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OK, I'm looking to tackle my last issue with my EX which is a vacuum leak. I'm almost sure the leak is near one of my hubs but I'm not sure as of yet. I have never changed these before and looking for some insight from someone who has had this trouble and solved it.
Symptoms:
When I run my air in my truck (heat or AC) and select floor, head or defrost positions the air alternates from the defrost vents to the head vents based on how fast I drive. I was told that this was a sure case of leaking vacuum hose / hoses. I'm looking to solve this as soon as I can.
Concern:
Can the you put the EX in 4X4 by the selector switch on the dash? In my mind I thought that it would use the vacuum to engage the hubs to lock in. Right now I think I can only manually lock them in place for it to work. I'm coming from a Escalade ESV before my EX so I'm not that familiar...
Ok, just replaced vacuum hoses on both front wheel hubs. They were out of the then vacuum hose I needed so I used the 3/16" fuel line hose instead. The fuel line seems a little more heavy duty compared to the little vac hose, and the fuel line fits through the vacuum hose holder loops with no problem. Anyway now when I turn my heat to the floor it comes out of the floor vents. It never use to before, only out of the defrost and head positions. After test driving I notice once my transmission changes gears the heat vent goes from floor to defrost position. When I slow back down it goes back to the floor. I tried to engage my 4X4 to see if I could tell the difference and I really can't say. It kind of seems like it had more power on the take off but it did not feel any different turning corners. Not sure what it should feel like with the Haida 33x12.5x20 tires. The vacuum lines seem to be ok under the hood. I guess I can check my vacuum reservoir... Any suggestions would be appreciated.
Check the 2 lines at the hub solenoid on the rf fender. Ours had a crack in the 90 deg rubber connector under the solenoid. Other than that, check all vac hoses since you've already covered the hub lines.
A leak in the vacuum lines to the hublocks can affect the HVAC system ONLY during the act of switching, otherwise, those lines aren't in the vacuum circuit.
A leaking PVH solenoid is a common problem, I've had it on my 01 SD. Cap off the vacuum line to it so as to isolate that circuit from the rest of the vacuum system.
Check the supply line that runs from the engine compartment to the HVAC control head. It gets exposed to all kinds of nasty fumes in the vicinity of the battery and cracks.
If you have the EATC control head, those have rubber O-rings that wear out and leak.
