Home » Public Forums » GMCnet » Jeep TJ A/C Control Head
| Jeep TJ A/C Control Head [message #366165] |
Sun, 15 August 2021 19:36  |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
Karma: 0
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Today I finished the rough installation of the all the wiring and vacuum lines from the new Jeep control head to the GMC. I had labeled all wires in the dash and on the control, and cut the GM plugs off the wiring going to the stock HVAC panel and used male/female connectors to hook up the Jeep panel.
The Jeep head uses vacuum lines that are the same size in diameter as the GMC. Not knowing how else to connect them, I drilled .250 aluminum rod with a .136 number drill and made female to female adapters. I carefully coated the vacuum lines with RTV, avoiding the ends to prevent clogs, and slid the GMC lines into one end and the Jeep lines into the other. The lines fit snugly into the adapters, but I wanted to minimize leaks, so I glued them in. The Jeep control came with a vacuum pigtail, and I got the chassis end of the pigtail from a wrecked TJ. This way the vacuum lines can still be separated at the pigtail plug.
Once done, I fired up the engine for a vacuum source and began testing the vacuum operation. Everything seems to work pretty good. A turn of the knob, and different modes were selected and the various air doors operated as they should.
I used a blend door actuator from the Jeep on the old cable push pull temp door. It works great. You can turn the temp knob from blue to red and watch the temp door cycle up and down.
I uploaded some pictures on the photo site, here: http://www.gmcmhphotos.com/photos/g7367-interior.html
I tried uploading a video of everything working, but was unable to do so. That's unfortunate, because you can really see the air doors moving in response to the mode knob.
Also, the blower fan DOES NOT run on low all the time now, if the Jeep control ( guess it's now a GMC control, or just A/C control) is turned OFF. This shuts off the blower fan completely. Also, the Jeep control head has built in lighting which I connected to the coach. It will dim with the rest of the instrument lighting.
I need to tweak the defrost door actuator a little bit, but overall, I am very happy with the outcome.
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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| Re: Jeep TJ A/C Control Head [message #366168 is a reply to message #366165] |
Sun, 15 August 2021 20:28  |
Bill Van Vlack
Messages: 419
Registered: September 2015
Location: Guemes Island, Washington
Karma: 14
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Great job!
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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| Re: Jeep TJ A/C Control Head [message #366242 is a reply to message #366165] |
Fri, 20 August 2021 15:51 |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
Karma: 0
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I just wanted to report that the new Jeep control head works perfectly with the GMC a/c system. I now have Fan OFF, LOW, MED, and HIGH speeds. The Temperature control moves the blend door from fully open (cold) to fully closed (hot), and anywhere in between. The mode switch energizes the compressor at RECIRC, A/C, DEFROST/HEAT and DEFROST. The defrost door, formerly held shut by a spring, is now held shut by vacuum except for DEFROST/HEAT and DEFROST. In the event of loss of vacuum, the system now defaults to DEFROST instead of DASH AIR. The dash air flap, heat flap, and recirculating flaps all move into position as they should, with NO VACUUM LEAKS! In DEFROST/HEAT mode, the heat door and the defrost door both open to about half way.
To make this work, I removed the spring from the defrost door, and modified the defrost vacuum actuator to be normally open, and close when vacuum is applied. I have since been told that there are vacuum solenoids available that can use a lack of vacuum signal to apply vacuum to another port. This would have enabled me to do the same thing without modifying the vacuum actuator bracket, so that's an option for someone else if they go this route.
I also removed the spring from the dash air door, which held it open at all times until vacuum was applied. I reversed the action of the dash air actuator as well so that is now closed by the vacuum signal from the Jeep head. The Jeep head applies vacuum to almost every line in every position, EXCEPT in defrost. That is so that the Jeep defaults to defrost in the event of vacuum loss. Safety reasons I assume. My coach was dash air flap open in the default situation, and I never had anything in the vacuum system to work until now.
Anyway, I was tickled to death with the final results, so I had to share. So now I am finishing up wiring the new gauges and ready to start on my fiberglass A/C ducts. The defrost ducts are done except for cutting 6 holes in them to receive the moveable registers, so that has to be done as well.
I am moving some more pictures to the photo site.
