Fan only cooling

[JCA]

So this ties in with an idea of mine. If you have ever had mildew build up in your air conditioner, and the resulting odor each time you start your car, you never want it to happen again. It is difficult and potentially expensive to remove the mildew.

So on my last car (Prius) what I started doing during the summer was turning off AC when I was about a mile from the house and then turning on the fan full blast. Felt fine at first of course because the coils were still cold, and if I timed it right by the time the cabin started getting uncomfortably warm I had arrived at home. I eventually thought of going online to see if anyone else had tried this, and from what I read the concept itself is a sound one, however they said running only a couple of minutes like I was doing would likely have little to no effect, you would have to run the fan much longer. I knew I couldn't survive running it any longer so I just kept up my "last mile" method. After thirteen years of southern humidity there was no mildew smell, although I have no idea if that had anything to do with me running fan only for the last mile.

So now I have a Clarity, and guess what? I realized that before getting out of the car during the summer I can set climate to fan only. Then exit the car, and using the fob (or app) start climate control, which will run for 30 minutes then shut off. Seems like it would use little in the way of battery charge, basically none if I am plugged in, and maybe it will help keep the mildew gremlins away. Only thing is I would have no way of knowing if it is effective, other than no news is good news, but it doesn't seem like it would hurt anything.

I don't believe the remote preconditioning uses the last settings you had; I'm pretty sure it targets something like 75 degrees and turns on the heat or AC itself depending on whether the interior is over or under that. That's been my experience with it also. Otherwise it would be a useless waste for many of us (much of the year it's cool enough for heat or just fan in the morning, and hot enough for AC in the afternoon).

 

[KentuckyKen]

So this ties in with an idea of mine. If you have ever had mildew build up in your air conditioner, and the resulting odor each time you start your car, you never want it to happen again. It is difficult and potentially expensive to remove the mildew.

So on my last car (Prius) what I started doing during the summer was turning off AC when I was about a mile from the house and then turning on the fan full blast. Felt fine at first of course because the coils were still cold, and if I timed it right by the time the cabin started getting uncomfortably warm I had arrived at home. I eventually thought of going online to see if anyone else had tried this, and from what I read the concept itself is a sound one, however they said running only a couple of minutes like I was doing would likely have little to no effect, you would have to run the fan much longer. I knew I couldn't survive running it any longer so I just kept up my "last mile" method. After thirteen years of southern humidity there was no mildew smell, although I have no idea if that had anything to do with me running fan only for the last mile.

So now I have a Clarity, and guess what? I realized that before getting out of the car during the summer I can set climate to fan only. Then exit the car, and using the fob (or app) start climate control, which will run for 30 minutes then shut off. Seems like it would use little in the way of battery charge, basically none if I am plugged in, and maybe it will help keep the mildew gremlins away. Only thing is I would have no way of knowing if it is effective, other than no news is good news, but it doesn't seem like it would hurt anything.

@2002, that’s a great idea that I hadn’t heard of before, but that makes sense. I sometimes get that smell briefly at the start of AC season mostly. I will try your suggestion. It’s easy to do and and won’t cost any comfort or kWs. In fact, it will be infinitesimally cheaper which appeals to my lingering old hyper-mile attitude. Thanks for the tip.

However, I don’t think we will be able to do it with the key fob. This is because preconditioning does not allow for any user adjustments. It uses a range of outside and inside temperatures to calculate whether to use heat or AC and even whether to come on at all.
Attached is the explanation which I think was first shared by @jdonalds.

 

[Geor99]

So this ties in with an idea of mine. If you have ever had mildew build up in your air conditioner, and the resulting odor each time you start your car, you never want it to happen again. It is difficult and potentially expensive to remove the mildew.

So on my last car (Prius) what I started doing during the summer was turning off AC when I was about a mile from the house and then turning on the fan full blast. Felt fine at first of course because the coils were still cold, and if I timed it right by the time the cabin started getting uncomfortably warm I had arrived at home. I eventually thought of going online to see if anyone else had tried this, and from what I read the concept itself is a sound one, however they said running only a couple of minutes like I was doing would likely have little to no effect, you would have to run the fan much longer. I knew I couldn't survive running it any longer so I just kept up my "last mile" method. After thirteen years of southern humidity there was no mildew smell, although I have no idea if that had anything to do with me running fan only for the last mile.

So now I have a Clarity, and guess what? I realized that before getting out of the car during the summer I can set climate to fan only. Then exit the car, and using the fob (or app) start climate control, which will run for 30 minutes then shut off. Seems like it would use little in the way of battery charge, basically none if I am plugged in, and maybe it will help keep the mildew gremlins away. Only thing is I would have no way of knowing if it is effective, other than no news is good news, but it doesn't seem like it would hurt anything.

Just a thought. After you get home, you could plug in and run your heater on full blast for 3-5 minutes. This would completly dry out any moisture, if you have problems with it.

It would also potentially kill any mildew.

 

[Pushmi-Pullyu]

I get tremendous wind buffet from opening the rear windows at speed. Front windows OK, but I wonder how much drag we are creating.

Probably a significant amount of drag. "Myth Busters" did a comparison of running a gasmobile with windows up and A/C on vs. running with A/C off and windows down. MPG was worse with the latter case. Of course that was likely with front windows down vs. rear windows down, but common sense suggests that's not gonna make all that much difference. The point is that rolling windows down creates aero turbulence, which increases drag enough to make a real impact.

However, that comparison may not apply to running a PHEV under battery power. Use of A/C and cabin heating impacts EV range more than gasmobile MPG. EVs are designed to be more energy-efficient than gasmobiles, but the flip side of that is that they have less energy to waste on heating and cooling.

Bottom line: We need to see a comparison similar to what "Myth Busters" did, but using either a BEV or a PHEV using EV mode only.

