That brings up another question. Newer vehicles get heat out of the vents much quicker than many of the older cars did. Even on the coldest of mornings. On both my 2015 Jeep, and 2018 Toyota, I will have noticeable heat coming out of the vents, within just a couple of minutes of starting a dead cold engine. Usually as soon as the engine drops out of high idle, and I back out, I can feel the heat. Back in the 70's, it seemed you had to drive much longer and further before you started to get any heat. What did they change to accomplish this? The newer vehicles seem to produce noticeable heat long before the temperature gauge even moves. Where on the older one's you would see the temperature gauge move well off "Cold", before you got ANY heat out of them. And I'm talking about when they were new. Not after 70,000 miles with a neglected cooling system, and a clogged up heater core.
Originally Posted by AEHaas
Most sensors measure water temperature and it warms up within minutes of starting the engine. That is why you can get heat for defrosting and for the interior in winter. AEHaas