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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| [GMCnet] Re: Jeep TJ A/C Control Head [message #366243 is a reply to message #366242] |
Fri, 20 August 2021 16:11 |
Randy Hecht
Messages: 93
Registered: March 2019
Location: Roswell, GA
Karma: -5
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Have all this in pictures and parts list by chance? Like to modify my 1974.
Randy Hecht
Roswell, GA
1974 Canyon Lands GMC Motor-coach
> On Aug 20, 2021, at 16:52, Greg Crawford wrote:
>
> I just wanted to report that the new Jeep control head works perfectly with the GMC a/c system. I now have Fan OFF, LOW, MED, and HIGH speeds. The
> Temperature control moves the blend door from fully open (cold) to fully closed (hot), and anywhere in between. The mode switch energizes the
> compressor at RECIRC, A/C, DEFROST/HEAT and DEFROST. The defrost door, formerly held shut by a spring, is now held shut by vacuum except for
> DEFROST/HEAT and DEFROST. In the event of loss of vacuum, the system now defaults to DEFROST instead of DASH AIR. The dash air flap, heat flap, and
> recirculating flaps all move into position as they should, with NO VACUUM LEAKS! In DEFROST/HEAT mode, the heat door and the defrost door both open to
> about half way.
>
> To make this work, I removed the spring from the defrost door, and modified the defrost vacuum actuator to be normally open, and close when vacuum is
> applied. I have since been told that there are vacuum solenoids available that can use a lack of vacuum signal to apply vacuum to another port. This
> would have enabled me to do the same thing without modifying the vacuum actuator bracket, so that's an option for someone else if they go this route.
>
> I also removed the spring from the dash air door, which held it open at all times until vacuum was applied. I reversed the action of the dash air
> actuator as well so that is now closed by the vacuum signal from the Jeep head. The Jeep head applies vacuum to almost every line in every position,
> EXCEPT in defrost. That is so that the Jeep defaults to defrost in the event of vacuum loss. Safety reasons I assume. My coach was dash air flap open
> in the default situation, and I never had anything in the vacuum system to work until now.
>
> Anyway, I was tickled to death with the final results, so I had to share. So now I am finishing up wiring the new gauges and ready to start on my
> fiberglass A/C ducts. The defrost ducts are done except for cutting 6 holes in them to receive the moveable registers, so that has to be done as
> well.
>
> I am moving some more pictures to the photo site.
> --
> Greg Crawford
> KM4ZCR
> Knoxville, TN
>
> "Ruby Sue"
> 1977 Royale
> Rear Bath
> 403 Engine
> American Eagle Wheels
> Early Version Alex Sirum Quad bags
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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| Re: Jeep TJ A/C Control Head [message #366246 is a reply to message #366165] |
Fri, 20 August 2021 18:11 |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
Karma: 0
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Senior Member |
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I have pictures on the photo site. Parts list is pretty basic. New or used 98-2005 Jeep TJ control head, wiring harnesses, and blend door actuator. The rest of the parts are made on my lathe or mill.I built a new dash, you would need to enlarge the hole on the stock dash.
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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| [GMCnet] Re: Jeep TJ A/C Control Head [message #366248 is a reply to message #366246] |
Fri, 20 August 2021 18:58 |
Randy Hecht
Messages: 93
Registered: March 2019
Location: Roswell, GA
Karma: -5
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Member |
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Thanks, that works
Randy Hecht
Roswell, GA
1974 Canyon Lands GMC Motor-coach
> On Aug 20, 2021, at 19:11, Greg Crawford wrote:
>
> I have pictures on the photo site. Parts list is pretty basic. New or used 98-2005 Jeep TJ control head, wiring harnesses, and blend door actuator.
> The rest of the parts are made on my lathe or mill.I built a new dash, you would need to enlarge the hole on the stock dash.
> --
> Greg Crawford
> KM4ZCR
> Knoxville, TN
>
> "Ruby Sue"
> 1977 Royale
> Rear Bath
> 403 Engine
> American Eagle Wheels
> Early Version Alex Sirum Quad bags
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
_______________________________________________
GMCnet mailing list
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| [GMCnet] Re: Jeep TJ A/C Control Head [message #366249 is a reply to message #366246] |
Fri, 20 August 2021 19:45 |
sgltrac
Messages: 2797
Registered: April 2011
Karma: 1
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Senior Member |
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You should build a kit with instructions and parts list. The factory
controls are worn out and clunky if not. Sell it.
