Last night after changing the coolant temperature sensor, I noticed a hiss coming from the driver side inside the engine compartment and found this vacuum hose completely deteriorated. can anyone help with where this should connect to and what the hose size is so I can go to autozone and buy a replacement? thanks!

 

I want to say that the one going downward I for the 4x4. Should try it out and see if it's working correctly.

As well as doing a search on here will produce a thread by Christine that has a diagram of the hoses, and how to replace.

 

my blazer is not a 4x4 though. I did find the thread by christine but i couldnt quitw understand it. I need actual pictures.

 

Gotcha. Will look into my 2wd and see what I find

 

Just waiting to pick up the wife, but was thinking... how are your climate controls? Any problems with those? What setup is it?

 

On my 2wd(sonoma, should be the same), it goes into the firewall infront of the driver, under the cruise control module. I'm assuming this is the climate control part of it.

 

If you have a 2wd blazer, the vacuum hoses you have are dedicated to the HVAC system.

There will be one that comes from the top of the driver's side of the engine that is the vacuum supply (RED). It will go into your Tee which also acts as a one-way valve. One of the outputs from the Tee goes to a vacuum reservoir that is located inside the fender and the other connects to the smooth plastic tube that goes through the firewall. (Blue and Orange)

To find the diameter of the tubing you need, you can take a section of the tube you want to replace and cut it where it is not stretched. Then use a drill bit as a go/no-go gauge to identify the inside diameter of the tubing.

On your picture, I've color-coded the hoses so that I can identify them for you.

The red hose is the vacuum supply from the engine.

The blue and orange hoses go to the vacuum reservoir and to the HVAC vacuum line that comes through the firewall. It doesn't matter which goes where.

The key part is that the one-way valve is oriented as it is with the supply coming in on the single port (black end).

The one-way valve only supplies vacuum when the engine is not under load. With the reservoir and one-way valve, the HVAC system actuators can still work even when the engine vacuum is minimal because it will not lose vacuum to the engine, e.g., when driving up a hill or accelerating.


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This is some views from my truck of the reservoir.

Top view looking down. The front of the vehicle is to the left. The ABS system is on the left and the cruise-control module mounted to the firewall is on the left.

• The Red line is the vacuum supply from the top of the engine.
• The Blue line is the line that goes to the vacuum reservoir.
• The Orange line is the one that connects to the HVAC line (the smaller diameter smooth plastic line).
• The line to the 4wd is labeled with brown.

View looking from inside the engine compartment, looking in the outward direction at the inside of the left-front fender. (The circle with an X in it means that is the outward direction, like the fletching on an arrow flying away from you.)

• The line marked in blue is the same one in the previous picture.
• The black panel with the light green lines is the vacuum reservoir.

To get the hose on it, I had to use a mirror and feel for the location of the nipple.

 

There's the vacuum hose expert!!