RandyA (Randy) offered photos of hos project in replacing his dash air valve. (note - click on images to enlarge)
All of the push-on connectors are pre-installed as part of the new valve. Included are new yellow and red knobs.
I had a Volvo repair bulletin that referenced taking out all sorts of stuff to get to the valve - things like the radio, fuse panel and, instrument cluster. I found none of those items need to be removed, but lifting out the instrument cluster did make the job a little easier since I could move the six air lines forward for reassembly with less tugging.
Anyway, this is what the dash on my 2004 Volvo currently looks like. Yes, I have moved some switches around and added some new ones as well. Pre-2003 models have the dash arranged differently and may require additional/different steps .
My first step was to gently pry off the lower trim molding (brown thing). It is held in place with spring tabs that go into plastic slots in the dash. The yellow arrows point to a tab and a slot. There are several along the molding so work slowly and carefully (yes, part of the pictured slot is broken, but it still holds the clip.).
EDIT ADDED on removal steps of trim pieces thanks to info from Ray Nomad:
"....looks like you removed that "wood grain" trim piece from left to right. The left side of the trim piece (to the right of the steering wheel) should have a plastic "hook" and that piece should come off from right to left. As the clips are released moving to the left the piece will pull to the right to disengage the "hook".
A little hard to explain and I don't have any pics or diagrams. Just the opposite is true if removing the trim piece to the left of the wheel. Seems like there are more of these trim pieces missing that "hook" than not."
On the very end of the molding there is a lip that slips under the front center fuse cover. You might want to remove this cover to get the final clip loose but I was able to do so with the cover in place.
Depress the spring pins (yellow arrows) that holds each knob on with something small like a 1/8" drill bit and pull the knob off - that is unless you are unlucky enough to have your knobs attached with roll pins.
Comments from Ray_nomand (Ray):
Me thinks your valve has been replaced before because you had those spring pins.
Also, looks like you removed that "wood grain" trim piece from left to right. The left side of the trim piece (to the right of the steering wheel) should have a plastic "hook" and that piece should come off from right to left. As the clips are released moving to the left the piece will pull to the right to disengage the "hook".
A little hard to explain and I don't have any pics or diagrams. Just the opposite is true if removing the trim piece to the left of the wheel.
Seems like there are more of these trim pieces missing that "hook" than not.
I elected to remove the six Phillips Head screws holding the mounting plate to the valve body. Be careful since removing this plate can cause all of the old valve plungers and springs to deposit themselves in your lap.
Take out the two Torx screws holding the right side of the cluster to the dash. Note these are threaded screws and NOT sheet metal like the other Torx screws. You need to know this for proper re-assembly. Gently pry down the upper molding over the cluster. Note: All orange arrows.
On the left side remove the Torx screw from the bottom of the light switch/vent bezel (black arrow), unplug the green connector (white arrow) by squeezing the lock tab on the bottom of the connector and remove the left instrument cluster retaining Torx screws (orange arrows).
You can now lift the instrument cluster out of the way letting it rest to the left of the steering column. This gives you access to the tubing bundle that you can pull a couple of inches to give you more access for re-attachment of the air lines.
Remove the valve by disconnecting the six air lines. I used a pair of needle nose pliers to push in on the brass collars (white arrow) while pulling on the hose. This is a kind of awkward maneuver but if you hold your mouth just right it will work.
Push the air lines into the fittings on the new valve following the same color position as the original. Be sure the lines are in tightly by giving each a tug to make sure they do not come loose.
Reverse the disassembly to put everything back together. I did NOT take the six Phillips head screws out and remove the mounting plate before installing the new valve. I had plenty of room to reattach the air lines with the plate on.
As Chet noted there is a repair kit for the valve. I intend to obtain a kit and rebuild my old valve for "the future" and just to do it. Now that it is apart I see that nothing more than new O rings, springs and seats are needed after the valve body is cleaned. On my valve one of the O rings had worn and slipped up creating a leak.
Everything from start to finish took about an hour, including making photos. I think I could cut that time in half if I were doing it again.
Question from SuiteSuccess (Carl): One other question, did you trim the ends of the lines before reinserting? And what was the part number, blurred on the pic?
From RandyA (Randy): No, I did not trim. The 3/8" air lines appear tougher than the 1/4" and did not show a "depression" where the fitting grabs the air line - the ends were perfect as-is. I did clean them off with some alcohol before putting them into the new valve.
To avoid any part number errors it is best to give your Volvo dealer the last 6 digits of your VIN when ordering a part like this valve. While I suspect it would be the same valve on your 2006 as my 2004 I would hate to be the cause of a wrong part should some differences exist. Best to be safe and get the part number for your truck from your dealer shop.
More from RandyA (Randy):
Looks like an easy rebuild. I have not checked to see if Volvo has a kit or if I have to look elsewhere. If you find a source before I do please let us know. From the info in the .pdf I shared in my original post it looks like the kit might be the Haldex RN31BF but I need to recheck valve part numbers to be sure. BTW - The new valve ended up being less than originally quoted. I was charged $230 which included tax and shipping.
EDIT: I think I found the kit. Look here. $30 is better than $230 if you have time and patience