2004 Honda.
Car runs fine and no evidence of leaking radiator fluid or obvious concerns with water pump, etc. Car warms up fine and hot air blows fine while driving (cold right now in Indiana!) but when pulled up to light to idle the blown air gets noticeably cooler. heats back up when driving. Also, heats up when pressing down on accelerator during idle (car in neutral).

Someone suggested thermostat stuck open but don't see how that makes sense if it would open anyway once car warms up???

pete

 

welcome to the forum, you are correct, thermostate does stay open, and the cooler water at idle does go through. you can put in a thermostate that opens at a little higher temp, this allows the engine radiator water to run a bit warmer, but if your summer gets hot, the thermostate needs to be changed back.

 

ok....so what you are saying is even though the coolent is ALREADY hot and is blowing hot air that when the car is idling the blower motor actually starts blowing cooler air because the water has cooled down?? This seems unlikely??

thanks.
pete

 

this is an example, if you have a 160d thermostate, it will open at 160 and cold air from the outside mixes with the 160dwater circulatingand cools the warm air.( colder in winter ) If you have a 190d thermostate, the cold air does not cool off the warm air as easy, The water temp stays hotter. The water in the radiator system doesstay cooler in winter. Imay not be explaining thiscorrectly, for this I apologize.