1996 850 Wagon Service Light On Topic is solved

Post by **abscate** » 05 Dec 2016, 13:05

The flap is vacuum actuated but thermally regulated. If I remember this right, the thermal switch controls the amount of vacuum that goes to the flap motor.

A vacuum leak would kill your brake boost and cause wonky idle - looks like you are on right track.

PeteB · Post by **PeteB** » 05 Dec 2016, 16:24

I don't remember a vac line going to the bottom of the air box, but I'm not home
right now, have to check. Maybe it broke/fell off?

Post by **abscate** » 05 Dec 2016, 17:17

I think it's two vacuum lines to the rear or front if the box.

One supplies vacuum from the tree, the thermostat valve then controls how much is sent to the second line, which controls the flap

Post by **erikv11** » 05 Dec 2016, 18:07

Pete that vacuum line post we discussed on the previous page shows where the lines got on the airbag, give it another look. The pics are all from a 96 NA, same car as yours.

PeteB · Post by **PeteB** » 05 Dec 2016, 18:55

OK it had fallen off, lol! I should just plug it at the tree when I do the air box mod, correct?
Edit: I'm thinking this is wrong since it needs the vac to get pushed against the screw and
go the other way in cold weather.

So it seems that if you remove or clamp the vac line the flap goes to half open so this might
be another way to control it on cars without the flap mod.

The right angle vac connector at the air box just cracked in half, guess I have to try to
find a replacement.

PeteB · Post by **PeteB** » 07 Dec 2016, 01:01

Thread on doing the CV boots: https://www.matthewsvolvosite.com/forums ... =1&t=78859

PeteB · Post by **PeteB** » 07 Dec 2016, 07:29

deleted ....

PeteB · Post by **PeteB** » 07 Dec 2016, 10:10

Back to the vac lines, there is a lot of hard plastic tube that doesn't fit tight
in the vac line that I have, do you just replace it all with vac line? The vac
line that I have is also loose on the nipples, seems I need a smaller size.
Going to search on here to find out if the size is mentioned.

PeteB · Post by **PeteB** » 09 Dec 2016, 11:06

Did a compression test since it has been running very rough at idle, no misfire
codes so probably a new vac leak. Results were 155 PSI in 4 of the cylinders and
160 in the last, going to call that very good:
https://www.matthewsvolvosite.com/forums ... 04#p424504

PeteB · Post by **PeteB** » 10 Dec 2016, 10:36

There are two mouse nests under the hood, one on top of the transmission.
Any suggestions to keep them away?
They might be eating through the vac lines.