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Noticed today that the air flow for the air con is coming out of the defrost side of things. Went out and tested what I thought was the vacuum pump, and its dead. Went to Napa, and they cant find the pump, they came up with something that is belt driven. I thought the vacuum pump was the little pump on the passenger side front fendear area that came on when you turned on the key. Is that the vacuum pump? That is what is dead, and has always came on when I was testing for vacuum leaks in the past. Any help on this is so appreciated.
Yep that's the vacuum pump. It doesn't run 24/7, but if you created a vacuum link and started messing with the A/C controls, then it should have kicked on at some point.
A few sites I checked show the belt driven one for our trucks (stupid sites). Is there a Ford part number on the pump? If not, look up FTEPartsGuy on here and send him a PM. He'll be able to help you out.
Here's what I did. I noticed that the elec vacuum pump on our trucks is almost EXACTLY like the one used on some older volkswagon diesels. I snagged about 6 of them from the yard for $5 each and just use one of those when I have to switch out the pump. Can't say I have any left as I gave them to some other superduty guys, but the one I put in my truck was a direct bolt-in and plug-in (once I wired on the right connector), been working perfect for the last 3 years.
Thanks guys for the help. I checked the fuse, and its okay, good check though, thanks. What it was doing before that was running constantly, but not making any vacuum at the pump. I guess it was shot, and finally burned up.
If when you get the new one in it still remains on constantly, plug the line going to the 4-WD solenoid (located above the fender well immediately in front of the pump) and see if it operates properly, i.e. pulls vac and turns off. Not sure what is in that valve, but I had a new one fail after 6 months and maybe a total of 5 actuations.
When I bought my truck it had the same problem. I replaced the pump and found out that the vacuum lines going to the hubs that activate the 4x4 were rotted. You really need to check them. I replaced the lines and the fitting that goes down by the hubs. No more problems. Good luck.
I replaced the lines that go down to the 4x4 last year thinking that they were probably getting bad. I have been having problems getting it to go into 4x4 though. Transfer case goes in, but hubs wont stay in. I wonder if the 4x4 vacuum canister is bad also? If you turn the 4x4 switch ,you can hear the transfer case click in, and I verified that it is actually going in all the way correctly, and you can hear the hubs click also, but shortly after the vacuum pump would come on, air would switch to the defrost, and the hubs would never actually be in 4x4.
I replaced the lines that go down to the 4x4 last year thinking that they were probably getting bad. I have been having problems getting it to go into 4x4 though. Transfer case goes in, but hubs wont stay in. I wonder if the 4x4 vacuum canister is bad also? If you turn the 4x4 switch ,you can hear the transfer case click in, and I verified that it is actually going in all the way correctly, and you can hear the hubs click also, but shortly after the vacuum pump would come on, air would switch to the defrost, and the hubs would never actually be in 4x4.
I just went through mine on the passenger side. There is a seal behind the hub assembly that probably is bad. I checked vacuum readings at several places and found that I was losing most mine at the passenger hub. Replaced all the seals and lines. I should have bought the oring kit for the hubs themselves but didn't. Anyway after a days worth of work chasing leaks here and there, it now appears to be working as intended. I have caps on my rims and like the way it looks. Due to this I really need the auto hubs to work correctly. Especially since winter weather will be here soon enough.
i think my pump may be going bad too. i have a (don't laugh) womp womp womp noise when i am sitting there idling with the brake on thats coming from the passenger side of the engine bay. its worse sometimes with the A/C on but am trying to figure out what it could be. only thing i could thin of would be the vacuum pump. anyone else heard/had this happen before? only noticeable at extremely low speeds (e.g. turning in and out of the driveway, idling at a stoplight, fast food drive thru, etc...). Seems it is definitely coming from the passenger side of engine bay. any help would be appreciated.