everything comes through defroster
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Freshman User
Joined: Jul 2003
Posts: 25
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everything comes through defroster
I have a f250 7.3L diesel. Recently all my heat and air conditioning only come through the defroster. The heat and air conditioner work, they just come through the defroster. Has anyone experienced this? Any help or suggestions. Thanks
Senior User
Joined: Apr 2002
Posts: 211
Likes: 0
From: Reno USA
everything comes through defroster
I had a similar problem on my 01 F-350. It turned out to be a vacume line that had come disconnected. Look around under the hood and see if that might be your problem as well.
Cross-Country
Joined: Dec 2002
Posts: 73
Likes: 9
From: glendale us
everything comes through defroster
Ranlyn54,
I'm having exactly the same problem with my 2000 4X4. Mine is intermittent. I've noticed that it almost always happens when I'm in the desert (100+ degrees) and is often triggered by putting the truck in 4 wheel drive. After 1-6 hours, it usually corrects itself. I've come to a couple of conclusions so far: 1. The vacuum pressure is lost before the line enters the cab. 2. It is being affected by the vacuum actuated auto-locking front hubs. 3. The 4X4 mechanism is very slow to engage sometimes. 4. The Powerstroke has a seperate vacuum pump, rather than a conventional vacuum system on a gas engine.
I think that either the vacuum pump has a problem, or there is a leak somewhere in the vacuum system. I'll try to pin it down and post my fix (if I find one). I've fixed this defroster-only problem on my Mustang and F-150. It was a very simple fix on both. Usually the vacuum lines dry-rot or become brittle and break after five years or so. The break can usually be fixed with some cheap, rubber vacuum hose from an auto parts store.
Let me know exactly what the symptoms are on yours and I'll see if I can use that to find a fix for both of us.
I'm having exactly the same problem with my 2000 4X4. Mine is intermittent. I've noticed that it almost always happens when I'm in the desert (100+ degrees) and is often triggered by putting the truck in 4 wheel drive. After 1-6 hours, it usually corrects itself. I've come to a couple of conclusions so far: 1. The vacuum pressure is lost before the line enters the cab. 2. It is being affected by the vacuum actuated auto-locking front hubs. 3. The 4X4 mechanism is very slow to engage sometimes. 4. The Powerstroke has a seperate vacuum pump, rather than a conventional vacuum system on a gas engine.
I think that either the vacuum pump has a problem, or there is a leak somewhere in the vacuum system. I'll try to pin it down and post my fix (if I find one). I've fixed this defroster-only problem on my Mustang and F-150. It was a very simple fix on both. Usually the vacuum lines dry-rot or become brittle and break after five years or so. The break can usually be fixed with some cheap, rubber vacuum hose from an auto parts store.
Let me know exactly what the symptoms are on yours and I'll see if I can use that to find a fix for both of us.
New User
Joined: Jun 2003
Posts: 8
Likes: 0
From: Port Angeles, Wash
everything comes through defroster
I just fixed the same problem. It was a leak at the fitting leaving the oval shaped vacume canister in the tube headed for the AC system. Had to take the whole daggone dash apart to realize there was no vacume underdash.
As for the 4WD, that leak is often right at the wheel where the tube is clamped. With the engine off and key on,(pump running) you can hear it leak when the wheel is turned left and right.
As for the 4WD, that leak is often right at the wheel where the tube is clamped. With the engine off and key on,(pump running) you can hear it leak when the wheel is turned left and right.
New User
Joined: Jun 2003
Posts: 8
Likes: 0
From: Port Angeles, Wash
everything comes through defroster
it sits on the passenger side fenderwell. It`s about a foot long and 6 inches wide or so. (mine is a 1999) The pump sits between the canister and the fender. Hope that helps.
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Freshman User
Joined: Dec 2002
Posts: 46
Likes: 0
From: Midland MI USA
everything comes through defroster
Depending on the year of your truck, there is vacuum under the dash. It's fairly easy to get to on my '99 F350; simply remove the glove box and it's right in front of you. There's a switch unit with several colored vacuum hoses going into it. The hoses look alot like wires but are shinier. There are also two vacuum operated blend door actuators there. If you don't find a leak in the system under the hood, check behind the glove box. One line may have shaken loose there. Or it could be a rare servo failure.
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