New dash underway

Same question as Keith... I see on your FB page you used a Jeep actuator for the blend door; Did you use pneumatic (vacuum) relays for the dampers?
--
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid
November 2015.
 
Modern vehicles default to defrost mode in the event of vacuum failure. My coach did not. It defaulted to dash outlets. So the two biggest challenges
in adapting a modern control head were addressing the defrost issue and also the temperature control cable. The Jeep/Chrysler control head was
selected because it is a simple unit that is not connected to the car's ECU like many of the later fancier heads. The temperature is controlled by the
Blend Door Actuator, a simple stepper motor type unit that rotates a shaft connected to the blend door to accomplish the temperature changes. I used
the factory Jeep TJ blend door actuator, again, simple and relatively cheap, available on ebay. I removed the plastic actuator shaft from the unit and
turned an aluminum one on my lathe. A simple turning with a chunk cut out of the recess allows this adaptor to fit over the factory TZE blend door
lever, where the factory cable attaches. I cut out a piece of aluminum plate with some machine screws and spacers, to space the BDA (blend door
actuator) out from the factory airbox and place the aluminum drive adaptor over the blend door lever. When wired to the control head, the BDA now
opens and closes the factory blend door as it should. I was afraid the rotation might be opposite of needed, but it works.

The next challenge was the defrost door. The coach has a spring that holds the defrost door shut, and the vacuum pot opens it in the defrost position
on the factory head. I removed the factory vacuum pot mount. It was held on by 5 heavy duty spot welds. Overkill. I removed the factory spring. Using
the old mount, I welded on a little stand and fabricated a bell crank out of aluminum scraps. The mount was relocated in a slightly different position
to accommodate the bell crank and get the correct angle on the defrost door. Basically, I reversed the action of the factory vacuum pot from opening
to closing.

The Jeep head applies vacuum to the Jeep defrost door at all times EXCEPT for when you call for defrost. Then the Jeep defrost door opens. So on the
coach, the Jeep control head will apply vacuum to the defrost door pot, causing it to close. The opposite of what the coach control head does. So now
my coach defrost acts like the Jeep system, with defrost being the default mode in the event of vacuum failure.

I will be happy to answer any questions anyone has. Since I am still constructing the dash, everything is not yet installed and working, so there may
be more issues to work out that I have not anticipated.
--
Greg Crawford
KM4ZCR
Knoxville, TN

"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags
 
Greg,

Very clearly written, Greg, good job. 👍

I'm glad you're documenting your work. Keep an eye on doing a presentation at one of the bigger rallies - a lot of people will be interested!

Richard
--
'77 Birchaven TZE...777;
'76 Palm Beach under construction;
‘76 Edgemonte waiting its turn
 
> The next challenge was the defrost door. The coach has a spring that holds the defrost door shut, and the vacuum pot opens it in the defrost
> position on the factory head. I removed the factory vacuum pot mount. It was held on by 5 heavy duty spot welds. Overkill. I removed the factory
> spring. Using the old mount, I welded on a little stand and fabricated a bell crank out of aluminum scraps. The mount was relocated in a slightly
> different position to accommodate the bell crank and get the correct angle on the defrost door. Basically, I reversed the action of the factory
> vacuum pot from opening to closing.
>
> The Jeep head applies vacuum to the Jeep defrost door at all times EXCEPT for when you call for defrost. Then the Jeep defrost door opens. So on
> the coach, the Jeep control head will apply vacuum to the defrost door pot, causing it to close. The opposite of what the coach control head does.
> So now my coach defrost acts like the Jeep system, with defrost being the default mode in the event of vacuum failure.

Thanks for the details, Greg. I wonder if a vacuum switch and solenoid might reverse the action. When the Jeep head removes vacuum the vacuum switch
contacts close and energize the vacuum solenoid, opening the OEM defrost door.

When's the kit coming out?

--
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid
November 2015.
 
