Had some strange behavior this morning. Ambient temperature is 45° F.

I was going to work. My route is a bendy farm road where I never get up past 50 MPH. The heater was non-functional except for the defogger setting and blowing lukewarm air. The temp guage was reading in the vicinity of 45°C or so
The last section of my 15-mile drive is a 2-mile hillclimb (out of the Snohomish River Valley for you Seattle area folks) up about a 5% grade. I was turning onto the road from a stop so it was floored and on boost hard until I got to 55MPH or so. During this climb I really put the screws to the engine and the temperature climbed to just shy of 70°C in my estimation. The heater was now blowing nice, hot air on all settings.
So I have two questions:
1. Why did it take so long to get to operating temperature? Is this normal? Engine was running fine and had plenty of power (so to speak).
2. Does the climate control system have a feature that locks out all the heater modes except for defrost at low coolant temps?

I'm beginning to wonder if I have a stuck-open thermostat.

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1978 Ford F-150 351M
2002 Kia Spectra 1.8l 5-sp
1985 Volkswagen Scirocco 8V 1.8l 5sp
1985 MB 300D Turbo California

"Die Natur verabscheut Vakuum"