97 960 Wagon 216K

(This is the same 960 with the fuel rail and radio issues--I'm posting each question separately so they can be answered more easily)

I'm getting an odd hissing sound inside the cabin while driving. The sound appears to be coming from midline of the car's dash region, perhaps near the windshield. Periodically the hissing will stop for about 5 seconds before resuming. The stoppage has no relation to what the car is doing. It may stop while the car is in motion or not. I have no idea what this is. Any ideas?

Thanks as always.

az

 

1- That's where generally the Climate Control vacuum lines, controller and devices (controlled by vacuum) are. They basically change direction of air flowing thru various vents. It does not affect the engine, since there is a vacuum reservoir there too, which dampens small leaks.

2- Another possibility is the connections of air ducts to the air box. Airbox is the hub where are individual ducts run from. Something can be leaking there too.

First I would check if there is any relationship between engine rpm and hissing noise, regardless if the car is moving. At high rpm, there is less vacuum; less rpm = higher vacuum. I would also check to see if vents operate properly when using the selector ****. If they do, it might be # 2.

 

Second the climate control , control box, vacuum lines and would just like to add.the control servo bellows. I've got two bad ones myself,( but that is another thread).


On the 960 with automatic climate control the control box is located under pass dash behind the crash bar. I unhooked the vacuum lines going to the control box and manualy operated / tested each bellows as well as the heater control valve while operating the heater/ac with a mighty vac to insure they worked properly. I found two out of the three or four bellows were bad leaking. I understand the recirculation one is not that bad to replace. I don't nkow about the others. I've got mine kinda hot wired till I can round up the parts.....

Good luck

 

Maybe this will help

 

Thanks, Red.

I'm having trouble reading the second diagram. Is there a way you can make it bigger?

az

 

Here

 

I'm not where i can resend it, however if you download it ,scan it for viruses, and then open it in a veiwer that has a zoom feature you should be able to see it. If you still needit Monday respond and I'll send a bigger version when I get back to the office.

Hope this helps,