Snow = no heat?

The snow accumulation will prevent entry of outside air. However it will not prevent the cabin heater from operating.

Note that the cabin heater system consists of the traditional heater core that obtains hot coolant from the engine, and two small electric heating elements. Until the engine has a chance to heat up, the amount of heated cabin air produced will be low since the electric heating elements produce the same heat as ~20% of a decent hairdryer.

 

Hi Stemchick,

In the winter your probably not running recirculate, as the windows would fog up. So, snow blockage between the windshield wipers and the hood on the passnerger side can be a problem. That is where the cabin ventilation intake vents are. You need to keep those clear for winter driving. If no air flows into that vent, no air flows across the heater core, and no heated air flows into the cabin. The aerodynamic design and location of the cabin air vents is such, that air pressure will not clear the vents, even at high speeds. The cabin air vent needs to be cleaned prior to driving. Once the snow is off the area use the brush in a hammer stroke to push any snow or ice stuck in the grill through.

I do not think there is a problem with the enough snow getting through the vent, and collecting in an area that is not heated. As the slots in the intake air vent are backed up by a black wire mesh, with only about 2 mm square openings. Of course if the snow collected by the heater core, it would jut be melted. I think the problem is more related to my comments in the first paragraph.

One alternative is to run with the windows cracked, and recirculate, if its sunny, and you have 1 or 2 people with dry clothes in the car. That way the humidity is ventilated, and air will flow over the heater core from inside the car and back. But typically one does not have a problem in sunny weather clearing the intake vent.

Also, check to see if your cabin air filter is clean. Its amazing how dirty these get. The cabin air filter is behind the lower glove box. There are instructions how to tilt the glove box all the way down to get to the filter in the car manual, I believe.

In weather below freezing allot of experienced Prius drivers will grill block. Being in Montana, I imagine you are familiar with this term. If you are doing local driving, on mostly cleared roads with limited highway miles, a full grill block is usually OK below 5 F.Below 32 F, a half grill block is OK for such driving. Without add-on instrumentation mountain driving, or continuous at-speed deep snow driving, or high speed continous highway driving might be a problem with a grill block.

We use polyethylene foam tubing from the hardware store, that is sold to insulate water pipes. Split it apart lengthwise and stick one edge in one grill slot, and the other edge in a slot further down. You may need to slit the tubing crosswise so it will fit around the vertical recessed grill slats. 3/4 inch diameter will bridge two horizontal slats (blocking three grill slots). 1/2 inch diameter will bridge one slat, and block two grill slots.

 

Don't expect much heat from engine warm up. NO almost certainly wasn't the case. It was likely just a minimum from the sub-zero temps.

With an aftermarket device, like ScanGauge, you can watch the temp of the engine coolant rise. That confirms all is well even before you can feel anything significant coming from the vents.
.

 

Hi Stemchick,

Was the engine running continously during this stationary period?

 

Hi Stemchick,

I am familiar with such temperatures. I spent time in Northern Michigan, on the Keeweenaw Peninsula during my child hood. Where it was common for me to walk to and from school 4 miles in 0 degree F weather. Christmas day I was out for a nice hour and a half walk in 4 F weather. During college there was a 20 below day, and of course they canceled school as people in Central Illinois are not prepared for such cold. So, I just dressed up warm and walked the 5 miles off to the Ham Radio club. I was the only guy there, so I had sole usage of the equipment. It was great. I can still remember the guys in my dorm giving me serious advice not to go, as they were convinced I would be found in a snow bank frozen to death.

I have also been out driving in 26 below weather, with 30 mph winds that happened some years ago here in Chicagoland.

There are a few Prius drivers up north of you there in Alberta and Manitoba. They can fill you in on grill blocking they use on all their cars, not just Prius. -10 to -15 F is common there in the winter.

 

Just sitting there stationary won't produce much heat.

It was -4°F on my commute home the other day. After 9 hours of leaving my Prius parked outside in the lot, I was getting decent heat at the 10-minute mark and was feeling pretty darn comfortable by the 15. There was no warm-up. I just pushed the button, fastened my seat-belt, then drove away seconds later.
.

 

I guess, this is a tip from my experience. After installing Wheelskin leather perforated cover, I can drive without the gloves on in the cold. It is one of those side benefits that you don't know until you have it.

 

Stemchick, did you set the command temp all the way up to max? I think when you do that the Prius kicks in the electric heaters to supplement engine heat. Also, force it to recirc mode until the window fogs up, then hit the defog button until the window is clear, then turn it back off and it goes back into recirc mode. This may help you.

