1991 T10 Tahoe 4x4 Blazer 4.3L

Whenever on cruise or accelerating up hill the air quits circulating from the AC vents. Almost positive the fan is still running. As soon as I top the hill it starts operating as normal.

I'm figuring some type of vaccum problem but not sure where to start looking. Any suggestions? All other vacuum operated devices work perfectly.

Thanks in Advance.

 

Hi RDHACK; I´ve exactly the same problem !. Q: did you solve it ?. In this case (+ positive) I´ll appreciate your comments.

I´ve the engine outside de vehicule, repearing broked rings, and this is a good time to resolve also this other malfunction.

Regards,