No air from floor vents in 97

[kyle_in_rure]

Hey all,
97 Expedition with 186K. I've had a problem with my air for the past several months. Whenever I turn the fan to the floor vents it always defaults to defrost, I cannot get the floor vents to blow on any setting. Also, as I turn the temperature knob from cold to warm, air output decreases by a lot out of both the defrost and front vents (whichever it is set to)

Also, sometimes when I am on the highway it will start to switch back and forth between the front vents and the defrost, no matter what the setting is on.


I'm assuming this is a vacuum issue, but I don't really know where to start. I had the dash apart to change dashboard lights a while back but these issues were already happening.

Can anybody tell me where I should start? Thanks

 

[kyle_in_rure]

I just realized I probably shouldve posted in the HVAC forum. I didn't know this site had one....Oh well

 

[BrandonB]

Had something similar to this happen on my monte carlo, was a pesky vaccuum leak on that. Not sure on an expy but probably a good spot to start!

 

[bedrck46]

there was a post a while back about the vacuum controls I'll see if I can find it a send you the link

 

[vigman]

The vac feed from the engine winds up on the pass side behind the battery tray...
Remove the battery cover & the main fuse panel cover ( On the pass side firewall ) will make it easier to see... Mine had a few rotting hoses...Start the engine.. if it's broken you should be able to hear it HIIIIIIIISSSSSSSSSSSSSSSSSSSSing.

 

[BrandonB]

The vac feed from the engine winds up on the pass side behind the battery tray...
Remove the battery cover & the main fuse panel cover ( On the pass side firewall ) will make it easier to see... Mine had a few rotting hoses...Start the engine.. if it's broken you should be able to hear it HIIIIIIIISSSSSSSSSSSSSSSSSSSSing.

That's where mine was - rotted by battery acid. Suffered with only defrost for a couple years until I finally got around to digging!

 

[splintrcel]

it doesnt help that the entire HVAC system is buried under the dash so you cant even see what is moving......

 

[kyle_in_rure]

it doesnt help that the entire HVAC system is buried under the dash so you cant even see what is moving......

I agree. This is why I was hesitant to get involved with it. Just taking the dash apart to change lights was a task in itself.

Ill start looking behind the battery fuses first. Thanks guys.

 

[bedrck46]

behind the battery tray not battery fuses

 

[0xowner]

can this be troubleshot via applying vaccuum via a hand pump (brake bleeder) to the line off of the vaccuum valve under the pass wiper?

that is apply vaccuum to that line run and if it does not hold then either the line is bad from valve to EATC or the EATC unit's solenoids need o-rings?