Hi PriusChat, I bought my 2012 Prius about 6 months ago to replace my stolen 2006 Corolla. I live in Toronto, Ontario Canada and yesterday was the coldest day thus far in 2015. I finally got to see how well the Prius performs on one of the coldest days. It was -21 degrees celsius (-5.8 fahrenheit). Last year at this time there was an ice storm and was even colder at -32 degrees celsius (-25.6 fahrenheit). I drive 100 miles round trip to work (mostly on the highway), so the car has lots of time to warm up. My problem is that I was pretty disappointed with the performance of the Prius defogger. I tried the defogger with legs setting with the auto settting and then increased the temperature. I later tried the front defogger button. My fan speed went to max. No matter what I did, I couldn't defog the top 25% of my front windshield. My side windows were 50% fogged up and my rear windows were 85% fogged up. Long story short, the defogger worked but sort of sucked. Can anyone else comment on the Prius defogger? I also found the heater not as great as well.
Did you have the AC on as well? Blowing hot air will clear the part of the window it is hitting, but AC will also dehumidify the air, clearing the rest of the glass.
I fiddled with all the controls to get the defogger to work better. I don't remember what I did with the AC. I will try keeping the AC enabled on my next trip.
i've never had any problem defogging, but the coldest here is usually only a few below 0 degrees f. do you feel like the damper is allowing full flow to the windshield vents?
Mine works just fine in Edmonton. I leave it on "auto" and press the front defog button. The rear defog is the electric heater traces on the hatch glass and they work fine as well. Make sure the system is taking in outside air, not recirculating inside air. On auto it does this automatically. Also make sure you don't have wet carpets. If that's a problem get a set of "Weathertech" carpet protectors, the "laser measured" ones.
I concur, the heater is fine so far, but it's not so easy to keep the windshield clear, particularly in cold and humid weather. I think it helps to close-off some of the air-vents you aren't using. I had my rear-defogger in for service, because I didn't think it was working properly, but they said it checked out fine. These things are normally very power-hungry, therefore it's a bit under-rated to save power.
I don't think the AC compressor will actually come on when outside temp is below freezing even if the light shows on. Something to do with compressor/coolant not working below freezing ambient. AC on during defrost/defog is usually for humid conditions, not extreme cold. I think our OPs problem is that it's just too friggin cold for that little 1.8L engine to put out any heat!
On my 2013, AC comes on automatically once you press front defogger. If I turn AC off and try to defog, it's almost useless. Make sure AC is on.
The only time I had issues with the front defroster is when it was -40 or when I have a full load of passengers. I had the same problems you had in that it couldn't clear the frost (yeah it iced up inside) at the top of the windshield at -40. In the scenario with the full load of passengers, it wasn't too bad but the rear side windows never cleared but the windshield is ok and so was half of the front side windows. This was at warmer, humid temperatures (4°C and raining outside). Make sure your A/C button is on if you're in manual mode (If you're in AUTO, just leave the A/C light on as it'll cycle on/off as necessary). A/C dehumidifies the air, blowing dry air. I use the front defogger and of course it'll go full blast in AUTO mode because it wants to clear it as fast as possible. Oh and I would check the cabin air filter to make sure it isn't dirty or clogged up. That'll restrict air flow, reducing the performance of the climate control. I found the heater adequate. It'll start pumping out warm air in less than 7 mins and a warm-ish cabin in less than 10 mins. I also take it you're not in Toronto, cause -32°C is basically an all time record low at Pearson. Either it's a wind chill you remember or you're commuting from cottage country.
Yes but the fan is clearly not strong enough to reach the top of the large windshield. It's a catch-22 though. A more thermally efficient ICE means less available heat for the cabin. Toyota would be wise to include active grille shutters to vary the cooling need to improve cold air performance (despite your stance on it) or find a way to supplement the heater (the Gen 2 had a PTC heater IIRC).
That's right. It's needed not only for heat, but also to minimize unnecessary aero drag. It's strange Toyota doesn't bother to include it, when even cars as inexpensive as the Nissan Note have active grill shutters.
I've been wondering about this too. I think they don't have grill shutters for a few reasons, one being it could be added cost/complexity (notice the complaints about the subpar interior even on higher trims?), but I think the bigger reason is that Toyota thinks people are morons, and will forget to open them back up when it gets warm. And if they damage their engine because they forgot to open the grill, then some lawyer may throw a lawsuit in.
Exactly. And a well-designed coolant thermostat would accomplish that job anyway. Using shutters is just a more expensive way of doing the same job.
The active part means they automatically open and close. No one would trust the average person to manually open them. The don't replace the thermostat. The airflow through the engine bay can cool the engine even when the thermostat is closed.
My car has been doing fine lately. Started right up in -18F Thursday morning. Heat came on quick during my 10 mile drive to work. I had it blasting most of the way. The car doesn't seem to be as well insulated as others I have owned. No worries though!
Because when Toyota designed this, it was back in the mid-2000s and this car was launched in May 2009. No one had active grille shutters back then. In fact, when the Prius was launched, PCS/DRCC/LKA/LED headlights were unheard of in its price range or class. The Prius was ahead of its time in other areas.
I drive on the highway for one hour heading north from Toronto in the cold and early in the morning. Yesterday was -21deg. My other forum post was my wiper fluid getting frozen. My comment is that the Prius defogger just doesn't perform as well as all the other ICE cars I've driven. I've driven 4 other cars the same route in the winter that did better defogging. All of ICE cars I drove could defog the front side windows completely on the highway. My Prius could only defog half of the front side windows at highway speeds.
