j.kenzie@sbcglobal.net

Hi Robert,
Very nice idea! I'm getting together the valve and some aluminum. One question: how difficult is it to get the vacuum actuator out of the three slots in the original bracket? Any tricks?
Thanks in advance.
BTW, I have the Gary Knox mod on my a/c syatem and the biggest problem I have is that it's TOO COLD. Sounds strange but there is no modulation of vent temp, just full cold. I'm not that unhappy but it's fun to look at other options which might allow more precise control.

NickT

Way back when I had a 73 Firebird and the heater core went on it.. Major job to get it fixed, no suprise there. When I picked it up, the guy told me that even in the summer time to every once in a while crack open the heater to let the heater core flush through and help prevent the similar rot I had on the old core.

Maybe this was their idea as well.. make sure that each time the car starts a quick shot goes through the core.... Dunno.. fact or fiction??

Mrmerlin

This might be a good way for someone to upgrade the heater control

Hilton

Actually, given that plastics guy (CPR?) was asking for suggestions for parts, and the relative simplicity of this, perhaps he could get a kit made cheaply?

Alan

I don't think too many people are really going to do this one - you have to add a relay and thats a pain for most people. Plus this is a hot location and aluminum may be a better choice to avoid long term brittleness.

I plan to add my relay on the CE panel because its easy for me - done it before - spare relay slots available and most importantly I have stock of all the terminals I need to do this quickly.

Alan

Tom in Austin

You'd think Porsche could have added one more ECU to the 928 ... to sense if the temp setting when the car was stopped was above ambient (in other words, you were using the heater) and then leave the valve open, else close it.

After all they have about 45 other ECUs scattered throughout every square inch of the car's interior ... LOL

Alan

This post came back to life due a thread I posted yesterday about this topic - in that thread there was a suggestion to swap the stock water valve to one that is closed without vacuum and opens with vacuum - this may be an easier way to go... I'm going to pursue this one for my implementation.

Here: https://rennlist.com/forums/showthre...eferrerid=6055

Alan

merchauser

bump

I have been reading some of the (many) HVAC heater valve mod threads and hoping some of the original pioneers might
chime in.

most of the threads are near the 10 year old range, and perhaps some folks who performed mods can give some evaluations

there is the basic mod, which is to tie wrap the heater valve

then I read the gary knox method, of which there is a link provided earlier in this thread

I'll call another, the dr. bob method, to install a ford escort heater valve in line with the original,

and finally ( unless there are more?) the suggestion that alan has proposed.

is there a best, or better method, and does the mod make a nice difference?. like many of the
guys that started these threads, I live in a hot climate, and wonder about the benefit of making these changes

heinrich

My opinion, and experience (different from some who also have equally valuable solutions) is that the inexpensive oldsmobile or whatever it was valve is the best value for time, money, and functionality. It works better than the original, is a direct replacement. I nearly froze to death driving a bought 928 across the Siskyous one January because the heater valve had been ziptied closed, and we had no tools to get to the valve on the drive home after purchase. Ziptie is at best a very temporary fix till you get a new valve in there.

Remember that ziptieing the broken valve also allows a vacuum leak which affects everything from ignition advance to HVAC flaps to automatic transmission.

DR

The "basic Mod" is tried and true, simple to implement, and simple to reverse with no modification to anything. What's not to love???

Cheers,

Dave

merchauser

heinrich, not sure I read about this method. can you point me to a thread or elaborate more??

dave, I like the basic as well, but can you comment on downsides, like the post below from heinrich? does ziptieing the valve create any issue(s)??

DR

I only recommend doing it on a good valve. Doing that to a known bad valve makes no sense to me.

Cheers,

Dave

merchauser

mine is only a few months old: so no downside?? do I also cap the plastic vacuum line from the console solenoid, or leave as is?

DR

No downside I can think of, leave vacuum line alone as long as it is optimal.

Happy Monday,

Dave

merchauser

thank you for your input, dave! much appreciated

would still like to hear about the "Oldsmobile?" valve method, as well as those who have gone to greater lengths
and results experienced.