j.kenzie@sbcglobal.net

Robert,
Nice graphics and nice idea.

bd0nalds0n

Okay, next question--what does the relay look like?

IcemanG17

Hmm
I can find one small problem.....what happens when the vacuum tank runs out? Sure our cars instantly open the heater valve when they are shut off....but I would guess this mod will only stay closed for a couple hours (less on cars with vac leaks)....??

heinrich

nice work. excellent drawings.

heinrich

Brian no vac == no heat == closed.

rcoble

with this mod the 'no-vacuum' state is the 'no-hot-water' state.

SharkSkin

Nice mod... I don't think I have a solenoid to control the heater valve though. I have another solution in mind....

Earl Gillstrom

Gary Knox developed a heater valve fix a long time ago that may be a lot easier to implement. It is on my website. I just looked at it and both of our Email addresses have changed, so don't use the ones on the writeup.
http://members.rennlist.com/captearl...rvalvemod.html

rcoble

You should have your heater valve controlled by the one of the vaccum valves behind the center console. Looks like this:


One of these 'vacuum valves' works your 'heater valve'. The 'vacuum valve' is powered by a single wire from your climate controll, Power to wire = vacuum to 'heater valve'. I used a relay to reverse the power to this 'vacuum valve'.

heinrich

Earl, this newb approach does what yours doeasn't do. Yours needs a manual change winter/summer. This thing leaves the heater valve alone, potentially causing it to last far longer, till heat is needed, at which time vac is applied and heat is circulated. I like it No intervention after instal either.

bd0nalds0n

I get that; I guess my question is what kind of relay. I assume it's a relay that's normally closed, but when it gets power, it opens. That's not like a normal headlight/driving light relay, right? Do you have a radio shack part #?

rcoble

Any basic relay will do. there is usualy a diagram printed right on them.
This is the way to hook a relay up to reverse the heater signal.

This is using the normally closed contact.

Alan

Just get an SPDT Bosch type relay - Single Pole Double Throw. Today most generic relays are of this type because they have very little additional expense in manufacturing over a basic SPST relay.

One common (pole) contact usually labeled '30' and 2 switch (throw) contacts - one normally closed - labeled 87a and one normally open labeled "87".

The coils inputs are labelled 85 & 86 - and the 'normally' in this case refers to when the coil is not energized.

So this configuration can easily be made to reverse the polarity of an input signal as shown above.

Alan

bd0nalds0n

Got it. TYVM.

SharkSkin

I don't think my '78 has it. I've had the side panels off the console and spent some time poking around in there, but I wasn't looking for the rack of solenoids at the time so I'm not positive. Brian(Iceman) says all sharks have it, but I think the pre-climate control cars don't. No real use for it anyway, the way the HVAC head works, and besides it's not in the wiring diagram.

This does seem like a very elegant solution for the 80+ cars though!