Well Finally started getting Cold here, turned the Dial all the way to its hottest point i get Hot air, then as i slowly back the Dial up it stays warm. Yet if i just turn it to Warm i get Luke Warm/Cold air. Is this the thermostat going bad?

Also Regardless of the heat setting, it makes a rattling noise, i can not tell where its coming from sounds like from the vents themselves. Sounds like i have a gargola living in my heating system. Any ideas?

 

Wonder if the switch is getting worn out. I changed my wifes heat controls in a gmc envoy for the same reason. Worked for her but may not be the issue you are having. Good luck. Someone here will have more constructive input I'm sure.