Thanks Greg, That control unit is so much better than the stock one, smaller too
Adding to my wish list

Bill, do you know of such a beast? a vacuum operated vacuum relay??
________________________________
From: Bill Van Vlack
Sent: Tuesday, August 3, 2021 12:48 PM
To: gmclist
Subject: [GMCnet] Re: New dash underway

> The next challenge was the defrost door. The coach has a spring that holds the defrost door shut, and the vacuum pot opens it in the defrost
> position on the factory head. I removed the factory vacuum pot mount. It was held on by 5 heavy duty spot welds. Overkill. I removed the factory
> spring. Using the old mount, I welded on a little stand and fabricated a bell crank out of aluminum scraps. The mount was relocated in a slightly
> different position to accommodate the bell crank and get the correct angle on the defrost door. Basically, I reversed the action of the factory
> vacuum pot from opening to closing.
>
> The Jeep head applies vacuum to the Jeep defrost door at all times EXCEPT for when you call for defrost. Then the Jeep defrost door opens. So on
> the coach, the Jeep control head will apply vacuum to the defrost door pot, causing it to close. The opposite of what the coach control head does.
> So now my coach defrost acts like the Jeep system, with defrost being the default mode in the event of vacuum failure.

Thanks for the details, Greg. I wonder if a vacuum switch and solenoid might reverse the action. When the Jeep head removes vacuum the vacuum switch
contacts close and energize the vacuum solenoid, opening the OEM defrost door.

When's the kit coming out?

--
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid
November 2015.
_______________________________________________
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Unsubscribe or Change List Options:
 
> Bill, do you know of such a beast? a vacuum operated vacuum relay??

Not in a single device. I was thinking an electric vacuum switch (like Dave Lenzi provides with his brake booster kits) plus a vacuum solenoid would
probably do it.
--
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid
November 2015.
 
I actually bought a couple of vacuum solenoids for this purpose, but the factory system would only pull the door down, opening it. So the Jeep head
would constantly have the defrost door open until you switched to Defrost mode, then it would close! The opposite of what is needed. So in order to
use the Jeep head, I had to reverse the action of the defrost vacuum pot. Since most modern vehicles default to defrost, this is probably true of most
controls that utilize vacuum to actuate the various doors. Something new utilizing electric actuators could probably be made to work, at the cost of
added complexity.
--
Greg Crawford
KM4ZCR
Knoxville, TN

"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags
 
> I actually bought a couple of vacuum solenoids for this purpose, but the factory system would only pull the door down, opening it. So the Jeep
> head would constantly have the defrost door open until you switched to Defrost mode, then it would close! The opposite of what is needed. So in
> order to use the Jeep head, I had to reverse the action of the defrost vacuum pot. Since most modern vehicles default to defrost, this is probably
> true of most controls that utilize vacuum to actuate the various doors. Something new utilizing electric actuators could probably be made to work,
> at the cost of added complexity.

Get a vacuum switch designed for a vacuum pump (switch closes on low vacuum, opens on high). Connect the Jeep vacuum hose to the vacuum switch.
Connect source vacuum to one side of the solenoid and the actuator to the other side. Low vacuum at the Jeep head (Jeep wants defrost) will close the
switch contacts and energize the solenoid, sending source vacuum to the actuator and opening it. High vacuum Jeep head means no defrost. The vacuum
switch opens, the solenoid de-energizes and closes, and vacuum is removed from the actuator, closing it. The logic works, but there needs to be a way
to bleed off the vacuum from the actuator; maybe a bleed orifice.

--
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid
November 2015.
 
Bill, I have no doubt that your solution would work. In my case, I was more comfortable in modifying the actuator mechanism instead of adding more
vacuum and electrical lines. My original plan was to use a solenoid that was actuated by the signal going to the a/c compressor, but I couldn't figure
out how to isolate the a/c only from the defrost on the control head. If mine works as configured, I'll be happy with it.
--
Greg Crawford
KM4ZCR
Knoxville, TN

"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags
 
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