real-time current draw. Which screen is it on?
 
I confirmed with LeafSpy that the heater battles the A/C when you have both on.

Perhaps I should approach this from a different way: What is the function of the temperature knob when the system is not in AUTO?

The manual isn't specific, but suggests operating this way should work as I expect:

dm-604GU2.png
 
SBCLeaf said:
DaveinOlyWA said:
LEAF Spy and you are using way more power than you need to. Lower fan speed. As a joke, my A/C is set to 88º (something any BTTF fan would know)

The problem with the temperature setting is the location the temperature is sampled from. You say its cold because you are siting 18 inches from the vent. Its no different than getting the lucky seat at the restaurant in July (you know the one; its the booth where everyone is still wearing their coats) But the sensor only knows how cold/hot it is, not you and therein lies the problem. Using a single sensor for heat and A/C is by design, a half assed solution. So adjust fan speed accordingly or use automatic (which I hate BTW)

The point is I do not want to lower fan speed. The circulation fan is also filtering the air. I do not want less filtration because I'm cold/hot. Or when there's five people packed in the car I want more ventilation that when there's just me. That shouldn't mean I have to lose control of the temperature.

I say it's cold because the cabin gets too cold when the fan is on high no matter what temperature is set and no matter where the vents are aimed or which vents are active.

I can't find on LeafSpy where to see the real-time current draw. Which screen is it on?

Its the main screen with the bar charts. Toggle the chart to show current power usage. Be default is on the GID, SOH, etc. (which is COMPLETELY USELESS unless you like watching molasses run in January)

You should see motor power
ACC power
Heat
A/C

I am currently doing experiments playing with A/C, heat and evaluating defogging effectiness with vent closed, airflow to feet.

A/C and heat run independently of each other and your suspicion is correct; they will fight each other. Your only real option after fan speed is adjusting vents. This worked for me. I would blow directly on me initially then aim the vents against the glass on the door.

I also toggle A/C on and off frequently. I am a adamant "vent closed" person and yes, it makes a HUGE difference as to how well I can smell other's exhaust.

For LEAF Spy screenshots

https://daveinolywa.blogspot.com/2021/01/december-2020-drive-report-hope-for-new.html
 
Based on this:

dm-V8ZFC8.png


I thought I'd found a way to accomplish what I want, but it appears the system has "outsmarted" me. You can't have the A/C on in AUTO mode if the outside temperature is below the set temperature. It doesn't matter if your cabin is 85 degrees from sitting in the sun with 4 people inside. If it's 68 outside and you set your temperature to 72 and press AUTO it will disengage the A/C anyway. If you press A/C it disengages AUTO.

I'm still at a loss for words that the temperature control knob doesn't control anything.
 
In my experience, most (or all?) ICE cars actually blend warm air from the heater core with the AC output to modulate the AC temp. So the Leaf is no different except that it doesn't an unlimited 'free' source of heat to mix with the cold air output. The AC compressor clutch is used to maintain a specified refrigerant pressure in the AC system since the pressure is critical for the evaporation to occur properly.

https://www.2carpros.com/articles/how-a-car-air-conditioner-works
 
goldbrick said:
In my experience, most (or all?) ICE cars actually blend warm air from the heater core with the AC output to modulate the AC temp. So the Leaf is no different except that it doesn't an unlimited 'free' source of heat to mix with the cold air output. The AC compressor clutch is used to maintain a specified refrigerant pressure in the AC system since the pressure is critical for the evaporation to occur properly.

https://www.2carpros.com/articles/how-a-car-air-conditioner-works

I've never heard of such a thing. In every car I've ever owned you can hear the A/C compressor kick on and off periodically to regulate temperature of the evaporator coils. The colder the setting the longer it's on and vice versa. I've never seen or heard of a car that just blasts the A/C compressor full-bore all the time and uses the heater core to modulate the output.
 
SBCLeaf said:
That's what I was trying to say had been my experience in the past. The Leaf does not appear to operate that way. If the A/C is activated it's on 100% no matter what the temperature knob is set to. You can verify by measuring the temperature of the air with the knob turned to 60 and turned to 90 (or 70 or 80), the output temperature doesn't change.

I do not want the fan on low. I want the fan speed constant however I set it and the temperature of the output to be regulated by the setting of the temperature adjustment knob. It's how every car I've ever driven until the Leaf works. It seems strange that they'd take a car whose whole point is efficiency and then make the climate controls work in the most inefficient way possible.

Perhaps there's a problem with your car, because my experience with the LEAF electric AC is the exact opposite. If I monitor the energy consumption I can clearly see it decline from a high level initially when starting in a hot car, and gradually dropping as the internal temperature reaches the set point. After that the consumption stays at whatever level is needed to compensate for any heat and/or solar gain. It seems to me LEAF varies the compressor RPM as opposed to ICE vehicles with mechanical compressors that are either ON or OFF. The service manual confirms this (range is 0-9000 rpm). It's one of the advantages of an electric compressor.

This A/C uses various sensors to detect temperature changes in the interior caused by factors such as changes in ambient temperature and sunload. When the desired temperature is set, the discharge air temperature, discharge air flow, and inlet/outlet changes are controlled automatically to maintain a constant interior temperature at all times.

There's also an "air mix door", like many (most?) other cars that blends cabin air to achieve a desired vent output temperature.

The rotational movement of the motor is transmitted via the rod and lever to the air mix doors (upper air mix
door, lower air mix door), changing the discharge air temperature.
 
SBCLeaf said:
Based on this:

dm-V8ZFC8.png


I thought I'd found a way to accomplish what I want, but it appears the system has "outsmarted" me. You can't have the A/C on in AUTO mode if the outside temperature is below the set temperature. It doesn't matter if your cabin is 85 degrees from sitting in the sun with 4 people inside. If it's 68 outside and you set your temperature to 72 and press AUTO it will disengage the A/C anyway. If you press A/C it disengages AUTO.

I'm still at a loss for words that the temperature control knob doesn't control anything.

I found that to be not true. You could experiment with setting the thermostat to near ambient but I found that to very undesirable as the "AC smell" is immediate when the evaporator is turned off and takes too long to cycle back on. I am not quite sure I understand this as low AC demand shows power draw only about ONE THIRD TO ONE FOURTH of the time?
 
Nubo said:
Perhaps there's a problem with your car, because my experience with the LEAF electric AC is the exact opposite. If I monitor the energy consumption I can clearly see it decline from a high level initially when starting in a hot car, and gradually dropping as the internal temperature reaches the set point.

I'm not as concerned with the energy consumption as I am with the temperature. The air coming out of the vents is 40 - 42°F whether the temperature control is set to 60 or 90. No adjustment of the knob has any effect on the temperature of the output. Even with the cabin at 65° in the morning, the A/C will still output 40° with the temperature set to 90.
 
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