From time immemorial and certainly in 1950, a car heater was turned on and off and the temperature adjusted by a valve in the hose that sent hot water to the car's heater core under the dash.
But that meant when you turned on the hot water, it took time heating the core before the core would radiate heat. Even the hose leading to the core probably cooled off the coolant somewhat.
In the 70's? or 80's or 00's? some designers started sending hot water to the core all the time and using an air blend door to determine if cold/room temp air came out of the vents or if warm/hot air did. Then it only took 3 or 4 seconds to change the temp of the vent air.
But what about people who live where it's never cold? South Florida? Panama, Ecuador, Hawaii, French Equatorial Africa. Do the cars there have a hot heater core only 6 inches from inside legs of the driver and passenger? Doesn't that annoy them?
Not sure if it circulates all the time or not. My present car I bought in October of 2017. I set the temperature to be 72. I've lived where is was a bit below zero and as high as 98 and baking in the sun. Once the car runs a bit, I'm comfortable. In extremes, I use the remote starter to heat/cool a bit before I drive.
In really cold weather, the heated steering wheel is nice too.
Well I checked just now, and Camrys aren't the only ones.
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your heater hoses, if there is a control valve in one of the hoses it does not flow all the time. No heater control valve...then it flows all the time through the heater core. -- Exactly. In virtually every modern car coolant circulates through the heater core 100% of the time- interior air temperature is set by one or more blend doors in the HVAC ducting. -- ^This! If it doesn't have what was commonly referred to as a Ranco valve you can fit one easily, it will improve A/C performance on older cars that may have a leaky blend door and save undue stress on the heater core in the summer. Many types are available manual, vacuum and electric some even with a rheostat. -- Hmm... I wonder if lack of a shut-off valve, a leaky blend door, or some other form of heat leakage might be why my Prius blows warmer than outdoor air when heat and AC are both supposed to be off. It's very annoying in mild weather. My brother has the same complaint with his '95 Avalon. My Mazda had a proper coolant shut-off valve AND blend-door temperature control.
I will have to look into a Ranco valve. ... Ranco makes lots of really complicated valves. This is just a check valve:
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is more stuff but not what the guy above is talking about.
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the first 3 pages above just show different versions of the same thing. For a little of everything, page 4 is the place:
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might have in mind the H42-valve. This is for several differnt models:
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Since I don't need one, I'm not looking any further. The way to find out would be to ask a mechanic or at an auto-parts store.
BTW, I see that the Ranco valve is not what I once wanted, something unrelated to this thread, that would, for the winter, turn the heater fan off until the coolant warmed up, so it wouldn't blow cold air on me. But this car warms up quicker than some earlier ones so it's not so important. (Ranco valves limit or stop the water flow, usually in the summer, not the fan.) I did put a thermostatic switch for the fan in my heater hose once, but I can't remember what happened after that.
Some, maybe most heater cores may be farther from one's legs than the Camry, but an advantage of Camry is that it's pretty easy to change a Camry's leaking core because it's so accessible.
Until the 60's, everything was an option... even a heater was an option in some cars. It's been standard in all cars for a long time, and I imagine that carpeting and modern insulation take care of the issues with the heater core which you are suggesting.
The reason for the design change, and the elimination of the mechanical water valve, was the move to factory AC as standard, in particular - climate control. The delay you speak of is the reason that valve had to go. It was far more practical to adjust temperature with a blend door where temperature change was, for the most part, instantaneous. Couldn't achieve that if you relied on controlling water flow. Getting rid of that water valve was once of the best things that ever happened to car heaters. It was the source of many issues and without it the heater core gets a continuous flush every time the car is driven.
No because if you live in that climate you use the AC. For that matter, I use my AC summer and winter. Summer for cooling, winter for demisting. Works for me.
THANK YOU! It seemed insane to heat/cool the car by ALWAYS using a combination of hot/cold air. I first noticed this on my mom's 1988 Caddy, but I figured that insanity was the norm for Cadillac.
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