I have a 2000 ford f250 diseil. The air conditioner blows cold but it all of a sudden stopped blowing out of the vents on the dash. It still blows cold but it only blows out of the defrost vents by the windshield. I have no idea. I put it in 4 wheel drive and it all of a sudden stopped blowing out of the dash vents. any suggestions? I am broke and cant afford for the dealership to take me to the bank. Any help is good. thanks alot kyle

 

The default position for the vents isthe defrost mode/position.. Should be default to defrost in heat mode as well.. The diesels have a vacuum pump mounted to the R/Passenger side inner wheel well area to supply vacuum for the climate control as well as ESOF auto lock if equipped.. If the pump fails, or a vacuum leak develops, the vents will default to defrost.. Pump failures are fairly common, but it should be 'run tested' and checked for a possible system leak.. If a vacuum leak is present, generally the pump will continually run.. Also check for power distribution to the pump, but if the fuse blows there's other components affected that would show up...

Here's a pic of the vacuum pump...

[IMG]local://upfiles/6756/8DBD29D40DB1447CA57A3E004CB2C0CE.gif[/IMG]

 

Is your truck a Manual hub/T case, or ESOF Auto Locking hubs?

 

thanks for the reply. It has manual hubs. It all of a sudden started blowing on all vents. I have no idea what is going on. sounds like something might be going bad. any help appreciated. kyle

 

Did you check the electric vacuum pump?

 

Just experienced the exact same problem. I have a 2000 F350 that has been sitting for about 6 months and this summer had that problem. It would go between air and no air blowing out of the vents about every 30 minutes. After making an appointment to have it checked it just started working properly on its own. Hope it stays that way