Hino 338 heat not working

[tete]

My 2010 Hino 338 heat is not working. Ac works but no heat. Changed the thermostat but still doesn’t blow hot. What could the problem be?

 

[Hino123]

I would check the heater hoses going into the heater core and make sure they are getting hot. If the hoses are warm to the touch, then you could have a plugged heater core, a binding mode door or heater control cable binding. On the thermostat there is a “jiggle valve” that floats around on the thermostat. The “jiggle valve” should be in the 12:00 position. It most likely would not cause a no heat issue but… just keep it in the back of your head as something to check. Let us know if you find anything.