2000 Ex - V10

Last winter also the front hubs would not lock in when I switched to 4wd. Manually locking the hubs did work.

Now the AC mostly blows out the defrost vents regardless of which switch position I set. Every once in awhile air will flow to the upper vent as desired. I'll hear a flapping sort of sound when it does. After a few mins it will go back to the defrost vents.

Searching here and elsewhere suggests some sort of vacuum issue.

I saw some posts and youtube vidoes re: the vac pump, but those were for diesel; I have gas.

I'm going to have a look tomorrow, but will check here first for any further pointers.

 

Usually the hubs have a vac leak somewhere. Or trash in the line which mine had. I had to blow compressed air through the line to get the dirt out.

 

Or your 4wd vacuum solenoid is bad....mounted on pass innner fender near battery

 

Mine would default to defrost when towing my trailer. Turns out the vacum solenoid was cracked! Very common from whay i've seen!

 

Not sure if this will help...mine is a 7.3 diesel and I went through several things including changing the vacuum reservoir on the advice of the family mechanic......The actual cause of the problem......A loose connector on the passenger battery terminal.....DOH!!!

 

I found the drivers' side 4WD hub vacuum line was broken off at the hub connector. I peeled off the remnants of the line from the connector, and reattached the remaining hose. The connector is fairly rusty. 4WD seems to engage now.

Air does flow to the proper vents as selected now, but sometimes it still does not or does not fully. However, if I engage the 4WD switch, then it fully resolves the air flow to vent issue (until I flip the switch to another vent position or stop/start the engine). Sometimes it works exactly as it should - other times it defaults back to blowing only out the defrost vents, and sometimes it blows a little out the defrost vents and a little to where I have selected.

In all cases -- if the air is not going to where I select it -- I can engage 4WD for a second and that resolves the issue (for awhile).

The short rubber hub vac lines are pretty soft -- I will replace asap. Any other ideas on why engaging 4wd fixes my AC issue and what I can do to fix that?

 

What size is the vacuum hose that runs from the upper wheel well connector down to the axle/hub area? Is that just regular vac house I can get from any auto parts place?

 

have 97 150 an only blows out defrost vent

 

Are you supposed to be able to turn the hubs by hand?

 

Yes you can turn the hubs by hand to "Lock" them or leave them in "Auto" even if you have a vacuum leak and lock the hubs, the vacuum leak will effect the vents from working properly..... nothing but a headache.....

 

passenger side fender, 4wd vacuum solenoid. Unbolt and you will probably find it cracked and rusty on the back side.

 

My02' had a bad vac seal on the left hub...

 

Hmmmm... I can't move mine by hand...

 

2 choices.

Rehab the vacuum system

or

put a vacuum cap on the system and install manual hubs

Had the same thing happen to me, I chose the manual hubs. I was stuck in the beginning of winter and no good way to work on things.

 

I had the problem years ago. It was one of the factory lockouts. I got rid of the factory set and put on a set of Mile Markers. Capped off the vac hoses going to the lockouts. No more vent/lockout issues. I lock the Mile Markers about the end of October and leave there until the end of March.