1990 HVAC

i have a 1990 s4 127K miles i have a HVAC problem for no reason the solenoids will start open and closing real fast and can't get them to stop has anyone had anything like this happen before ? if anyone can help my email is jak462@aol.com my cell 818 599 9948 thanks

What solenoids are you referring to? What is the general location of the components/solenoids, and what is it they're doing that makes you say they're opening and closing? Are they making sounds of some sort?

Hi they are the solidionds that activate the pods to open and close different vents be it the air flow going to the center vents or to the floor or defrost ect they have all the different vacuum hoses coming in so its in the lower center of the dash if you open the driver side panel you would see the vacuum line thats there it is and as I'm driving for no reason they would get activated and fire off real fast thus opening the pods i had the pull the brown ground wire that dos to that unit to make them stop and if I'm driving and i hit the brakes that makes them go off too . have you and idea what it could be?

The most common cause of what you're describing is that the rubber diaphragms in the control actuators for the various doors in the HVAC ductwork have developed holes and are losing vacuum. Check out to following link which explains what's happening and how it can be addressed, and give Jeannie a call at www.928gt.com for the parts you'll need.
dwaynesgarage.norcal928.org/1987%20HVAC%...pair%20Procedure.htm

ok ill check that out thank you very much

Just wish I could have provided better news if it IS the HVAC vacuum diaphragms, since the job to replace them isn't the easiest project to complete on a 928.