hey everyone, ive been noticing a loss of tranny fluid in my 06 blazer after lookin a while i found it in my reservoir mounted on the hood does this mean the vacuum modulator on the tranny needs replaced or is it something else.

 

This is a clear sign that the vacuum switch on the transfer case is faulty. It is also very likely that the input seal on the transfer case is leaking and has overfilled the transfer case. Check the transfer case fluid level by removing the fill plug on the back of the transfer case. If fluid comes pouring out, then the input seal is at fault.

 

thanks for the help,im gonna check the fluid tonight apparently theres not a vacuum module on the tranny it must be the one on the transfer case.auto zone doesnt show one for the tranny i didnt even think of the transfer case.

 

That is why I never mentioned a vacuum module on the tranny.

 

Autozone has it right on the shelf.. which still surprises me but w/e.. its like a 14 dollar part I believe.

 

This problem is usually a result of the T-case being overheated.

There is a Technical Service Bulletin that addresses it, here's a copy paste of the TSB:



#03-01-38-009: HVAC Mode Switch Inoperative or Stuck in Vent Mode, Oil in HVAC Control Head and/or Vacuum Lines (Replace Transfer Case Vacuum Switch and Contaminated HVAC Components) - (Jun 25, 2003) [/align]
[align=left] [align=left]



Subject:
HVAC Mode Switch Inoperative or Stuck in Vent Mode, Oil in HVAC Control Head and/or Vacuum Lines (Replace Transfer Case Vacuum Switch and Contaminated HVAC Components)[/align][align=left]



Models:
2001-2003 Chevrolet Blazer, S10[/align][align=left]




2001-2003 GMC Sonoma[/align][align=left]




2001 GMC Envoy, Jimmy[/align][align=left]




2001-2003 GMC Jimmy (Export Canada Only)[/align][align=left]




with 4WD and Two-Speed Electric Shift Transfer Case (RPO NP1)[/align]

[hr]

Condition
Some customers may comment that the HVAC mode switch may be inoperative or stuck in the vent mode. After some diagnosis, oil in the HVAC control head and/or vacuum lines may be found.
Cause
When the transmission or transfer case heat up, the oil may expand and find its way into the transfer case vacuum switch. This oil expulsion may cause the vacuum switch seal to fail and allow transfer case oil to be drawn into the HVAC vacuum lines.
Correction
Replace the transfer case vacuum switch. Refer to the Transfer Case Vacuum Switch Replacement procedure in the Transfer Case sub-section of the Service Manual. Also, replace all contaminated parts in the HVAC system.
Parts Information




Part Number

Description


15664811

Switch -Transfer Case Vacuum
Parts are currently available from GMSPO.
Warranty Information
For vehicles repaired under warranty, use:




Labor Operation

Description

Labor Time


K4120

Switch, Vacuum Control Transfer Case - Replace

0.6hr


Add

Diagnosis Time

0-0.3hr


Add

With Skid Plate

0.2hr


Any additional time for replacement of HVAC components must be submitted as Other Labor Hours and requires appropriate authorization.[/align][/align]