Not much air blowing out the vents.

Kenworth is notorious for burning through blower motors in dusty conditions. They don't put cab filters on the trucks from factory so that dust gets in there and takes out the blower motor.

 

hi...I have a 1999 freighliner conventional and I have a problem with the a/c. When I turn the ac on, its blowing the cool air to the outside of the evaporator hose and the vent, defrost only blow little air. Can someone tell me where can I start to diagnose the problem. Thanks

 

Can you post a pic of your heater box before and during removal

 

Kpeterson
What fixed your low airflow from dash vents and defrost?
I have same problem and have replaced all parts that do not require complete box removal. This seems to be a common problem with a 2000 W900

 

Your evaporator and heater core are likely mostly blocked with fine dust and debris or cottonwood fuzzies. I have pulled them apart for a through cleaning but no way to do it assembled and be good enough to make any difference. Either that or replace both with new while your In there. They dont really blow the hardest to begin with IMO.

 

I agree with the squirrel cage symptom. My friend had a similar problem. Once he cleaned it everything worked fine. That’s not to say everything everyone else is suggesting could also hinder it. Plenty of good suggestions here. I ask a lot of questions and get a lot of good help here.

 

The metal shroud around the squirell cage on My 1998 T800 was rusted out on the bottom and blowing air into the engine bay

 

I came here to check out some options for my same problem. 2012 Kenny. This truck was new to me and had just a small about of air blowing into cab. After brake kleening the heater core and checking for blocked vents, still had hardly any flow. The last resort I tried was to switch the wires around on the motor. Low and behold I have the proper flow into the cab now. Just thought I would add this in case someone needs the info.