No air through dash vents

[MerkelG]

Had truck to the dealer twice and they can't fix the problem. Works for an hour on the road then only defroster air and air below the dash. Any ideas... Help

 

[samb]

Gary;

I had this problem and was the control valve that operated the air door in the heating and a/c unit under the dash. The check valve on the vacum pump had disintergrated and had let oil get into the valve. the valve had to be replaced and the check valve.

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97, Lamanie SLT, clubcab, driftwood, 3. 5 spicer 70 rear axle
96 Coachmen Royal 285rk 5th wheel, 11,000 #

 

[dustoff]

there is a TSB and subsequent recall on the vacuum pump check valve for certain year models... . don't recall which years, but would check it out...

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'94 2500 4x4 3:54 auto prime-loc tst #6/230 DiPricol egt/boost

 

[Deezul1]

Had it happen on my 96 and the dealer fixed for free on a recall, I think its #720 but check out Fritz's Rampage it has all the info.
There is no mileage restriction and a 7 year time limit on this recall. Have no idea what truck you have but maybe yours will fall into the right range.
Good luck.

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96 SLT Laramie CC 5spd, 3. 54, no muff, no cat, 5"turn down tip
. Member NRA/USPSA

 

[Andy Morrison]

Just another possibility. The vaccum actuator that moves one of the little doors in the duct work under the dash. Check the linkage fron the dashpot to the lever on the duct door mine has come off twice! Seems that a little bit of the plastic lever has broken off allowing the linkage to slip off sometimes . Have not come up with a permanent fix as of yet . For now I just snap the lever back into place and it works for quite a while . Hope this helps.

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'97 2500 4X4 club cab, BLACK, Leer XL-100,running boards , cup smoothie, EZ Drain, 103,000 miles

 

[F Simkowski (In Memory)]

Moving to the 2nd Gen. forum.

 

[Missouri Mule]

On my Mule one of the vacuum hoses was pinched off it stuck in same mode yours did.
Sorry warranty work don't know if was one comming in to selector switch or going out(toward actuator) believe one coming in. It was inside the cab behind/under the dash.

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Bill Thomas
Missouri Mule - 96 Wht 4X4 ST CC,5 spd, 3. 54, 8 ft bed, 1 ft high cheater boards.
99 Freightliner bl/wht FL60 ISB-5. 9 24v,215 hp,520 tq,6 spd, 3. 59 nsr,16 ft box, 19. 5 tires,Wt/gvw 11,000/23000