Question about 2006 Ford Super Duty F 450 Drw

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I have 99 ford F250.The heater is stuck in the defrost mode,have checked vaccum lines all hooked up, check fuse to vacuum pump its ok, any other ideas

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Do you have a source of vacuum? normal problem occurs on the vaccum line from the engine to the vacuum switch of the car. unplug the vacuum hoses from the rear of the switch and feel if there is hose that is sucking your finger. if there is none, then trace the line towards the engine firewall out to the engine compartment. it could be broken that is why it is stuck in defrost mode.

i hope i was able to help.
pls rate me..

Posted on Jul 21, 2008

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Replace the vaccuum pump,pump may run but not be able to pull enough vaccuum.
very common problem with super duty.

Posted on Nov 07, 2008


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