Next issue: AC Vents go from OK to not OK.

1998 TDI Beetle 1.9

OK so I just took my car down to my trusted AC shop in Miami. Place does approx 75+ cars per day, and hence very good prices. 18 AC mechanics working on average day. Got a rebuilt Bosch (I think) compressor installed with new drier ...Now I have nice ice cold AC again which is sort of a necessity down here like 51 weeks per year.

I know even prior to this my ducts or my AC control unit is not right because my control does not go all the way to change to "Defrost" position and I do not think I get a defroster. Sort of bounces back off the spot. All other positions are halfway there with the "Dash" vent position at least being decent enough to get I guess about 3/4 air flow.

Now my issue I noticed which may be new, is driving back from Miami 1 hour and also last night after maybe 30 minutes of highway driving with the control on the "Dash" position all my vents practically quit on me. Airflow goes down to like 5% or less. When this happened I shut the stereo and I heard a fairly loud fan type noise from under the passenger dash above the glove compartment. What is strange to me is that after getting back on the local streets for about 5-10 minutes the airflow goes back to the 75% or so level..

I own the N.B. for about 5 months and when I first got the car I had some of foam come out of my left drivers vent so this could be 1 problem. I also have the somewhat defective Control unit that doesn't move up to "Defrost" and now this new noise and air flow going down to near nothing....

Is this possibly the AC Control Unit or am I looking at the blower motor going bad, or even worse having to rebuild the blend door under the dash?

Any tips on diagnosing are appreciated.

Edit. Just drove down to Miami and back. So on the way down AC blowing cold & vents are good. Not great. Then after like 40 miles the vents went to like 5% force. ( AC still very cold ) So I pulled off the highway to take a break and make a phone call for maybe 10 minutes...& I got back on the highway the air started blowing good but now about 55% strength. THEN I hear like a thump in the dash ( like a blend door noise? ) and the vents go back to full strength for the rest of the way down like 10 miles...
We drove down to Kendall like 20 minutes of highway and back 20 , then I drove back home the 50 miles and since the thump / whack my vents stayed strong. Hopefully something was stuck and loosened up back to normal, but will see how things develop I guess over next few days.
If anyone has any idea what may be going on here please chime in .....
AA

Will bring it back to the AC shop. ( no bump)

I had a similar problem. Turned out to be a portion of the cabin filter had frayed (did not maintain it properly) and it would separate from the edge of the filter lining and un-flitered air would pass thru - then clog up again and restrict the flow. Had to clean out the fan housing also and get all of the crud. Not forgetting the evaporator that was changed due to poor and non existent PM work. I do it on a regular basis now!

Thanks I do need to check that thing.

Austin

PSB Houston said:

I had a similar problem. Turned out to be a portion of the cabin filter had frayed (did not maintain it properly) and it would separate from the edge of the filter lining and un-flitered air would pass thru - then clog up again and restrict the flow. Had to clean out the fan housing also and get all of the crud. Not forgetting the evaporator that was changed due to poor and non existent PM work. I do it on a regular basis now!

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