HVAC defrost only - Ford Powerstroke Diesel Forum
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post #1 of 7 Old 01-05-2014, 06:00 PM Thread Starter
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HVAC defrost only

So my issue seems to be pretty common. The HVAC system works fine with temperature and fan strength, but it only blows out of the defrost vents. I have read several threads on this topic, and checked out the vacuum system. It all appears to be fine. I can hear the pump turning on when I crank it up. It stays no more than a minute longer than fuel pump then shuts off. I unhooked the two lines from the vacuum reservoir and tested them to see if they held the pressure. Both held it fine, to my surprise according to the threads I have read.

With all this in mind, what suggestions do yall have for me?

I'm still new to this forum, so if this is not in the correct section of the forum, please move it or let me know.
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post #2 of 7 Old 01-05-2014, 06:03 PM
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drop your glove box past the normal hold open position by pressing the retainer

there you will find the vent actuator u can manipulate it by hand and watch it when u select different vent options to see if it tries to move

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post #3 of 7 Old 01-05-2014, 06:05 PM
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Pull your glove box out and check the vacuum actuator that operates the doors that changes where the air goes. If that is working make sure all the linkage is hooked up and that the doors are opening and closing and are intact.

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post #4 of 7 Old 01-20-2014, 06:50 PM
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Check the vacuum pump out on the inside of the right inner fender. It should kick on with the key on then turn off within a min so. I had one where the hose was unplugged.

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post #5 of 7 Old 01-21-2014, 10:18 AM
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Mine does that when I switch into 4wd. But I know I have a vacuum leak somewhere between the pump and the hubs that I haven't found yet. When I turn off my 4wd, it goes back to normal (def/floor or vent/floor).

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post #6 of 7 Old 01-22-2014, 06:47 PM
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mine has a weird situation, kind of like yours, but mine will change.

i'll warm the truck up in the morning on defrost, and when I get in the truck and change it to vent and floor it will only stay on defrost, I have to press it to vent then wait for it to blow out the vents before pushing the vent&floor button.

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post #7 of 7 Old 01-29-2014, 08:20 PM
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When I had the problem my vacuum line right next to the oil fill cap kept coming off and I had to reziptie the route.

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air conditioning , hvac , vacuum

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