Sully
Bellevue wa
On Fri, Aug 20, 2021 at 4:11 PM Greg Crawford
wrote:
> I have pictures on the photo site. Parts list is pretty basic. New or used
> 98-2005 Jeep TJ control head, wiring harnesses, and blend door actuator.
> The rest of the parts are made on my lathe or mill.I built a new dash, you
> would need to enlarge the hole on the stock dash.
> --
> Greg Crawford
> KM4ZCR
> Knoxville, TN
>
> "Ruby Sue"
> 1977 Royale
> Rear Bath
> 403 Engine
> American Eagle Wheels
> Early Version Alex Sirum Quad bags
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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| Re: Jeep TJ A/C Control Head [message #366267 is a reply to message #366165] |
Sat, 21 August 2021 12:41 |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
Karma: 0
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Senior Member |
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I would not be averse to writing up a how-to, if there is sufficient interest. I also still have my factory dash, so I could see if it could be modified easily to fit the Jeep control head.
Some Chrysler products of similar years may be smaller, or not as wide. They would be even better for this, but I have not researched enough to know. I was familiar with the Jeep TJ head, and used it.
If you get into later years, the control heads on most vehicles are incorporated into the on board computer design, and can't be used standalone.
The parts I had to fabricate were the defrost actuator bracket and bell crank, the blend door actuator adapter that fits over the factory hot/cold door lever, the bracket that holds the blend door actuator, and
the dash air flap pivot hinge pin and attaching brackets.
It's not technically difficult, just time consuming.
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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| Re: Jeep TJ A/C Control Head [message #366395 is a reply to message #366165] |
Mon, 30 August 2021 19:41 |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
Karma: 0
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Senior Member |
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So I was out at the coach today, measuring my foam and trimming it for laying up the passenger side ductwork. Driver side ductwork fiberglass is now complete.
I looked down at the air box, and noticed that the dash air flap was open. Since the system now defaults to defrost, I was a little concerned that something was wrong. Then I looked at the mode switch.
It was in A/C mode. Yep, three days after the engine was ran last for testing, the system IS STILL HOLDING VACUUM! I switched it to OFF, and the dash air flap slowly closed.
I am overjoyed!
I can tell from lack of responses to this thread that there is not a lot of interest in this project, but I was so excited I had to share. Feel free not to read! Oh, and by looking at the factory dash parts, I
believe that anyone could replace the factory A/C head with the Jeep head with just a little cutting/filing on the steel backing plate and plastic dash bezel. It's slightly larger than stock.
If a vacuum solenoid that actuates with a lack of vacuum signal to a sensing port is available, this would eliminate the hardest part of my modifications. Someone had mentioned that this is possible.
If that is the case, then total disassembly of the dash would not be necessary to do this mod.
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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| Re: Jeep TJ A/C Control Head [message #366396 is a reply to message #366395] |
Mon, 30 August 2021 19:58 |
Bill Van Vlack
Messages: 419
Registered: September 2015
Location: Guemes Island, Washington
Karma: 14
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Senior Member |
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Greg C. wrote on Mon, 30 August 2021 19:41
I can tell from lack of responses to this thread that there is not a lot of interest in this project, but I was so excited I had to share. Feel free not to read!
Au contraire!... This is a great upgrade and a true solution for the disappearing vacuum disks in the OEM controls. I think a kit or a step-by-step photo essay would be a big hit! If there was a way to preclude modifying the OEM opening that would be even better. I have a '76 that uses the recirc damper actuator reconfigured as the 'max air' damper - it bypasses the heating coil and directs all the air through the cooling coil - so that may affect how the system is arranged.
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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| [GMCnet] Re: Jeep TJ A/C Control Head [message #366399 is a reply to message #366395] |
Mon, 30 August 2021 21:45 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
Karma: 0
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Senior Member |
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Don’t underestimate the interest or the utility in this mod. It’s really cool and has potential
Sent from Mail for Windows
From: Greg Crawford
Sent: Monday, August 30, 2021 7:41 PM
To: gmclist@list.gmcnet.org
Subject: [GMCnet] Re: Jeep TJ A/C Control Head
So I was out at the coach today, measuring my foam and trimming it for laying up the passenger side ductwork. Driver side ductwork fiberglass is now
complete.
