Heater Question

[police251]

So when I turn the heat on after about 3 min I hear a pop that can also be felt when siting down I dont know what it is but have looked. This sound does not go away when the system is on the heater seems to be working good but the pop sound I dont think is normal.

Have any of you had this sound before or could tell me what I need to look at. Thank you and hope you all had a happy holiday season

[amdriven2liv]

I was concerned about that sound, mine is a thump. Was told it is the "blend" door. The blend door is your heater/air conditioning box on the passenger side in the cab.

[Galaxie]

My 06 does NOT do it. My 99 Does. No issues.

[police251]

i could be a thump as well be you can feel it in the seats, is this how yours is just seems odd lol

[thomaslord84]

My '94 F150 does it but my '03 F250 doesn't.

["WTF" Stroker]

I 05 does it from time to time. only on warmer days. 30+* outside