How come

jmaxj · Apr 19, 2004

Every time i hit the gas my heater goes to defrost? i thought it was an vaccum issue but there are no breaks or anything that i found in all the lines help it's annoying when it's cold out.

derek

5-90 · Apr 19, 2004

Vacuum reservoir. On Renix XJ's, it's in the bumper, I think it's front and centre on later models. It's either a ball shape or a cylinder with rounded ends.

It won't register as a "leak" when it fails, but there is a check valve in it that holds vacuum (when it works.) When the check fails, it won't hold vacuum and you will get the symptoms you describe with no leak to be found. Replace it.

Since the plenum dampers are held with constant vacuum, a loss of the vacuum cannister will cause the shift you describe. I have the same issue in my 88 and my 89, but I just do a quick idle to return th "heat" when my face gets too warm... I guess I should fix those one of these days...

5-90

RichP · Apr 19, 2004

Check the vac hose that runs under the battery, battery splooge generally eats it away and you get a leak.

Matthew Currie · Apr 20, 2004

5-90 said:
Vacuum reservoir. On Renix XJ's, it's in the bumper, I think it's front and centre on later models. It's either a ball shape or a cylinder with rounded ends.

It won't register as a "leak" when it fails, but there is a check valve in it that holds vacuum (when it works.) When the check fails, it won't hold vacuum and you will get the symptoms you describe with no leak to be found. Replace it.

Since the plenum dampers are held with constant vacuum, a loss of the vacuum cannister will cause the shift you describe. I have the same issue in my 88 and my 89, but I just do a quick idle to return th "heat" when my face gets too warm... I guess I should fix those one of these days...

5-90

It's still front right on the 95. I don't know if they changed it for 97, though.

jmaxj · Apr 22, 2004

RichP said:
Check the vac hose that runs under the battery, battery splooge generally eats it away and you get a leak.

My canister is now under the hood cause i built a tube bumper and it was in the way so that couldn't be it that line no longer is there, as for when i moved it i had a line undone and didn't know it and my vacuum disco wasn't working so i fixed that, don't those run off the same canister? or should i just replace the canister to see?

oldmopars · Apr 22, 2004

If its like my 89, the canister has 2 sides, one could be good and the other bad.

jmaxj · Apr 23, 2004

oldmopars said:
If its like my 89, the canister has 2 sides, one could be good and the other bad.

two sides like a line going in on each end? or just split in middle?

oldmopars · Apr 23, 2004

Mine has 4 lines going in/out of it. 2 in each end. The canister that is in my 89 has a seam in the middle, like 2 small cans merged into one long can.

jmaxj · Apr 24, 2004

oldmopars said:
Mine has 4 lines going in/out of it. 2 in each end. The canister that is in my 89 has a seam in the middle, like 2 small cans merged into one long can.

mine has the seem in the middle but only one line goin in, there is a t about 6 inches away that goes into four lines.

How come

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