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Apr 20, 2014 | 09:56 AM

sams6.9

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From: HALLSVILLE TEXAS

possibly a dumb question

On my 06 f350 4wd, when the hubs are in auto they will not engage but flip them to lock and they work fine. ive looked and cannot find anything unplugged or out of the ordinary.

Apr 20, 2014 | 09:58 AM

MisterCMK

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From: Blue Hill Township

When you switch to 4x4, does the air blow out of the defrost?

Sent from my Telegraph using IB AutoGroup

Apr 20, 2014 | 10:00 AM

jswartz84

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From: Roseburg, OR

Either the hub needs cleaned up or you have a vacuum leak.

Apr 20, 2014 | 10:01 AM

Jmoen7

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Joined: Oct 2012

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From: Ontario

That will be a vacuum issue, 99%. Hubs are most likely just fine. Engage the auto mode and answer the above question

Apr 20, 2014 | 04:18 PM

sams6.9

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From: HALLSVILLE TEXAS

No the ac doesn't change where it blows out.

Apr 20, 2014 | 04:28 PM

Skiddy 1

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4wd actuator is bad. It is controlled by vacuum. Had same problem on my 04 6.0. Both hubs would lock manually but not with the switch in the cab. I did however have the problem with air switching from defrost to vent with acceleration.

Apr 20, 2014 | 04:39 PM

MisterCMK

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From: Blue Hill Township

Quote:

Originally Posted by sams6.9

No the ac doesn't change where it blows out.

Do you have a handheld vacuum pump that you can test with?

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Apr 20, 2014 | 04:59 PM

MisterCMK

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From: Blue Hill Township

It is not necessarily the actuator. Do you have vacuum from the pump?

Apr 20, 2014 | 05:03 PM

#10

sams6.9

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From: HALLSVILLE TEXAS

Yes I have vacuum from the pump I tried bypassing the actuator just a min ago an they lock in.

Apr 20, 2014 | 08:32 PM

#11

steelhead2

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I had a relay issue one time that wouldnt allow them to unlock. I switched the 4x4 switch a couple times and it started working again. If i recall the relay was by the vacuum pump.

Apr 23, 2014 | 07:23 PM

#12

holdtyte

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Joined: Apr 2008

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I have had my passenger side vacuum hose come off twice causing the same issue. I would follow the small tubing from the hub up to the connections by the cross member. The "Tee" connection is as strong as I would have thought. Lats time it happened I stuck it back on and used a little heat shrink to keep it there. Been fine ever since.