Vacuum source for dash heater core valve 2003 Itasca Horizon 34HD
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Members are helping diagnose a vacuum line issue on a 2003 Itasca Horizon 34HD, where the dash heater core valve’s vacuum line was likely damaged by rodents. The original poster is unsure where the vacuum source is located. Several experienced RVers suggest that, for diesel models like this, the vacuum is typically supplied by a small electric vacuum pump under the front hood, not directly from the engine. This pump is often near the dash air components and is similar to those used in diesel...
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FIRE UP
Senior Member
RV LIFE Pro
Well Bart,
I don't know if this will help but, here's a pic of the heater control valve in our '04 Horizon 36GD with the CAT C-7 330HP. Being it's an '04 instead of an '03, there may be some differences. But that vacuum hose goes from the valve right into the fire wall and from there, it's into never-never land for me. Sorry, but that's about all I can provide here.
Scott
I don't know if this will help but, here's a pic of the heater control valve in our '04 Horizon 36GD with the CAT C-7 330HP. Being it's an '04 instead of an '03, there may be some differences. But that vacuum hose goes from the valve right into the fire wall and from there, it's into never-never land for me. Sorry, but that's about all I can provide here.
Scott
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Morich
Senior Member
There are two big problems with us getting the good info on the dash heater. One is we get less than the best info on pre 2010 models. We get drawings of parts but not too good about connecting those parts together!
But much of the info is also considered chassis and left to the chassis builders for info.
But there is "some" info on the Winnebago parts listings here:
Skipping down to about page 172, you may find a drawing of the dash heater and some of the parts. Pretty much "exploded drawings" but some idea of what the parts may look like?
Mt thinking without much to back it up, is this:
Item 7 is vac canister, so like where the vac from engine is stored.
That vacuum is then connected to the controls( item 2)for the heat. Whether it comes in on item 3 or a different line, it would then seem to come out of the controls (3) before going to the items 1 and 10 which then do the actual movement of flaps to change what we get when we change the controls.
since the picture Fireup shows a green line, I might first start under the hood looking for a stub of green line that should have been connected to the controls inside. Not to trust the color too much but looking for some stub or loose tubing?
Weird little rodents have to chew to keep their teeth filed down to keep them from growing so long it kills them. So I always try to keep a few rat bars on and around the wires and controls and hope they find them more their flavor than the insulation and such!
But much of the info is also considered chassis and left to the chassis builders for info.
But there is "some" info on the Winnebago parts listings here:
Skipping down to about page 172, you may find a drawing of the dash heater and some of the parts. Pretty much "exploded drawings" but some idea of what the parts may look like?
Mt thinking without much to back it up, is this:
Item 7 is vac canister, so like where the vac from engine is stored.
That vacuum is then connected to the controls( item 2)for the heat. Whether it comes in on item 3 or a different line, it would then seem to come out of the controls (3) before going to the items 1 and 10 which then do the actual movement of flaps to change what we get when we change the controls.
since the picture Fireup shows a green line, I might first start under the hood looking for a stub of green line that should have been connected to the controls inside. Not to trust the color too much but looking for some stub or loose tubing?
Weird little rodents have to chew to keep their teeth filed down to keep them from growing so long it kills them. So I always try to keep a few rat bars on and around the wires and controls and hope they find them more their flavor than the insulation and such!
markhbike
Senior Member
Bart, some background info, since you have a diesel engine the vacuum comes from a small vacuum pump likely under the front hood near you dash air, not the engine. These can be found in most auto parts stores as they are the same as what most diesel pickups use for dash vacuum supply. I have a 2007 Journey 36G with an CAT 350 HP and have had to change mine out twice. Near the pump should be a small tank, mine is round and about the size of a softball. You can hear the pump run when you turn on the key to start the engine. It is in the generator front hood compartment on the drivers side. However, this doesn’t help you find the other end of your cut/chewed line. You will have to look around the other end should be near by. You can buy replacement line and fittings at most auto parts stores. These lines are controlled by valves on the dash from the dash heat/AC controls. You should be able to get to them by removing the dash cover. Good luck.
Morich
Senior Member
I was going with the idea that the part that moves the flap would be the last step in the chain and the actual vacuum source as the far end. In between is the controls at the dash. My thought was that they are likely to need the part from the servo that is missing/chewed off.
I would assume that would be the item 3, listed as vac harness, as it is the part that plugs to the servo.
Seems kind of odd that mice would totally chew the fitting off as they show and it might look more like the line is just loose and hanging but then surprises are common!
But we never know until we get there and we often never hear back what the OP finds.
I would assume that would be the item 3, listed as vac harness, as it is the part that plugs to the servo.
Seems kind of odd that mice would totally chew the fitting off as they show and it might look more like the line is just loose and hanging but then surprises are common!
But we never know until we get there and we often never hear back what the OP finds.
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