Electric Element in Heater

[MiMi]

In the thread "Interesting Mirage Quirks", 3plane wrote about the electric heating elements in the car heater. I recall that he said that they provide quicker heat to the car interior and faster engine warm-up. This is a very nice feature. I set my heater to "auto", turn the a/c off, set the temperature I want, and set the "mode" to the vent locations I want. From a cold start, the engine is warm enough to provide heat after 1 km, and the heater fan comes on at a medium speed.

On my typical 8 km morning trip, I was averaging about 5.0 l/100km during the summer but it now averages about 5.5 l/00km. I tried driving the same route with the heater totally turned off. i.e I pressed the "off" button. My fuel consumption went back down to 5.0 l/100km showing that the extra heat is not free. (I have done this a few times and the results are repeatable.) I think the extra comfort is worth the extra 0.04 litres of fuel on the trip!

[ahintofpepperjack]

I haven't heard about this before. Seems like a strange feature to include on an economy car, adding a significant expense to every one made. But I have noticed the heat is very good in this car. Better than most of my big V8 engined cars ever were. (Except my Grand Cherokee, That thing would give you 2nd degree burns if you put your hand in front of the vent!)

[Ares]

getting to optimal engine temp is important (apparently) to get good mpg; so much so that Toyota has technology in place in their current hybrids that pump the hot coolant into an insulated reservoir and when the engine is turned back on the warm coolant is pumped back into the engine.

[R01k]

In fact, for the size of it's engine, the Mirage has a very quick heater; much better than my previous '02 Altima that took forever to warm up the inside.

[Premeir620]

#22

Premeir620

Junior MemberJoin DatePennsylvania

My 2015 Mirage DE with CVT has the PTC fuse block. However, when I traced, no wires leave the fuse block. No heavy gauge wires to glove box area either. I purchased a DC ammeter to put on the feed to fuse block for PTC heaters, nothing, no amp draw. Conditions were 19F full blast heat set to 89F. My model is apparently missing the options?

[Tyrelirwin]

My 2015 Mirage DE with CVT has the PTC fuse block. However, when I traced, no wires leave the fuse block. No heavy gauge wires to glove box area either. I purchased a DC ammeter to put on the feed to fuse block for PTC heaters, nothing, no amp draw. Conditions were 19F full blast heat set to 89F. My model is apparently missing the options?

If someone HAD the option and pulled the fuse, would there be any other problems? It gets cold here, but my heated seats do the job for keeping me warm. I could use a bump in economy.

[Daox]

Here are the conditions of the PTC heater being used. Break any one of those conditions and it'll stop running.

Ok I got one. Not really a quirk but more of a hidden feature you probably didn't know.(I didn't).

Winter is coming for us on the northern half of the globe so you can try this one soon.

To augment heater performance the Mirage is equipped with an electric heating pad that is positioned in front of the heater core in the HVAC case. It warmes the air flowing to and through the heater core so it gives warm air quicker plus some of the heat gets passed on to the coolant circulating inside the heater core through this flow of warm air helping with engine warmup time.

Both automatic and manual A/C systems got it.

It is called PTC heater (Positive Temperature Coefficient) and it will operate under the following conditions:

-Engine running
-Blower fan on
-Temperature setting: any except MAX cool
-Outside temp 59 degree F or lower (ambient temp sensor is at top of lower grill opening on driver side)
-Engine coolant temp 167 degree F or lower
-Generator output 70% or less

It has 4 heating elements controlled by 3 relays. One of the relays run 2 of the elements and the other 2 has their own elements to operate.

These three relays and three 40 amp fuses are located in the sub relay/fuse box under hood right infront of the battery.Go check it! It's there! You know you want to.

This explains why last winter the few times I used the heater (Florida here) I got pretty much instantanious heat.

My 2014 DE has this. So, I don't think its an option. But, perhaps they removed it in later years for cost savings?

I can tell when the heater kicks in. Its most noticeable when you're stopped and idling. If you turn the heat off, your idle will go to the normal ~800ish. If you turn the heater fan on, even to the first setting, it kicks the idle up to about 1200 rpm.

I will say it seems like the heater's behavior is peculiar though. It doesn't seem consistent. Perhaps its because there are so many conditions? It would be interesting to run a LED or something to the relays to see when its actually on. And, does it always turn on all the heaters, or does it taper their use with increased coolant temperature? Its a mystery.

[Premeir620]

Finally found it, behind stereo the 2 thick white wires. Tested operation by jumping out at relays, all work.

[Premeir620]

Picture of PTC case with 2 thick white wires and one thin red and one thin blue

[Premeir620]

Relay box(tested all 3 elements with ammeter) working