Vacuum leak and no 4X4 LOW

[04FordF250FX4]

Hello all,
Just bought an 04 FX4 and it has a few problems. I think it has a slow leak in the vacuum lines because after I shut it off when I restart the A/C blows out of the defrost for a while then out of the dash. Also I do not have 4 low I was told this could be caused by the vacuum leak. Any Ideas how I can track down the leak?

Thanks a bunch.

[SteveM63]

Here's you a bump And I'm going to be watching this because I have an 05 with exactly the same problem and have been wondering how to track the leak myself.
Steve

[fallendown]

Mine was doing the same thing . It was a small vacuum solenoid behind the passenger side battery on the fenderwall. If you trace the lines on it they run to the front hubs. Was $64 from the dealer. Instant engagement of 4WD now, used to take forever for the hubs to lock, air blew through the defrost vents for a long long time. Hope this helps.

[Drepka]

Yeah the pump is out or the canister is cracked........could be your lines too, mine were dry rotted and I had to replace them. Next time your ac is blowing through the defrost get out and tap on the vacuum pump right behind your passenger battery. Thats what i did to mine and it worked.

[04FordF250FX4]

Thanks guys I will check the pump behind the passenger bat.

[twoicebergs]

I would agree with the A/C, but the 4x4 low issue is not usually a vacumn fault. Vacumn is only used to lock the hubs and enable the 4wd solenoid. So if your truck goes into 4hi, then 4Lo is achieved by maintaining the hubs locked signal, and by the neutral and brake on sense giving the pass signal to enable the Low solenoid.

[fallendown]

True, you have to allready be in 4WD, then put the truck in neutral with your foot on the brake, then engage 4LO.

The sacrifice of a live chicken may also help.

[04FordF250FX4]

twoicebergs, fallendown.
it is quite possible that I was not engaging the 4 low correctly I stopped and just turned the knob to low I did not put it in neutral. My 2000 F250 had the manual 4x4 not the knob.

Thanks I will try it.

PS would a goat sacrifice work I have plenty of those.

[04FordF250FX4]

I have 4X4 low I just needed to put the truck in neutral then flip the switch to 4 low. I need to get a book for this thing.

Thanks to all for the help.

[fallendown]

Originally Posted by 04FordF250FX4

twoicebergs, fallendown.
it is quite possible that I was not engaging the 4 low correctly I stopped and just turned the knob to low I did not put it in neutral. My 2000 F250 had the manual 4x4 not the knob.

Thanks I will try it.

PS would a goat sacrifice work I have plenty of those.

MMmmmmmm.....Cabbrito......