So I have a 2013 is250 that I’ve owned for almost 2 years now and everything was working as it should. But now my heat is not working and I live in New England so I need heat in the morning and cold air in the afternoon. My cold air blows fine but my heat is not working. I noticed when I would warm my car up in the morning with heat on, the car would still be cold. But after driving on the highway it’ll warm up. Now driving on the highway it won’t heat the car at all. My operating temps are normal and I have no check engine lights or vsc. Any ideas what it could be?

P.S I’m aware that there are threads for this issue already but I want some insight on the specific issue I’m having.

 

Have you checked your coolant level? Not just in the overflow bottle, but by actually removing the radiator cap and making sure coolant is up to the top?

The progression from heat only at higher rpm to no heat suggests an ongoing coolant leak, possibly a water pump on its way out. Suggest that you address it sooner rather than later.