Hello all..... Proud new owner of a 2001 7.3....today.

Been reading but can't quite get answer to this:

The previous owner installed Warn standard hubs. I assume they work same as OEM with the exception that I have to get out and lock them, right?

Also, when I test drove it, and after locking them, I engaged to 4x4 button and the 4x4 engaged and worked. However, when I disengaged my AC went to defrost just like my old 7.3. The AC eventually came back. Is this normal? I think it also went to defrost when I engaged. The AC does come back after a couple minutes after disengaging.

Any advice on this would be appreciated.

Thanks, Jed

 

Sounds like the previous owner did not plug off or address the vacuum lines. Take a look around each wheel well for a loose or damaged vacuum line and check under the hood to see if is blocked off at the vacuum pump. It should be.

When there is a vacuum leak our hvac systems default to defrost.

Also, make sure the stubs where the vacuum lines go into each hub are blocked off to prevent entry of dirt or water.

By the way, congratulations on your purchase!

 

Thanks. About to go outside and check it.

 

Looks like all hoses are connected. Vacuum pump for sure. Dark out so looking around tires a little hard. So, if they are all connected how should I fix this? If the hoses are blocked off, how would the shift button work to engage? How do they differ from OEO engagement? Sorry.... Just don't quite understand how the after market hubs work.

 

Or does the Warn hubs bypass the shift button when I lock them in manually no matter if it's on 2x4 or 4x4?

 

Warn does make auto locking hubs also. I'm not sure if they make one for the Super Duty, but it might be a good idea to look into that aspect.

 

if your ok with manual locking hubs,just cap off vacume at pump then your esof switch on the dash shifts your transfercase & your hubs engage your front axle shafts,two separate events with manual Warns,you also have the option to shift in low range 2x4.

 

I think I'm over thinking this..... Let me get this straight: to activate my 4x4 with standard warns, with vacuum lines still connected, I have to lock them in manually and then turn the 4x4 button on dash to 4x4, correct? The dash button has to be turned to engage axle right?

 

dash button shifts the transfercase & signals for vacuum to engage auto lock hubs ,but with manual Warn hubs the vacuum is not needed,so you have to get out & manually engage or lock your hubs,if your sending vacuum to front axle your increasing a chance for a vacuum leak which will default system to defrost.

 

Got it. I understand now. Thanks for explaining. So, since I have Warns, I need to plug my vacuum lines (like I was told above) and all will work fine with no defrost kicking in.

Thanks to all who responded

Jed

 

If I can bother you guys one more time.....

I think I've found my problem but wanted to post a couple photos first to confirm before I try to fix. To recap, I have Warn hubs and cannot find where the vacuum lines are blocked off by previous owner. I'm getting defrost when I start it up and turn the SOTF button.

So, following suggestions here, I traced the vacuum lines and found that both sides of tires have dry rotted vacuum lines. See the photos to confirm they are right vacuum lines. So, I assume this is my problem but I don't understand how I'm getting any dash AC with the lines completely gone like that.

If I block off the vacuum lines at vacuum pump, will this fix the problem? Will my AC work with that line blocked ?

Thanks again

 

Another pic

 

Or should I block them off at pump?

 

Block the line off at the pump. Once the line is blocked you can remove the vac lines as one will run straight down to the front right and the other line runs across above the front axle and then up and over to the drivers side. It's actually one line that splits about 6-12 inches from where you cap it off. I pulled off the entire harness and tossed it.

 

I would block it up at the pump, where the line goes out to each wheel and not have to worry about that vacuum line. Just make sure that where it goes into the axle hub is blocked off so that it won't get contaminated from the outside elements.

Basically whats going on is when the system detects a leak the vents will automatically go to defrost for safety to prevent your windshield from fogging up. The only thing that is vacuumed related on these trucks is the Auto 4X4 and the climate control system.

Usually the leak will occur in the hub where there is a yellow O-ring, and they tend to fail. I'm assuming thats why the previous owner went with the Warns, so he had working 4X4.

Hope that helps and if still confused fill free to ask.