Spirit only blows on floor or defrost

[Sethyboy85]

It slowly stopped working and I used to get a whine noise under the dash in boost and it would go to defrost if it was on vent.
now no there is no whine noise and ONLY floor or defrost.
I looked under the dash everything seems connected and have replaced the hvac unit and nothing changed.

[wheming]

The whine noise under boost is because there is a check valve under the Hood that is bad.
Find the tiny plastic line that goes through the firewall for the hvac, and trace it to the vacuum source. There should be a check valve in part of that line. Remove it and test the check valve to see if it is bad.

As to the other problem, while you are tracing that tiny plastic line, look for cracks or breaks. They get brittle over time and split and break.

I added a vacuum resovior to my Dodge to help maintain the vacuum to certain things under boost, hvac, and cruise.

[Sethyboy85]

well the only thing I see is right off the brake booster and it's big, then the line goes to a round thingy and thats where the hvac lines run from to the hvac unit.
So replacing the big check valve by the booster should help with the situation?

[wheming]

You can test it to make sure.
Pop it out and see if it checks. But yes that is supposed to prevent boost from getting to the hvac.

[Sethyboy85]

oh yeah totally shot check valve, I had a extra one on a line I had plugged coming off my cruise control. Not sure why it was there but since my CC works I just moved my plug to behind the check valve and swapped it to the line that runs into firewall. Now to check that line and see if it's cracked or if the round thingy under my dash is busted that has lines running the hvac, I feel this is a JY part... also looks to be a HUGE pain to remove.

[Sethyboy85]

Pulled the black round thing with 2 lines from HVAC unit running to it. The plastic piece on end (assuming mix door) is broken and that's probably why it stopped being able to switch between vent and anything. Now the hard part is finding a replacement and then figuring out how to install since mine just fell down when I undid the bolts

[wheming]

Boost to it probably didn't help it.
Sorry. Hope you get it fixed.

[Sethyboy85]

this piece the plastic white on end

[wheming]

Maybe someone has that from a parts car, or you might have to go junkyarding.

You mean that clip, or the end of the arm is broke?

[TopDollar69]

I have a spare one, but they are a pain to replace. If you want to do it correctly the whole dash and heater box need to come out. I have had success cutting the heater box with a Dremel Tool and JB welding the top piece back in place once I replaced the inner part.