What did your ammeter show when you did that test? Conservation of energy - resistive heaters should be 100% efficient or very close, if there is that much current flow the energy must be going somewhere...

 

You are right about the supplemental cab heater. I have that option but it doesn't work nearly as well as I had hoped. As for instant heat, forget about that, especially when the temps are cold out.

Ford missed the boat not developing a front winter grill cover and bug screen. They are both invaluable accessories. When I asked Ford about them I get the "They don't recommend them as the truck doesn't need it." But the thing takes a long, long time to really heat up in the cold. I have the heated seats which is a big plus but really miss the winter cover and also bug screen to keep the critters off the front in spring, summer, and fall. And we have a lot of bugs driving on the highways with bush all around. We call it bush up here and not the forest. It is like driving through a swarm at times.

 

The Ford service manager here in Great Falls gave me the same Bull S.
The Truck will start and run at -34*F......I've started that low without being plugged-in. However, that does not mean that is the best way to treat the Truck. The block heater helps with oil flow when first started....This is a Plus! A winter cover would help the Truck get up to Proper Temps sooner and therefore provide better mileage and less ware & tare on the system as a whole.

Note my post above....#12
I am going to get a cover for next winter!

 

You should maybe try not running the fan on full blast. With the auto climate setting mine almost never runs full speed and my cab is warm 10-15 min after starting it. I've heard people claim if the fan runs on high it moves air too fast and doesn't get warm as efficiently. Whether that is true or whether they improved the heater in later years I do not know. Mines a 13 and works good.

 

the heater core on your truck is basically a miniature radiator. The more ice cold air you move through it the more it cools the water. I always warm mine up with the fan on low. It does make a difference .

 

I have the supplemental cab heater and the winter grill cover. The grill cover definitely helps the truck to warm up faster, but even after idling for 10 minutes, it still takes several miles of driving before the needle begins go move off the peg.

As for the supplemental cab heater, I love it. I drove from Seattle to New York last month. Temps ranged from -34 degrees F to a balmy +20 deg F. I did not have the grill cover installed. I would remote start the truck and let it idle for a few minutes. By the time I got in, the cab is very warm and the temp needle was still buried on cold. During remote start, the computer sets the temp to 72 deg and the fan to low. If I kick the fan to high right away, the cab heater can't keep up and it starts blowing cool air.

If you start your truck, set the heater to 72, fan to low or medium low and let it idle for 10 minutes, it should be blowing really warm air. If not, I think I'd have a chat with the dealer cause something isn't right (or mine is a fluke and works better than it should).

 

I guess that supplemental heater is working out well. Even though I haven't seen below zero temps, I can tell you that idling the truck does about ZERO for getting it warm. Not until I start driving or getting the truck off idle does it produce heat. This is pretty common with diesels.

Also, if you let it idle too long you could wet stack, which is why even Ford has a built in way for a elevated idle control. (SEIC mod) A lot of people in the cold climate do this and hook it up to upfitter switch, a resistor determines the new idle when the switch is flipped. (some people even use rheostats so they can dial in the idle they want based on current conditions) Even the truck knowing it is cold outside and idling up can sometimes NOT be enough. I also think they did this for PTO applications as well.

Don't confuse my thought on that the truck doesn't warm up for you, with meaning just start up, jump in at -20F and hammer the go pedal. Some idle time is good, 10 minutes probably too much. I think that just wastes fuel. I always take it easy the first few miles too. I actually take it easy just out of the driveway even if its "warm" out.