The Unexpected Climate Control Vacuum Leak in our Volvo 240

It only leaks until it doesn't...
Ever since we revived our Volvo 240/244 I've noticed a massive "hissing" vacuum leak coming from somewhere behind the dash.
Here's the link if you want to see the first start!
• Will the ABANDONED Vol...
This hissing/sucking sound happens when selecting floor, defrost and recirculate modes - but its loudest when defrosting. I decided to go on a mission to find out what was actually leaking.
As an armchair mechanic myself - the most common issue people online report was a leaking HVAC check valve located on the intake manifold. While I don't believe ours is faulty, it looks awful and has some very small cracks forming. I took this time to install a Bosch replacement check valve and replace all the 3mm and 10mm vacuum lines with silicone tubing.
Not-shockingly... Nothing changed. So I dismantled the center console and started tracking down the issue. After digging around back there I found that the defrost diaphragm/actuator had come unplugged. I've seen this before unfortunately - after an aftermarket car stereo is installed - someone accidentally unplugs something or rips out a climate control vacuum line while pulling extra slack on a harness. Once plugged back in - everything is ready to go!
Hope this helps some of you guys and gals figure out your leaks!

[@andersf5464]

No shit talk about a Torslandatraktor, please. This is the best car ever made. The apex of petrol car evolution. The epitomy of motorized transport. The...
Trust me - I have fippled with a load of cars. My 245 ('Waggon') '93 is carefully maintained and brings me joy, aswell as everyone else. First words: Not for sale!

[@matthewb2651]

Watched your video and fixed my problem in 30 seconds. The main vacuum line wasn't connected to the engine! I never noticed it but now defrost, recirculate, and floor air work perfectly. Thank you.

[@MatthewFinlay]

Dude that’s awesome and glad I could help! Thanks for watching and I hope you got a laugh as well as working climate controls!

[@thisisyourcaptainspeaking2259]

Nice job! I found a bank of vacuum solenoid valves mounted on a pcb under the passenger side dash in my 2000 buick, each and every solenoid coil soldered to the pcb had begun to break the cheesy thin solder joints. 10 minute session with a roll of rosin core 60/40 on the bench and everything was good as new!

[@MatthewFinlay]

Choose your problems haha leaky or finicky vacuum systems or finicky electrical haha. I enjoy the anxiety of both types in my life

[@MatthewFinlay]

Thank you everyone for watching - ya'll are the best! Here's the revival video for this Volvo if you missed it - czcams.com/video/_QUdr3gyGY0/video.html

[@WalterKnox]

My 92 244 has a vacuum leak in the climate control system. It sounds like it is right behind the buttons; there is just a constant hiss nomatter which button you press. All of the blend doors open and close as they should though, and I am lazy, so I just have not done anything with it yet. Whenever I do, all of the little bulbs that light that area up need to be replaced as well, and I am sure other things will pop up (part of why I never want to do anything, one thing turns into 10 on these cars.)

[@MatthewFinlay]

Also here's a written guide that has the climate control vacuum diagram for Volvo 240/240s www.garbagecharged.com/volvo-vacuum-climate-controls.html

[@douglasdowns4846]

"god damn wiring bomb" ha ha ha!

[@MatthewFinlay]

A tsunami of wire!