Rear heater has a coolant shut-off valve?

Rear heater has a coolant shut-off valve?

Postby roferg69 [OP] » October 1st 2009, 1:11am

Hi guys,

I'm trying to get my rear heater working, and in my factory service manual the diagram for the rear heater coolant lines lists a shut-off valve - but the diagram only points to a section of line that looks like the rest of the line.

Does anybody know where this shut-off valve might actually be on the van itself? I've taken a quick look underneath when doing other stuff under there, but I didn't see anything that looked like a valve. Any suggestions?

Thanks!
"On any pistonhead's automotive wish list, the Corolla fits just above moped and girl's bike."
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1989 - Cavalier Z24 convertible - 253,000km - 2.8L V6
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Re: Rear heater has a coolant shut-off valve?

Postby ghostrider1061 » October 1st 2009, 6:58am

no real idea, but a few minutes on your back or get your van on a lift at a garage mite prove fruitful. if you takr it to a chevy dealer or some one that KNOWS chevy they can lead you in the rite direction.
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Re: Rear heater has a coolant shut-off valve?

Postby Matrixx » October 1st 2009, 7:21am

Hi roferg69

If you have rear heat, then you do have a shut-off valve for it. It will be located (or should be) with the front shut-off valve located just below the heater motor on the passenger side in the engine compartment.:)
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Re: Rear heater has a coolant shut-off valve?

Postby roferg69 [OP] » October 1st 2009, 7:37am

Matrixx wrote:Hi roferg69

If you have rear heat, then you do have a shut-off valve for it. It will be located (or should be) with the front shut-off valve located just below the heater motor on the passenger side in the engine compartment.:)


I actually replaced that vacuum-operated valve last weekend - so the shut-off should be downstream from that guy, eh? Is it more towards the top-side of the van, or underneath?
"On any pistonhead's automotive wish list, the Corolla fits just above moped and girl's bike."
1992 - Safari XT AWD - 252,000km - Engine Type Z - front A/C only
1989 - Cavalier Z24 convertible - 253,000km - 2.8L V6
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Re: Rear heater has a coolant shut-off valve?

Postby Matrixx » October 3rd 2009, 7:21am

Hi roferg69

Hmm? Their should be 2 heater Control Valves with Auxiliary Heat. Here are the diagrams for both (single and auxiliary (#4)):
Attachments
Heater Control Valve Front Heat.jpg
Heater Control Valve Front Heat
Heater Control Valve Front Heat.jpg (42.22 KiB) Viewed 3592 times
Heater Control Valve With Rear Heat.jpg
Heater Control Valve With Rear Heat
Heater Control Valve With Rear Heat.jpg (41.29 KiB) Viewed 3592 times
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Re: Rear heater has a coolant shut-off valve?

Postby roferg69 [OP] » October 3rd 2009, 9:01am

Thanks Matrixx - that's exactly what I think I'm looking for! I'm headed to the wrecker (Pick a Part) tomorrow - hopefully there'll be a van without its motor so I can get a good look at a dead one. Now at least I'll have an idea of where to look!

Do you think this second control valve is vacuum operated too? Probably, eh?

Matrixx wrote:Hi roferg69

Hmm? Their should be 2 heater Control Valves with Auxiliary Heat. Here are the diagrams for both (single and auxiliary (#4)):
"On any pistonhead's automotive wish list, the Corolla fits just above moped and girl's bike."
1992 - Safari XT AWD - 252,000km - Engine Type Z - front A/C only
1989 - Cavalier Z24 convertible - 253,000km - 2.8L V6
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Re: Rear heater has a coolant shut-off valve?

Postby Matrixx » October 4th 2009, 8:53am

Hi roferg69

Yes, it needs to be vacuum operated, as your heater controls inside the vehicle are vacuum assisted to control it. Hope this helps.:)
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Re: Rear heater has a coolant shut-off valve?

Postby $uperJoe » October 5th 2009, 5:30pm

can the front valve be rebuilt? mine is leaking out the side where the actuator arm is. i would hate to spend 30 bucks on it if there is a 20 cent oring kit
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Re: Rear heater has a coolant shut-off valve?

Postby roferg69 [OP] » October 6th 2009, 2:21am

So an update and a few pictures illustrating what I've discovered - and all that's keeping my rear heater from working at 100% is a simple vacuum leak, so now the mystery is solved. One of the two lines running to the Aux Heat Water Valve leaks somewhere between the firewall and the valve itself, so when I get a chance (and some new vacuum line) I'll run a new line - but until then, I hooked up the one that does work so at least I have partial heat back there.
Attachments
Vent-vacuum-diagram.jpg
Shop manual vacuum diagram
Controls.jpg
Which controls for which valves.
Heater-Water-Bypass-Valve.jpg
The "Heater Water Bypass Valve".
Aux-Heat-Valve-Location.jpg
Approximately where the second valve is hiding.
Aux-Heater-Water-Valve.jpg
The "Auxiliary Heater Water Valve".
Cowl.jpg
This is right on the driver's side of the firewall (engine side), right in front of the battery.
Vac-lines.jpg
Which vacuum lines are for which valves.
"On any pistonhead's automotive wish list, the Corolla fits just above moped and girl's bike."
1992 - Safari XT AWD - 252,000km - Engine Type Z - front A/C only
1989 - Cavalier Z24 convertible - 253,000km - 2.8L V6
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Re: Rear heater has a coolant shut-off valve?

Postby roferg69 [OP] » October 11th 2009, 3:17am

And a final update - I replaced the leaking vacuum line and I've got working rear heat! Turns out that some washer fluid hose is exactly the right side to snug over top of the existing line, so a snip at the firewall and a snip at the valve and boom - I've got rear heat again! :D
"On any pistonhead's automotive wish list, the Corolla fits just above moped and girl's bike."
1992 - Safari XT AWD - 252,000km - Engine Type Z - front A/C only
1989 - Cavalier Z24 convertible - 253,000km - 2.8L V6
Original Poster [OP]
User avatar
roferg69
Fueling (3/8 tank)
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