AC was great in the summer but...

MichelleStone said: the heating system is somewhat lacking.

What heater??! It sucks. I turn the temperature up to 72 but it takes about 10 miles of driving for the inside to warm up. (Same with my wimpy AC. Half the time I get no air out of the upper vents. Half the time the AC will not get cold.)

One thing that I don't like is that when I set the heating to push air out the dash vents, the wind screen fogs up. I haven't been able to heat the cabin to the point where this doesn't happen to date. My trips are generally around 20 minutes or so and I'm usually driving in ECO mode.

Mine stays fogged up for 20 minutes! Doesn't matter what vent is on or off. Doesn't matter if the recycle is open or closed. Doesn't matter what drive mode I'm in. And it's REALLY bad when I get in the car in the morning, and the INSIDE of the window is all wet! I have to wipe it with a towel.

Worst heating/AC I've had in any car. Just another weird Prius thing... Toyota makes it ridiculously confusing.

 

I lived in the tropics (ie often 90+% humidity), but in the mountains, so it got chilly at night, often foggy - obviously nothing like where you were.

Have you been using the dehumidifying effect of A/C, the HEATER is much hotter than the A/C is cold. Try selecting A/C & SCREEN & HEAT - and the fog just peels off the screen - at least on cars which I've had in the past.

My last 3 cars, if you selected SCREEN, it would automatically select A/C. I haven't had fog in the PRIUS, so not sure if it selects it automatically too.

 

Turning up the temp does not increase it's output. Typically the ACC goes into recrirc when the delta is high .. this is normal, expected and beneficial. I never touch mine -- it's on 72. The AC should be on with pushing of the auto button. Best to leave the system to do it's job -- they work well if you don't try and think for them.

The only time I ever need the defrost is when it's raining or snowing and a high amount of moisture is introduced to the interior -- wet jackets .. etc.

 

Every time I press the "auto" button, the air flow defaults to the upper vents only. So it won't go to defrost, or floor, or anywhere else but the upper vents. And half the time I get very little (or no) airflow out of the upper vents... So the whole system is just confusing, in my opinion.

And how in the heck does the inside of the front windshield get dripping wet?

 

If the windshield is so wet it's because the car's interior humidity is way high! I suspect that your windows have been closed because of the cooler temperatures lately. So you will need the AC on with recirculate selected but being in ECO Mode, it will be too wimpy for a twenty minute trip. Instead you'll have to change climate from Eco to fast and ideally be in either normal or power mode for the car. Oh, and begin by selecting the screen defog button! You'll still be getting good mpg even if it's a couple of mpg lower, as you once proclaimed, it is still better than any other gas guzzler you ever had.

Don't let the weather beat your determination, help your car beat the weather. I have great faith in you!! Just believe in the car and believe in yourself too.

 

Really, how I do it?

I use Auto almost all of the time.

If the windows are fogging, I'll hit the front defrost button, and then it sends all energy into defogging.

Also, I try to minimize the amount of snow that comes into the interior on my shoes - snow melts, increasing humidity, and humidity in the interior is what fogs the windows.

 

It's very odd, because we rarely have any humidity here to speak of. I think when I leave the vents open overnight, regardless if it's summer or winter, I seem to get that wetness on the inside of the windscreen.

I never drive in the ECO mode. So I hope the HVAC is working at full maximum, however it still seems very wimpy sometimes. Takes quite a while to reach cold temperature, and it takes quite a while for the heater to warm up. Never had that problem in any other car. (Should've bought that Chevy Silverado!)

I stopped using the AUTO button, because when I wanted to change the vent selection or the fan speed, the auto button kicks off! So what good is it? I got tired of it always turning off, and having to turn it back on.
This Prius is overly complicated… Unnecessarily.

 

Or just leave it on auto, and don't mess with the vent selection or fan speed?

 

Sure it does. It increases the TOTAL output because it blows heated air longer......and when the heat is coming on mostly around your feet, a little perception can be worth a LOT.

And I gotta think about that second statement a bit. My initial reaction is: No it won't if you have your desired temp set way ABOVE ambient.
It absolutely would NOT be beneficial is there is an excess moisture problem in the cabin.

 

Actually, if outside air is humid, having AC in recirc to remove interior humidity is VERY helpful.

 

Well, I left Yosemite a couple hours before they closed the park. I went through Oakhurst on the 41.

 

Sometimes it's worth letting go of your hangups and following well meant advice. There is the auto button for the ACC and there's also a setting for the speed from the steering wheel buttons. ECO, NORMAL and FAST. You need that set to Fast! Also press the A/C button and select the windscreen defog button on the facia.

Remember this! You'll be tested on it at the end of your patience.

 

Damp or clogged pollen filter can cause more condensation too.

 

That seems like a logical conclusion but I've tried it over the years with a LOT of different cars and it just does NOT seem to work out like you think it would.

I think the difference is in the RELATIVE temperatures and humidities involved.

If the outside air is at 40F with a RH of 80 percent, just for example, once it comes through the heater core and goes up to 70F it will be fairly dry.......by comparison. And it will be expelling some of the inside moisture too.

 

Sam --- you need to read up on the ACC system. You don't understand the operation ... Also ..higher temps allow air to hold more moisture .... the moisture is still in the air.

The car knows the temps when you start the car -- You want a comfort temp (72) having the temps set to a higher or lower do nothing when typical comfort levels are desired.

The operation of ACC .. is not the same as a manual system.

 

Not going to have a flame war here are we ??
YOU need to refrain from making wild assumptions and telling others what they NEED to do.

I know perfectly well how it works.
As long as the moisture STAYS IN THE AIR and doesn't condense out, there is not a problem.

And your assertion seems to imply that the entire interior of the car reaches the set temperature all at the same time.
It does not. And perception is important. If my nose and ears are still COLD, it makes little difference what the temp is at my knees.

 

Water will condense out of moist air on a colder surface - on glass if it's below the dew point.

In the PRIUS Owners Manual, there is a section "Defogging the windshield" - I'd be trying that first - I expect TOYOTA would have researched it. There, it says:



In my case (not sure if it's different in other versions of the car), it turned the FAN to HIGH, turned A/C ON - but didn't change to OUTSIDE - I had to do that myself. Nor did it change the temperature setting - I have to turn it up myself, it seems. The ICE came on when I turned the temperature up, which I'd expect.

[The reason the A/C comes on - the A/C EVAPORATOR becomes cold - below the dew point and condenses the water in the air and drains it outside. The heater will attempt - albeit at the whim of the outside weather - to warm the glass.

As far as RECIRC or FRESH, it might depend on the moisture content of the air inside or out? Driving in FOG or other very humid situations in the tropics, I've found it better to select RECIRC in cars I've owned in the past. But with a lot of people breathing in the car, FRESH could be better. It could be something you could experiment with if TOYOTA's recommendation doesn't work for you. What works in your own climate - may not work in my climate.]

 

Try to quit messing with it. Leave it in auto and just drive it. The car will sort out the most effective way to heat or cool your car if you leave it in auto.

 

Not sure he'll get the message MrM. Prodigy reported he has been suspended from this forum.

 

Coast Cruiser was suspended? I find that shocking he didn't seem like the kind of person who would have a bannable offense. If I had to take bets on what regular poster would be facing the ban stick here I would've bet on myself over Coast Cruiser. Thanks for the info though.