1996 Chevy Blazer 4WD, I performed a transfer case drain and fill 8 months ago and made sure it was at the perfect level. The other night on my way home the car would not go into overdrive while going down the highway. I pulled over and found the transmission stick barely had any fluid on it. I told myself, "If it's got some fluid in it, it can take me home" my house was a mile away. I got home and unplugged the transfer case and three quarts came out. The vaccum lines were leaking ATF everywhere in the engine bay. So after doing some research I found out that the transfer case input seal causes that issue. So I went ahead and dropped the transfer case out and today I used a good bit of RTV to seal the retainer onto the front of the case. When its cured tomorrow I'll put the double lipped seal in. My question is, I've got vacuum lines that have ATF in them, the HVAC and blend doors are still working. What's the easiest way to get enough ATF out of the spots it needs to be out of without spending all day unplugging vacuum lines and trying to use compressed air on them?

 

Your question is not consistent with the title of the post. I'd suggest reposting a modified version of this with a more appropriate title.

Unfortunately, I have no experience with getting the ATF out of the vacuum lines. Off the top of my head I'd think if they could be removed or at least unplugged so that gravity could drain them would be a start. Then I'd try to find something that would dissolve the ATF but not harm the hoses to flush through the vacuum lines. I'd probably start the flushing until I got some good flow and then plug them for a few minutes so the let the solvent work a bit and then let them drain. I'd flush though with some fresh solvent after that and then let them dry.

I'd hesitate to used compressed air until after the initial flush because you would not want to have to replace the hoses due to them bursting under pressure.

 

If ATF made its way into the vacuum hoses you also likely have a failed vacuum switch on the transfer case. It has o-rings inside that should have prevented the intrusion of fluid from inside the case into the lines.

As far as cleaning the lines, it is a miserable experience for sure. A mild detergent like simple green can be used to remove the residual ATF after a bleed as Christine has suggested. I wouldn't try anything too strong though as some of the lines aren't really solvent friendly.

BTW, I updated the thread title. Please do not create a whole new post over a simple title change.