I thought I'd post an issue here before I waste time, and perhaps parts, chasing down the wrong path. We've got an 01 7.3 with almost 290,000 miles on her. Over the years we've had to replace this or that and now I'm having an issue with the A/C.

In previous years the A/C in this Excursion would cool so well when set to Max A/C that you could hang meat in it. (We actually keep blankets in the back for those that can't take it.) Near the end of last summer when we'd switch the A/C on, it would work just fine, but when switched to Max A/C the system would switch the outflow from the dash outlets to the defrost outlets. But this only happened when switched to Max A/C, so we didn't address it at that time. We've lived with this issue this summer, but I'm ready to find and fix the problem.

I suspect that this is a vacuum related issue. I know that the "auto" hubs are not engaging and have been locking them in manually when I think we'll need 4-wheel drive. And I know that this is a vacuum actuated feature. So my thoughts are that the two are related, and if I can find and resolve the vacuum problem that I know is affecting the hubs, then I just might also resolve the Max A/C issue.

What do you, the experts, think of this A/C problem? What are your suggestions to a guy that likes to DIY with the tools available in a modest garage? I have no gauges or meters with which to measure vacuum.

Your input will be greatly appreciated. And now I'll start another post for some other, non-related questions.

 

Howzit! This is an extremely common problem. You should be able to easily locate the fix via a search.*

You are on the right track! It's a vacuum problem and easily fixable!























* I can't remember the exact steps you need to take right now so I copped out.

 

It's usually a bad vacuum hose to the hubs which allows crap to enter the system which also takes out the hub seals and ESOF solenoid, when this happens the HVAC defaults to defrost.

 

See? My copping out paid off. You got the correct answer!


Yup, you is on the right track! Carry on!

 

Subscribed.... I have the same exact problem and I live in Florida so showing up to business meetings drrenched isnt a good thing....

 

Thanks Shepherd2 and Monsta. This weekend I'll check the vacuum lines from the hubs to the ESOF system. I may just cap off both the lines and the ports they go onto and make my hubs totally manual. Then I should know if the ESOF pump and/or reservoir are good to go and able to properly run my HVAC system.

 

I had the time, so I popped the hood this evening before it got too dark to see. I found that the vacuum line going to the heater control valve, just before the firewall, had broke about 6" from the valve. I capped it off and the Max A/C worked just fine. I haven't checked the function of the hubs, but I'm assuming they will also work as designed.

Now I have to decide whether I want to repair/replace the vacuum line to the heater control valve, or replace it with a simple, yet manual valve of some sort.

Thanks again for the input I received to this posting.

 

Awesome! A follow up with the root cause! REPS TO YOU!

 

Mine has issues as well. The max blows the same as ac. I can get in and turn it to max and it will not blow out of vents at all. Then switch it to ac and it blows out of vents switch it over to max and it blows out the vents the same as ac. Not that I know what I am looking at but I will check for vacuum leaks.

 

Where does it come out then? Might be electrical instead...like the switch.

 

Do you ever get this fixed. I have the same issue and mine is related to a broken,

HVAC Heater Mode Door Lever - Ford (F81Z-18K542-AA)

I am having a hard time get a quick replacement without $10 dollar shipping charge. I have glued the broken part but am having a hard time reinstalling. Not sure if any has some tips & tricks or picture of the process of replacing that level on a 2002 ford excursion.