School me on vacuum pumps

[yellowhorse7]

Okay, first a bit of history. 2006 F350 DRW. Last fall/winter I had a squirrel problem...they made a nest on top of the passenger side battery. Little bastards managed to chew thru the ac wiring, both vacuum lines that run to the pump and a few other wires. I found it, cleaned everything out and repaired all. Things were fine until a few months ago when I discovered the 4x4 wouldn't shift on the fly. Turned out they got in there again and got the vacuum line AGAIN! I got it fixed and all was good. Well yet another came back and got to the vacuum lines again (same ones). I repaired and all was good

Now, here's the issue. I went to work the other day and everything was good. Jumped back in the truck and the climate control defaulted to defrost and would not change. While I was looking for another vacuum leak I discovered that the vacuum pump would not shut off. A few days go by and now everything works fine as I have both 4x4 and full climate control. But the pump will run for 2 minutes, cycle off and pulse, then run continuously again, all while everything is working fine. I assumed that they were only supposed to run to build vacuum into the canister and then shut off, only to cycle on /off as needed. What is the proper procedure for these things?? Help as I am at my wits end with this issue.

PS....still working with trying to get rid of the squirrels!!!

[bismic]

You assume correctly on the operation. Three common places for vacuum leaks - 4WD hubs, heater flow control valve (heater hose by the firewall), blend door (behind the glovebox).

[fordmasterdieseltech]

yeah the control valve for the heater is super common. they fall off if the wind blows to hard to the east on a cold day in april.. lol j/k they dont fit worth a damn, if you find it off, replace the end with a unit from ford. fits better and shouldnt be an issue again.

[bismic]

Originally Posted by fordmasterdieseltech

yeah the control valve for the heater is super common. they fall off if the wind blows to hard to the east on a cold day in april.. lol j/k they dont fit worth a damn, if you find it off, replace the end with a unit from ford. fits better and shouldnt be an issue again.

Great to know. Thanks for the info!

[Davey~do]

Sounds like you might want to look into some kind of braided hose wlhere those boogers like to nest up!

Wonder if something like STAINLESS STEEL BRAIDED would work?

[yellowhorse7]

Thanks guys, I'll check the heater control valve. But why would it be working now? It went from working to not working back to working. Any ideas? I wouldn't think a vacuum leak would be intermitent.

[Fordpowerstroke350]

I would be having squirrel stew to solve the problem