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Oct 19, 2009 | 06:30 PM

bigfordmatt

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heater

so heres my problem i did some custom work to my dash and had it all out and it worked fine then but when i put it back in i only have defrost no air comes out any vents other than the deforst ports any ideals???

Oct 19, 2009 | 07:20 PM

F350-6

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From: Texas

Sounds like a vacuum leak. Did you get all the little colored hoses plugged back in nice and tight? A vacuum leak will cause the air to default to defrost.

Oct 19, 2009 | 08:24 PM

bigfordmatt

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yeah there pluged in tight as they were to begin with but when i unpluged them the first time i heard like a sucking noise coming from the plug for a sec then that was it so now what u think i might have a hose pinched or something like that??

Oct 19, 2009 | 08:38 PM

F350-6

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From: Texas

Usually the defrost thing signifies a leak. Turn your key on (not start) and listen to how long the vacuum pump runs. Do this several times in a row. If the pump can't build and maintain pressure, you've got a leak somewhere.

Maybe the dash work is just a coincidence, so be sure and check out all the vacuum system. A leak at the 4x4 autolock hubs can cause the same defrost issue.

Oct 19, 2009 | 09:02 PM

bigfordmatt

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so were is the vacum pump at and i have the manual hubs on it

Oct 21, 2009 | 06:43 PM

bigfordmatt

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fixed the problem i had a blwon fuse

Dec 10, 2009 | 12:13 PM

hunter101

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Which fuse did you find that was blown? I have the same issue where my heater only blows at the defrost mode.

Thanks

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Dec 11, 2009 | 02:37 PM

bigfordmatt

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its was a 20 amp fuse i think its under the dash, or it might have been under the hood. just take a test light to the vacuum pump on the passenger fender to see if its the fuse or the vacuum pump. then just go trough the fuses and find the blown one, unless u have the manual that tells you what they goto. i think its might be labeled as 4wd vacuum pump or something stupid like that. i just hocked a test light to ground and went across the fuses and found a blown one and replaced it instead of looking for which one it suppose to be.