​

 

[JustAnotherPoorDriver]

However, I don’t think we will be able to do it with the key fob. This is because preconditioning does not allow for any user adjustments. It uses a range of outside and inside temperatures to calculate whether to use heat or AC and even whether to come on at all.
Attached is the explanation which I think was first shared by @jdonalds.

Ken,

Not sure this is true: I came into work this am in the cold, and had the fan only setting on (manually selected AC off). When I left today, I preconditioned the car (it was ~98 degrees when it started, ~80 outside) and the temp ended up going up--the fan ran, but the AC compressor never came on. The AC works fine when selected. It could be that there's something wrong with the car, but another possibility is that the AC recalled that I manually turned off the compressor and kept my setting. I'll try it next week and work and try to figure it out.


p.s. I've been doing what 2002 suggested for years in my Subaru.
p.p.s. Pushmi - The heat is basically free in a ICE vehicle (waste heat) but we create it using resistance, which is expensive. ACs (and heat pumps) move existing heat, and are more efficient--the AC in our car should be identical to any electrically driven AC (vs belt driven compressor) in an ICE car, and should be relatively efficient. I'd expect the mythbuster's conclusion to hold still.

 

[KentuckyKen]

Ken,

Not sure this is true: I came into work this am in the cold, and had the fan only setting on (manually selected AC off). When I left today, I preconditioned the car (it was ~98 degrees when it started, ~80 outside) and the temp ended up going up--the fan ran, but the AC compressor never came on. The AC works fine when selected. It could be that there's something wrong with the car, but another possibility is that the AC recalled that I manually turned off the compressor and kept my setting. I'll try it next week and work and try to figure it out.


p.s. I've been doing what 2002 suggested for years in my Subaru.
p.p.s. Pushmi - The heat is basically free in a ICE vehicle (waste heat) but we create it using resistance, which is expensive. ACs (and heat pumps) move existing heat, and are more efficient--the AC in our car should be identical to any electrically driven AC (vs belt driven compressor) in an ICE car, and should be relatively efficient. I'd expect the mythbuster's conclusion to hold still.

Thanks for the observation. We need all the data points we can get to be able to reverse engineer this car.
That’s a puzzler since this diagram and text (first posted by @jdaniels, I think) seemed to indicate that it worked on a set of inside and outside temps automatically and wasn’t user selectable. Perhaps there are exceptions in the algorithm or some set of conditions that we haven’t got info on. Keep noticing what it’s doing and keep us updated.
Attached is a repost of that diagram:

 

[JCA]

Ken,

Not sure this is true: I came into work this am in the cold, and had the fan only setting on (manually selected AC off). When I left today, I preconditioned the car (it was ~98 degrees when it started, ~80 outside) and the temp ended up going up--the fan ran, but the AC compressor never came on. The AC works fine when selected. It could be that there's something wrong with the car, but another possibility is that the AC recalled that I manually turned off the compressor and kept my setting. I'll try it next week and work and try to figure it out.


p.s. I've been doing what 2002 suggested for years in my Subaru.

I will try to remember tomorrow to make sure the AC is off when I get to work to get another data point; we're having 100+ degree weather so it's easy to tell if the preconditioning cools it down in the afternoon! Most spring days it's quite cool in the morning, so the AC is off, and warm enough to need it in the afternoon, and I'm very certain it's preconditioned fine on those days. I don't use the auto button, and turn the AC on/off manually, because while I'm fine to cool to 70 thermostatically, I *never* want to be blasted with heat in my car if it's in the 50s or 60s already -- especially not expensive electric heat.

The preconditioning stops when you unlock or open the door (not sure which) so it can be hard to tell if it was operating, and when you start the car I believe the climate control settings are back where you left them, so you'd have to turn on the AC at that point if it had been off when you left it, even if it had been used for preconditioning.

I've also had the car seem to get the signal or not started it soon enough and still be very hot inside when I got in (even when I'd used AC in the morning). It feels like under 5 minutes (the time to walk to my car) doesn't help much; turning it on 15 minutes before I leave results in a nice cool car when I get in. It takes the a couple minutes to get the signal and start up the system, and it takes the system several minutes to really cool and start making any appreciable difference when all the materials inside have been baking for hours.

From outside my car, the AC running is louder than the engine idling.

 

[insightman]

The preconditioning stops when you unlock or open the door (not sure which) so it can be hard to tell if it was operating...

In my experience, opening the driver's door shuts off preconditioning, but opening other doors does not.

 

[JCA]

So I stand corrected -- I made sure the AC was off today, and upon preconditioning the car was just as hot after 20 minutes. I even started preconditioning again while sitting in the car, and sure enough it was just blasting hot air. So apparently at least the AC control needs to be set right. Tomorrow I'll see what happens if the AC is on but the temp setting is high -- will it cool to the previous temperature setting, or to ~75?

I am a bit disappointed that it doesn't automatically turn on (or off) AC as needed, but at least now I know to turn/leave it on when I park in the morning.

 

[JustAnotherPoorDriver]

So I stand corrected -- I made sure the AC was off today, and upon preconditioning the car was just as hot after 20 minutes. I even started preconditioning again while sitting in the car, and sure enough it was just blasting hot air. So apparently at least the AC control needs to be set right. Tomorrow I'll see what happens if the AC is on but the temp setting is high -- will it cool to the previous temperature setting, or to ~75?

I am a bit disappointed that it doesn't automatically turn on (or off) AC as needed, but at least now I know to turn/leave it on when I park in the morning.

I'm disappointed too. I'm wondering if there's a way to tell the system that it's ok to turn the AC on when it starts preconditioning...without actually turning it on. It would be a pain to have to turn it on when I park it just so I can run it later.