ATF in Vac Resevoir?!

95 4x4 Blazer with automatic transmission:
Had tranny rebilt last year. Ever since I need to occasionally add some ATF, but none showing up on floor as leak.
Today, while looking for vacuum problem (no reserve vac-AC flaps close when engine under load), I found nearly 4 ounces of ATF in that little round ball vac resevoir that is mounted on the hood, drivers side. The vac line runs from manifold over to drivers side to a check valve where it splits: one leg goes to vac resevoir and the other goes to a T and two small vac lines that disappear into lower area of engine compartment dashboard. I know one of those legs handles the climate control/heater flaps etc.
The question is, of course, how the hell is ATF getting up into the vac resevoir?!?! Could a vac line have been hooked up incorrectly when the tranny was replaced? Where should I look and what should I look for? Also think that the 4wd is not kicking in. Could that be part of the problem or a result of something being hooked up wrong?
I have no vac diagram to work from, so any help the more experienced can provide the better.
Thanks for any direction you can provide.
Gary
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Either the vac. switch on the t-case is hooked up wrong or it just plain failed. Has the AC ever worked right since the tranny was re-built? If so, the switch failed and needs to be replaced, if it hasn't, ask the shop to repair what's broke. They had to remove the t-case to pull the tranny, so they had to unhook the 3 vacuum lines connected to it and then hooked them back up wrong, if the AC never worked right after the re-build.
wrote:

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"Curmudgeon" wrote

The switch in the transfer case is where the ATF is coming from. (the t/case uses atf fluid too) Not real common, but I've seen a few in the shop with this problem. Often, the ATF completely trashes all the vacuum lines inside the vehicle too.
Get a new switch. Also, check the level of the transfer case fluid. If you pull the fill plug on the transfer case and ATF comes spilling out (ie: it appears to be overfull), you probably have a defective front seal on the transfer case. This allows ATF from the transmission to move into the transfer case. Trans fluid level goes down, t/case fluid level goes up.
Ian
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