AC issue.....
Elder User
Joined: Oct 2014
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From: CT
If the cold air is only coming out of your Defroster vents then, you've most likely got a vacuum leak (or leaks). The blend door allows the air to shift between the various vents. It's operated off of engine vacuum. The default state of the blend door if there's not enough vacuum getting to it is to stay in Defrost.
I had an '95 F150 5.0L that had a bunch of small vacuum leaks when the hoses got old and brittle. If you had the A/C on and stomped on the throttle, the airflow would switch all by itself from the vent to the defrost. When I let up on the gas, and the engine built up some vacuum, it would shift back to the dashboard vents. I ended up changing all of the vacuum lines - truck ran much better, and the AC came out where it was supposed to.
A common vacuum leak culprit is the 4x4 shift on the fly, auto hubs - the vacuum lines either fall off, or rot out.
I had an '95 F150 5.0L that had a bunch of small vacuum leaks when the hoses got old and brittle. If you had the A/C on and stomped on the throttle, the airflow would switch all by itself from the vent to the defrost. When I let up on the gas, and the engine built up some vacuum, it would shift back to the dashboard vents. I ended up changing all of the vacuum lines - truck ran much better, and the AC came out where it was supposed to.
A common vacuum leak culprit is the 4x4 shift on the fly, auto hubs - the vacuum lines either fall off, or rot out.
Hotshot
Joined: Jan 2004
Posts: 19,768
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From: St Louis
The blend door allows the air to shift between the various vents.
It's operated off of engine vacuum.
The default state of the blend door if there's not enough vacuum getting to it is to stay in Defrost.
You can hear it blowing but nothing come out of the AC vents.
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Cargo Master
Joined: Aug 2004
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From: Williams Lake B.C.
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Cargo Master
Joined: Aug 2004
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From: Williams Lake B.C.
You lost me badly somewhere?
What makes the heater go from defrost to AC?
Theres a electric motor that blocks one or another off?
Or is it vacuum operated?
It worked fine until I changed 4x4 thing under the hood.
The air blows out of the defrost when on AC.
What makes the heater go from defrost to AC?
Theres a electric motor that blocks one or another off?
Or is it vacuum operated?
It worked fine until I changed 4x4 thing under the hood.
The air blows out of the defrost when on AC.
Elder User
Joined: Oct 2014
Posts: 607
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From: CT
The Diverter door works on vacuum. Without sufficient vacuum it only works (by design) in defrost mode.
So did you disconnect a vacuum line (or lines) when you changed out the "4x4 thing under the hood?"
So did you disconnect a vacuum line (or lines) when you changed out the "4x4 thing under the hood?"
Hotshot
Joined: Jan 2004
Posts: 19,768
Likes: 1,082
From: St Louis
The air blows out of the defrost when on AC.
Either your vacuum pump isn't working or you managed to introduce a new vacuum leak into the system by accident when you replaced whatever it was you replaced.
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Cargo Master
Joined: Aug 2004
Posts: 3,455
Likes: 8
From: Williams Lake B.C.
Thank you. Now that you've provided specific answers to specific questions, it can be determined that you do indeed have a vacuum issue (as explained by RightWingNutJob).
Either your vacuum pump isn't working or you managed to introduce a new vacuum leak into the system by accident when you replaced whatever it was you replaced.
Either your vacuum pump isn't working or you managed to introduce a new vacuum leak into the system by accident when you replaced whatever it was you replaced.
Thank you thank you ................
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Cargo Master
Joined: Aug 2004
Posts: 3,455
Likes: 8
From: Williams Lake B.C.
Thank you. Now that you've provided specific answers to specific questions, it can be determined that you do indeed have a vacuum issue (as explained by RightWingNutJob).
Either your vacuum pump isn't working or you managed to introduce a new vacuum leak into the system by accident when you replaced whatever it was you replaced.
Either your vacuum pump isn't working or you managed to introduce a new vacuum leak into the system by accident when you replaced whatever it was you replaced.
On my 02 my vacuum lines havnt worked to my hubs for years but my AC still worked?
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