Hot water shut-off valve

[Fishman]

I read this on another members site and saved it a while back... I actually forgot who's site it was. This does sound 100% like my current situation. When my AC is on, I can hang meat in the car... when it's not, I get hot air blowing... no matter the setting.

"Install a hot water shut-off valve. C-3's constantly circulate hot water through the heater core. It is nearly impossible to get cool, unheated air moving through the vents, without running the A/C. Install the shutoff, using common plumbing supplies, and cool off. When cold weather returns, a quick trip under the hood will bring warm air back. I actually waited two miserable years before doing this."


Any one try this? Better yet, any pics?

Signed,
Miserable (Fishman)

 

[Bob Chadwick]

I actually installed one in each of the two lines. I've got a pictures of the single valve installed at my web site.

 

[photovette]

You do not need those manual cutout valves; the vacuum operated valves work just fine. How the rumor got started that a cheap garden hose valve worked better than the standard valve is beyond me. If coolant is leaking by it, the vacuum operated valve is faulty and needs to be replaced--not eliminated!

You need that heat valve for mild days--unless you like hearing your wife complain about how cold it is in the car.

 

[vmrod]

C'mon, you should know better. Most wives would just find something else to complain about!

 

[soppeng]

There is a step by step process with a good description and photographs at the corvettefaq.com website under the subject heading "cooling": This shortcut should get you there: http://temp.corvetteforum.net/c3/joeveto/Hot_Water_Shut-Off.shtml

 

[tomtom72]

Hi all, I don't know if this is correct, but I remember that my 72 LT-1 A/C coupe did not have a heater control valve like all other GM cars. I didn't see anything in the GM shop manuals that I had gotten from the original owner(he ordered the manuals when he ordered the car) about a heater control valve. The heater controls only controlled the diverter doors, so I would think that hot water was always in the heater core. I know two things for sure. My friend's 69 SS396/350 camaro had A/C and a heater control valve and the temperature of the air on the vent setting was much cooler than in my vette. Ofcourse there was so much radiated heat coming from the fire wall and trans tunnel that you almost didn't notice what was coming out of the vent sys! You would never freeze to death in my 72! I always wondered why GM never put a heater control valve in the car? I remember reading somewhere, owner's manual I think, that there was a tip if you were caught in B to B traffic: use manual over rides to open headlight doors, wiper door, and if it gets really bad pop the hood release, and then as a last resort turn on the heater. I remember using those tips on a hot summer's day many a time!

 

[72Mako]

Installed a shutoff valve on my '72 some years back. Works great, got tired of the constant heat blowing out of the vents during the summer. Charles

 

[80convertible]

I've had a manual valve for about 4 years. Cabin is much cooler in the summer. I purchased heavy duty brass valve from Ace Hardware.

 

[Fishman]

One... or two?

Thanks for the replies...

Has anyone else,either than bobchad, installed two manual valves (one on the supply and one on the return line)?

Later all... Brian

 

[photovette]

The biggest heat gain is the lack of insulation on the evaporator box--look how close it is to the exhaust manifold. What I did is to cover it with insulation pads from a Volkswagon's a/c box.

 

[80convertible]

Thanks for the replies...

Has anyone else,either than bobchad, installed two manual valves (one on the supply and one on the return line)?

Later all... Brian

Nothing wrong with adding two valves, but I'm not sure why you would. If you shut off flow to the supply line, there is not coolant flowing thru the return line. At least that's what I thought:confused

 

[Fishman]

What I did is to cover it with insulation pads from a Volkswagon's a/c box.

Hey photovette...

I know you got a camera ... can you take a nice picture? (of the insulation I mean).

 

[Bob Chadwick]

Nothing wrong with adding two valves, but I'm not sure why you would. If you shut off flow to the supply line, there is not coolant flowing thru the return line. At least that's what I thought:confused

I thought the same thing but the heat must transfer through the water even without the flow. Adding the second valve seemed to be good for a couple of degrees.

 

[Fishman]

Thanks Bob...

I really enjoy your site... very informative. Thanks.

I (for some reason) still have doubts about needing both valves; unless the engine somehow pumps coolant back through the return hose when the supply line is off?

I am going to install the one, and then see what happens. It's a pretty cheap trial... I have plenty 'o hose around.

Later... Brian