Heater control valve?
Thread Starter
Racer
Joined: Apr 2006
Posts: 417
Likes: 0
From: Tacoma Washington
Heater control valve?
Is it necessary? What function does it actually perform? I'm braiding my heater hoses and wondering if this thing is really needed. Yes, I use the heater, and would like it to function.
NCM Grand Opening Veteran
Joined: Sep 2005
Posts: 20,979
Likes: 384
From: South of giving a damn
St. Jude Donor '11, '17
I assume you are speaking of the vac controlled one in the engine compartment. It allows hot water to flow into the heat exchanger except when the system is in Max AC. Lots of people just use a manual valve & shut it off in the summer, but blending the hot air with the AC air is how you vary the temp coming out of the vents. In Texas, off in the summer is fine as we need the cold air, but in Tacoma you would probably need the blend. So no, if you don't need Max AC you don't need it.
A few things happen when you go to Max AC, exterior air intake doors close & cabin air is routed to the evap, fan kicks into a higher speed & the hot water is turned off by the control valve. This keeps the heater core from adding any heat to the incoming cold air. The only thing the control valve does is keep hot water from circulating in Max AC & when the AC system is in the Off position.
A few things happen when you go to Max AC, exterior air intake doors close & cabin air is routed to the evap, fan kicks into a higher speed & the hot water is turned off by the control valve. This keeps the heater core from adding any heat to the incoming cold air. The only thing the control valve does is keep hot water from circulating in Max AC & when the AC system is in the Off position.
Last edited by ratflinger; May 8, 2006 at 12:11 AM.
Thread Starter
Racer
Joined: Apr 2006
Posts: 417
Likes: 0
From: Tacoma Washington
well poop. My AC isn't working. Seller says it just needs to be charged. He repaired it to hold a charge, but didn't get it done. After looking at pics of various "clean" engine compartments, I've come to like the empty look of the passenger side without the AC and heater control valve and such...Maybe I'll ditch the AC if I can settle with the heat from summer...
thanks for the info.
thanks for the info.
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by BLUSHRK
Maybe I'll ditch the AC if I can settle with the heat from summer...
I like to keep mine in good working order
Burning Brakes
Joined: Mar 2006
Posts: 750
Likes: 82
From: Bedford IN
I left mine out to come back to when i did my engine swap. I am going to have to do it soon because it is starting to get hot here in NC and my feet burn up. It is extremly bad when you are driving in the rain and can not put the windows down.
If that valve is not in there the hot water will continue to run through your heater core and always be heating the cabin even if the fan is not blowing.
If that valve is not in there the hot water will continue to run through your heater core and always be heating the cabin even if the fan is not blowing.
Burning Brakes
Joined: Feb 2006
Posts: 1,024
Likes: 1
From: AL
My car did not have this valve from the factory but I want to add one (already purchased). Also, already have vacuum line added/installed and ready. Now, the engine is out of the car so is perfect time to add, but if I put in wrong place will surely hit something when engine is added. Does anyone have pics of good-best location? BTW, a BB with header sidepipes will be installed. Thanks. . .
Thread Starter
Racer
Joined: Apr 2006
Posts: 417
Likes: 0
From: Tacoma Washington
I'm pretty sure it came from the factory as being zip-tied to the a/c vertical hose that's right behind the overflow bottle. I can't really find another place to put it unless I cut the hoses and install somewhere else.
Burning Brakes
Joined: Feb 2006
Posts: 1,024
Likes: 1
From: AL
an assembly manual shows it being screwed to the evaporator box like the blower relay. it has a flange with two screw holes similar to the relay. but where on the evaporator box is the $64 question? it has to clear everything, etc., etc.
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Thread Starter
Racer
Joined: Apr 2006
Posts: 417
Likes: 0
From: Tacoma Washington
this thing is pissing me off. 
I'm sick of tugging on it to get it exactly in a good spot, so I went and got new heater hose. I'm gonna cut the new hose to accommodate mounting it somewhere on that evaporator box. Problem is that I gotta make a bracket now. 
At least I get to use some power tools! 
I'm sick of tugging on it to get it exactly in a good spot, so I went and got new heater hose. I'm gonna cut the new hose to accommodate mounting it somewhere on that evaporator box. Problem is that I gotta make a bracket now. At least I get to use some power tools!
NCM Grand Opening Veteran
Joined: Sep 2005
Posts: 20,979
Likes: 384
From: South of giving a damn
St. Jude Donor '11, '17
On my 79 SB it was on a bracket that was mounted on top of the exhaust manifold. You can get some new ones that are pretty small. The heater hose should self support the smaller ones. I regularly see them on ebay, just search ebay motors for 19xx corvette.
