Sounds to me like the vacuum pump, which the HVAC relies upon. When you turn the key to the "ON" position, you should hear the vacuum pump running for a few seconds, then shut off. The pump is located in the engine compartment. If it continues to run for an extended period of time (even with engine ON), or it doesn't run at all, then it's likely the culprit. If you purchased an extended warranty, have them check/replace it. If it's a problem you've inherited, there are youtube videos on how to fix or replace the vacuum pump.Just purchased a used 2011 f250 6.7 ... My blower motor runs find the vent controls seems to work but little air is making it to the Windshield on defrost and same when switched to heat.. Any ideals
I'm glad you pointed that out. With the known real-world reliability of of the 6.7L, I would have to assume that this is an improved design. I take it by your post that this is not as simple to fix when failure occurs? Maybe not as inexpensive, either.All the previous Navstar Powerstrokes had an electric vacuum pump. Which is what I had to change on my 6.0. It appears the 6.7L has a gear driven pump on the front of the engine.
Just purchased a used 2011 f250 6.7 ... My blower motor runs find the vent controls seems to work but little air is making it to the Windshield on defrost and same when switched to heat.. Any ideals