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Vacuum operation of control

MR WIZARD's Avatar
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Join Date: Mar 2018
Posts: 1

March 11th, 2018, 1:51 PM   #1  
Vacuum operation of control

My g30 only has a defrost outlet center vents..any helpful time saving tips before removing the dash? Thanks

mountainmanjoe's Avatar
CF Junior Member

Join Date: Feb 2017
Posts: 93

March 11th, 2018, 2:09 PM   #2  
Haha Mr Wizard. Like the name.
Probably a rotted out vacuum line. Have a gander under the hood.

StanVan's Avatar
CF Senior Member

Join Date: Jul 2008
Posts: 536
Fairfax Virginia

March 11th, 2018, 3:51 PM   #3  
When HVAC in a car looses vacuum, it will revert to defrost.

jimmyblue's Avatar
CF Beginner

Join Date: Jun 2014
Posts: 11

March 15th, 2018, 10:08 AM   #4  
On my '02 1500 Express I found the soft line from the "T"
to the reservoir ball had fallen off due to the end splitting.
This is accessible from the hood, right next to the battery.

Dunno how or whether newer / older are much different -
G30, what year & motor?

At that same "T" you could check motor vacuum and if
none, check the other end of the "hard" (plastic) line to
the manifold vacuum port; if attached there and no far
end vacuum, suspect plastic line cracking and replace
with a full run of rubber vac hose.

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