Heater coolant loop control

I have noticed that if I leave the temp control set to a high temperature, and turn the climate control OFF, I get warm air flowing through the vents when I move the car at speed.

When the temp control is set low, this does not happen.

So I deduce from this that turning the climate control off does not close off the heater coolant loop.

Does this affect ICE warmup time? I mean, if I leave the temp high, and climate control OFF, will this cause it to take longer for ICE to reach S4 temp?

I know that leaving the climate control ON with temp set high will cause ICE to run rather interminably. But does it make a difference when you leave it off whether you have left the temp turned up or down?

 

No, my grill is not blocked. At freeway speed there is a nice little flow of heat with the fans off, as long as the vent is set to open, rather than recirculate.

I'm not particularly concerned with the electrical draw of the fan on low. The concern is that if the fan is on at all, the car continuously burns gasoline until the cabin reaches the set temperature.

So it is clear to me that with the temperature set high, that the coolant is flowing to the heater core, even with the climate control off. What is still somewhat unclear, is whether this "free" heat is heat that the ICE is intending to dump into the radiator, and is thus truly free, or if allowing the coolant to flow through the heater core at low ambient outside temps is going to be somewhat parasitic to the engine, even without turning the climate control on.

Ideally, I'd like to figure out how to set the thing so that the fan will run on low, and the engine will give me only extra heat that it intended to dump through the radiator.

Bob: Yes it is engine heat, but it is coming from the heater core, via coolant from the engine. So the question is what effect opening that valve and allowing coolant to loop through the heater core has on MPG.

 

Ah, so you are saying that by allowing flow to the heater core, you are taking heat from the engine before the thermostat has opened and allowed flow to the radiator.

So, just leaving the temp turned up above outside ambient, even with climate control OFF, will mean it takes more time for the engine to get up to S4 temp.

So if I want the ICE to warm up fully before I steal heat, then I have to leave the temp set to cold, and then watch the engine temp (gotta get a gauge), and then when the engine is warmed up, turn the climate control on and turn up the temp, and then turn the climate control off to make sure the engine doesn't run extra on my account.

And don't forget to turn the climate control on, set temp back down, and turn climate control off, before shutting car off.

Really?

 

My understanding is that grill blocking is beneficial primarily for aerodynamic reasons. The engine will not flow coolant through the radiator unless it has extra heat to get rid of.

I doubt that grill blocking has a significant effect on warmup time. The airflow making it through the radiator and hitting the outside of the block isn't going to be too significant compared to what is effectively a couple hundred pound solid chunk of metal, oil, and water.

Correct me if I'm wrong. Somebody probably posted measurements somewhere.

 

Much thanks to those who suggested grill blocking. I blocked off all but the very bottom strip. Works amazingly well!

As a side note, with the grill blocked, I no longer get airflow from the vent if the vent is open and the fans OFF. I don't actually know where the intake is but I'm sure the grill block blocked it.

Anyone know exactly where that intake is?

 

Ok. I went and studied the air vents for a while. At first glance, you're right. I basically had to call myself a liar or an idiot. It looks like there's no way that grill blocking could decrease the flow.

However, after staring at it longer, here's my hypothesis:

I believe that the air traveling over the hood/windshield will create a low pressure zone over the intake area. The exposed vents are angled with the flow of the airstream, not facing into it. But, as the cabin has vents toward the rear of the car which would create negative cabin pressure as well, I think it balances out so there would be minimal pressure difference.

But if you look carefully around the sides of the cowl, you can see that the air intake is not completely sealed off from the engine compartment.

My guess is that the huge pressure in the engine compartment at freeway speed forces air around the gaps on the sides between the cowl and hood, negating the vacuum created by the airstream over the hood, and thus allowing higher pressure than the cabin.

 

Yes, I've had it blocked for at least a week now. Works like magic. I blocked everything except the very bottom slot. I probably could block that too, but I'm afraid of overheating the inverter and I have no instrumentation as of yet. I haven't heard the fans turn on yet, so I'm sure the engine is OK. I don't know if the fans turn on to cool the inverter or MGs.

With the block in place, I can steal heat for the cabin and still get better efficiency than before the block with the heater off.

But I'm still annoyed at having to push the temp button a million times or hold it for a million years to switch between having heat and just air.

Maybe somebody can explain to me exactly how it works. Is the heater loop digital? I mean is it something where it is either flowing or not, as opposed to having variable flow?

Or is coolant always flowing through it, and the climate control only adjusts whether the air flows through it or bypasses it?

 

Ah, good. Back to the original reason for this thread, then.

The "aversion", as you put it, is not to the current draw of the fan. It is to the fact that when you leave the temp control to a temp higher than the current cabin temp, then as soon as you turn the "fan" on, it turns the #%#&! ENGINE on to help make the cabin warm faster.

I don't WANT the engine to run to make me warm. I simply want it to give me WASTE HEAT.

Furthermore, sometimes I just want fresh air. Once again, there is no way of doing this!! If you turn the fan on, the climate control will look at the temperature and either run the engine or the AC.

Basically, I guess I'm saying that for as much as I love the technology of automatic climate control, I miss the old school fan knob and heat/cool slider, with discrete AC button. Heck, it even used to make me mad in my last car that there was no way to shut off the AC compressor in defrost mode.

 

I like the idea of blocking more. What is the highest inverter temp you have had with a fully blocked grill vs unblocked?