HVAC question

BigBlockRanger · Apr 30, 2008

I searched, but didn't come up with an answer?

Cruise control ON
A\C ON

You start up a hill and the HVAC doors switch to the defrost position, and then once you clear the hill they return to their original position.

Is this a common problem with these trucks? I have noticed it'll only do it when the cruise is on, so I assume it's a vacuum leak somewhere in the cruise control.

My 98 has done this for a while, which isn't really all that annoying because we live in a relatively flat area and I drive about 3 miles to work everyday.

thanks,
James

Duranged408 · Apr 30, 2008

I'd say yes, you have a vacuum leak somewheres. The fun part is finding it, someone should chime in soon to help you a little more.

Edit** Also, the leak could be in any of the vacuum lines so don't rule out other circuits.

DCDAD · Apr 30, 2008

BBR,

x2 on the vaccuum leak, probably one of the plastic tubes under the hood., that's where I'd start as they tend too get brittle over time and crack or break completely when disturbed. happy hunting!

Ron

FSTDANGO3 · Apr 30, 2008

Definitely a loss of vacuum
Steve
DOC Pres

BigBlockRanger · Apr 30, 2008

Ya know, I was really hoping one of you'd say:

"Yeah, it's the little line that runs from X to X, they crack all the time"

Happy hunting it'll be I suppose. :mrgreen:

tomk · Apr 30, 2008

also possibly a bad vacuum reservoir? I forget where it's (or if it even exists) in the early gen-Is?

(later gen-Is use electric controls and I suspect they don't have a reservoir?)

FSTDANGO3 · Apr 30, 2008

One of the little hoses that runs from a to b or c to f or h to g must be cracked, There ya have it lol
J/k I hate witch Hnts myself
Steve
DOC Pres

Duranged408 · Apr 30, 2008

tomk said:
also possibly a bad vacuum reservoir? I forget where it's (or if it even exists) in the early gen-Is?

(later gen-Is use electric controls and I suspect they don't have a reservoir?)

My 99d's reservior is located passenger side under the wiper cowl

One of the little hoses that runs from a to b or c to f or h to g must be cracked, There ya have it lol
J/k I hate witch Hnts myself
Steve

Witch hunts, is that when you break out the carb cleaner?
(In my instance making sure to have a candle/match/& lighter in my other hand)

BigBlockRanger · Apr 30, 2008

Duranged408 is dat you?

:?

FSTDANGO3 · May 1, 2008

Duranged408 said:
tomk said:

also possibly a bad vacuum reservoir? I forget where it's (or if it even exists) in the early gen-Is?

(later gen-Is use electric controls and I suspect they don't have a reservoir?)

Click to expand...

My 99d's reservior is located passenger side under the wiper cowl

One of the little hoses that runs from a to b or c to f or h to g must be cracked, There ya have it lol
J/k I hate witch Hnts myself
Steve

Click to expand...

Witch hunts, is that when you break out the carb cleaner?
(In my instance making sure to have a candle/match/& lighter in my other hand)

Nothing like finding an intake leak with can of carb cleaner
Steve
DOC Pres

Duranged408 · May 1, 2008

BigBlockRanger said:
Duranged408 is dat you?
:?

Close, but this would most likely be the outcome. :cheesy:

qwassy111 · May 1, 2008

Duranged408 said:
I'd say yes, you have a vacuum leak somewheres. The fun part is finding it, someone should chime in soon to help you a little more.

Edit** Also, the leak could be in any of the vacuum lines so don't rule out other circuits.

I had the same problem during a scorching Florida summer a few years back. The control was stuck in floor mode. I was lucky enough to have fixed under the 36k mile warranty at that time. Other than that don't know much about it other than it required a lot of work and wouldn't be cheap out of warranty. Have to take the whole dash apart on this one.

HVAC question

BigBlockRanger

Duranged408

DCDAD

FSTDANGO3

BigBlockRanger

tomk

FSTDANGO3

Duranged408

BigBlockRanger

FSTDANGO3

Duranged408

qwassy111

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