hey everyone I am new here so bare with me I bought a 2000 chevy blazer and didn't get to check the 4x4 that good but thought it was working then got to looking up under it a day later changing oil and all the vaccum lines where cut so I then went to trying to figure out where they go the vaccum line to the diafram under the battery u guessed it the line was cut the vaccum line coming from the intake was plugged off idk how I missed that and the lines that are supposed to run over to the hvac and fender wall is gone I have figured out that the line that runs from the diafram runs down to the top of the t case and another one is supposed to run somehow to the canister in the fender and the other one is a vent question I guess I really have is getting my hvac system to work and how to get to the line going to the canister and if it is just a plain Jane vaccum line or is it something else this is my first time dealing with this so hopefully I wrote it up in a way it can be understood I searched many many forums YouTube and no luck what so ever please please help need this fixed by winter and I have to do it myself thanks in advance

 

[QUOTE=Chevyfan757961;680481]hey everyone I am new here so bare with me I bought a 2000 chevy blazer and didn't get to check the 4x4 that good but thought it was working then got to looking up under it a day later changing oil and all the vaccum lines where cut so I then went to trying to figure out where they go the vaccum line to the diafram under the battery u guessed it the line was cut the vaccum line coming from the intake was plugged off idk how I missed that and the lines that are supposed to run over to the hvac and fender wall is gone I have figured out that the line that runs from the diafram runs down to the top of the t case and another one is supposed to run somehow to the canister in the fender and the other one is a vent question I guess I really have is getting my hvac system to work and how to get to the line going to the canister and if it is just a plain Jane vaccum line or is it something else this is my first time dealing with this so hopefully I wrote it up in a way it can be understood I searched many many forums YouTube and no luck what so ever please please help need this fixed by winter and I have to do it myself thanks in advance forgot to add it is the 3 button set up 2 hi 4 hi 4 lo

 

Hopefully this can help
https://www.justanswer.com/chevy/4y3...cture-4wd.html

 

Chuck n truck thank you for fast reply this has helped but the line for the vent there isn't one there how would I find that line and also do u know what size lines go for all of the lines thanks in advance

 

The rubber vacuum lines go soft and gooey with a few years, so you are better off just starting from scratch and replacing all the vacuum lines while you are in there. Using the diagram at the link provided above run 2 lines, one to the vacuum reservoir ("orb") and one to the actuator under the battery. The vacuum source at the orb is usually a line going straight to the intake manifold then tees off a few times around the master cylinder area. One of those tees is the line to the transfer case switch. It doesn't really matter much exactly where you tap in as long as the orb and TFC line are connected without anything except a T between them.

Now, there are actually 2 vent lines. The bigger one comes off the top of the transfer case and vents the case itself. The second smaller line is what allows air into the system to release the actuator when you select 2wd. GM for some weird reason (probably to save 49 cents worth of line) ties the two vent hoses together just above the switch.

This is bad because it is common for the front TFC seal to leak trans fluid into the case, over filling it. Then fluid fills the vent line, in turn filling the switch and getting sucked into the other lines as the switch is cycled. ATF and vacuum lines do not get along!

So I would recommend you run two vent lines up into the engine compartment, one for each component. They terminate in various places for the different years, but most common is simply to the side of the trans dipstick tube an inch or so below the top. A zip tie works well for this. OEM had a fancy fitting with a foam filter on it to prevent insects from entering the line, a piece of open cell foam (lawnmower air filter) wrapped over the end and zip tied in place works the same. In addition to keeping ATF out of the 4X4 system, the separate case vent allows you to spot any ATF exiting, telling you your seal has gone bad.
As for specific size, I did mine years ago and don't remember what I used. I would just take the vacuum switch 3 hose connector with you to the parts store and try the various sizes until you get a good tight fit. You will need most of a full reel. BTW, the TFC vent line is much larger, 1/4" or 3/8".

You might want to consider replacing the switch too if it is old. They tend to stick when dirty and they can leak, allowing the vacuum to suck the TFC fluid into the lines.

 

that was a very good write up slim shady also thank u for the quick reply I am going to go to my local part store tomarrow and pick up a check valve that is recommended for my blazer and start rerouting the lines and I will probley go ahead and go with everything new considering nothing is there but 3 cut lines underneath and zip tied up was like that when I got it I did a manual test just pulling the diafram and it went straight into 4wd which the way I did that was run a line from the diafram to the intake just for a test purpose to make sure nothing was majorly wrong with the t case or anything I am thinking I seen on a fourum those lines are 5/32 but can't be 100% sure if that's right or not wanted to see if someone had been there done that but either way good write up helped me with a better understanding and good vent line tips didn't know that so my understanding is get 2 short peices of line and attach 1 on the t case spot itself and the other on the switch and any recommendations on where to get those lawnmower filters much appricated

 

When u say run a line to the orb are u meaning inside the fender itself and if so is they a easy way to get to it I know it is located on the driver side or do I just run that line from my check valve down to it

 

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Like in this photo it says it runs down to the t case from the check valve

 

 

i went thru today and put all new vaccum lines on and started my blazer and tried to switch the vents and they did nothing and put it in 4 hi and u guessed it nothing pulled the battery so I could watch the diafram and it didn't Suck in even rechecked my work followed diagrams for everything even eyeballed the plug the lines went to and ran lines 1 at a time so I wouldn't get them messed up some how what gives