I did this trick when I went north up to Flagstaff where the elevation was 7500ft and the morining temp was +3F. Setting the command temp to max gave me a little bit of heat until the engine warmed a bit.

 

Will defrost work in recirculate mode? I don't think it will, I think it automatically switches to fresh air.

I agree with Evan, to get it warm you need to drive it. Go around the block if you don't trust it the first time and park it if the heat doesn't work in 5 mins. If it does you know tomorrow all you need to do is drive it.

Is there a de-icing spray you can use? (I admit I know little of this problem)

 

Hi Stemchick,

Evan is right. It wont blow hard till the engine is warm. Until then it will blow softly, and use the electric heaters judiously (primarily for window defrosting). Did you know the car has two small electric heaters? When you smell the hot electrical smell, that is the electric heaters being used, but when the passenger air vent is blocked.

Heat flows from a higher temperature to the lower. When the temperature difference is greater, heat flows faster. Heaters and Air Conditioners just setup the circumstances where the temperature difference is maximised.

The Prius having a computer to figure this out does not turn on the fan until the temperature of the air available from the heater core is warm enough for efficient heat transfer. This creates the circumstances where the temperature difference is large, faster. Because it keeps heat in the engine. I am sure you do not run the fan high when its -15 F out, when you first get in the car, right? The Prius climate control is just doing this automatically.

In some other threads, I came to the conclusion for really cold weather it would be nice if there was a gasoline powered furnace in the car. This way, the car would get warmed up efficiently. Most of the engine waste heat goes out the tailpipe. And with the smaller engine the water jacket waste heat is too small a fraction of the overall waste heat. SO in idling the car you only get about 20 % of the energy from the gas. And as there is not much gas being used while the car is idling, that is very little heat. If there was a furnace it would be 75 % efficient, and the exhaust from the furnace would be very clean.

Some cold weather drivers have put an electric ceramic heater into the car to warm up the interior prior to driving. You want to be careful the heater is supported properly, does not blow directly on flamable materials, and cannot fall down unattended.

 

When you live in a state who's name means "wind", you may find you have more trouble with drifting snow than some others. It's fairly windy and snowy where we live, but we keep our Prius in the garage, so I can't say I've had the same trouble. I have had it happen with other cars when we kept them outside.

Tom

 

Been there, done that, didn't like it, decades ago back when I had to park outside. One thing we used to do up here, and some still do, if the car has to be left outside:

Take a tarp, about 3-4 ft wide and 6-10 ft long. Open the front driver and passenger doors. Unroll the tarp so it covers the windshield and cowl area, drape it over so it goes inside the car. Slam the doors shut

That way, the snow/frost/ice is kept off the windshield and cowl area where the HVAC sucks in its air. It looks ugly as hell to have this tarp draped over your windshield, but it WORKS

Or, you do what I do: have a well insulated attached garage, with a Reznor 35,000 BTU natural gas heater that is CSA certified for residential garage use. I'm getting too old and too miserable (Ask any of the forum members, they'll agree with that self-assessment) to deal with icy windshields and clogged heater ducts

 

You mean like this one?

BlueHeat® Main

Apparently, they are popular in Scandinavian countries, and they really do make sense. Especially if you can't plug in. For a diesel engine, they are probably mandatory, as it's difficult to cold-start a diesel engine in winter

The heavy trucking industry has widespread use of engine and cab heaters to eliminate engine idle time, which uses a lot of fuel and is hard on a diesel engine. There are myths that idling is GOOD for a diesel engine: bulls***, it's bad for the motor

The European Espar is popular for large trucks

Espar - HYDRONIC 10

The Teleflex ProHeat is another popular heavy truck coolant/cab heater

Teleflex Power Systems - Idle Reduction & Power Management Solutions

Going one step further, Teleflex/Carrier make a diesel powered APU for heavy duty trucks.

http://www.trucktrailer.carrier.com/Files/TruckTrailer/Local/US-en/trucktrailer/comfortpro.pdf

This keeps the engine and cab warm in winter, and the batteries fully charged (Very important in arctic temps!). In summer, the APU can run the A/C without idling the big motor, for substantial fuel savings

I would never do that. Although tempting, and it *would* work, it also seems every cold snap, there is a rash of car fires here when the electric heater manages to set the damn car on fire

 

I agree with jayman, he is a grumpy old fart!

If you want an electric heater in the car how would an oil filled convection heater go?