I have an 03 dodge diesel and after driving about 30 or 40 miles with the air on max it starts making a grinding sound and the fan doesn't put out much air through the vents. The fan sounds like it's running on high. Has anyone had this kind of problem or know what could be wrong. I didn't know if it was freezing up or what. The lines by the AC dryer are covered in frost. Any help would be appreciated. Thanks

 

frosted lines is a sign of low Freon charge, start there then see what happens...

 

The blocked airflow is likely due to the evaporator freezing up.

I had an 03 that did that. The dealer relocated the temp sensor, which helped.

Putting it on recirculation seems to help, once the air in the cab dries out.

 

Mine did the same thing, couldnt figure it out. Mine did it all the time though. You can do what I did and take the fan off and inspect it. Its on the right side cab of truck and is easy to remove only three screws holding it. Once you do that you can inspect the vents and the fan itself. What happened to mine is that the flap that either recirculates or gets fresh air broke off and was blocking the fan from getting any air to the vents. Put some glue on it and have not had that problem again.

 

Same on my 06...the fresc/recirc door breaks and the blocked airflow makes the fan growl.

 

They have bad doors that breaks easy also check the charge this will happen if low on charge.My 03 was low on charge.