I looked down at the air box, and noticed that the dash air flap was open. Since the system now defaults to defrost, I was a little concerned that
something was wrong. Then I looked at the mode switch.
It was in A/C mode. Yep, three days after the engine was ran last for testing, the system IS STILL HOLDING VACUUM! I switched it to OFF, and the dash
air flap slowly closed.
I am overjoyed!
I can tell from lack of responses to this thread that there is not a lot of interest in this project, but I was so excited I had to share. Feel free
not to read! Oh, and by looking at the factory dash parts, I
believe that anyone could replace the factory A/C head with the Jeep head with just a little cutting/filing on the steel backing plate and plastic
dash bezel. It's slightly larger than stock.
If a vacuum solenoid that actuates with a lack of vacuum signal to a sensing port is available, this would eliminate the hardest part of my
modifications. Someone had mentioned that this is possible.
If that is the case, then total disassembly of the dash would not be necessary to do this mod.
--
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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Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: Jeep TJ A/C Control Head [message #366409 is a reply to message #366165] |
Tue, 31 August 2021 13:24 |
Tilerpep
Messages: 404
Registered: June 2013
Location: Raleigh, NC
Karma: 7
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Senior Member |
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Greg,
Please don't use active responses here to determine value of your post! Between current interest that the reader may need a free day to tinker and figure out current status (like me) and future interest of the searchable forum...posting stuff you find can work is great! As they age, we need more options, and twenty people might need it next year!? Who knows...
Inspired by your first post, I went out and stuck an inspection cam up every port and access on my 1975 to see what of mine is working and what is not. There is a strange combination of which vents and intakes, but now I have it recorded.
I know for a fact my 78 hvac control needs a new head, or at least the hard to come by wheel thing. PO left the dash cover off for years in nearly full sun. that little control wheel for the vacuum just crumbled. May end up with your Jeep solution. So count me in as one who might use every scrap of info you post about! Thanks
1975 Glenbrook, 1978 Royale rear bath
Raleigh, NC
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| [GMCnet] Re: Jeep TJ A/C Control Head [message #366414 is a reply to message #366409] |
Tue, 31 August 2021 15:15 |
sgltrac
Messages: 2797
Registered: April 2011
Karma: 1
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Senior Member |
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I second (third?) Tyler’s response. The mechanical AC/HEATER controller was
my biggest head scratcher when contemplating my custom dash several years
ago. This Jeep controller will become more and more relevant as time
passes. Since you have already done the fieldwork and trial and error you
might want to take the time to document the journey.
Sully
Bellevue wa
On Tue, Aug 31, 2021 at 11:25 AM Tyler wrote:
> Greg,
> Please don't use active responses here to determine value of your post!
> Between current interest that the reader may need a free day to tinker and
> figure out current status (like me) and future interest of the searchable
> forum...posting stuff you find can work is great! As they age, we need more
> options, and twenty people might need it next year!? Who knows...
>
> Inspired by your first post, I went out and stuck an inspection cam up
> every port and access on my 1975 to see what of mine is working and what is
> not. There is a strange combination of which vents and intakes, but now I
> have it recorded.
>
> I know for a fact my 78 hvac control needs a new head, or at least the
> hard to come by wheel thing. PO left the dash cover off for years in nearly
> full sun. that little control wheel for the vacuum just crumbled. May end
> up with your Jeep solution. So count me in as one who might use every scrap
> of info you post about! Thanks
>
> --
> 1975 Glenbrook, 1978 Royale rear bath
> Raleigh, NC
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
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Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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| Re: Jeep TJ A/C Control Head [message #366452 is a reply to message #366165] |
Thu, 02 September 2021 11:22 |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
Karma: 0
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Senior Member |
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Thanks, all, for the responses. I do plan on documenting everything better on the photo site, but it is difficult for me to use. I can only download two pictures at a time, otherwise, you think you have successfully uploaded to the site, only to find out that you have not.
It's probably more user error than anything. I may have to put together a slideshow presentation or something.
I wasn't ready to start this project when I did. It just worked out that way because one thing led to another. I'm trying to get it all buttoned up for some camping trips this month, and then I'll know how well everything is working.
I discovered my start battery is bad (2016 vintage) and I've lost the freon charge while working on the timing chain and A/C project, so I have to address those as well.
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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| Re: Jeep TJ A/C Control Head [message #366453 is a reply to message #366165] |
Thu, 02 September 2021 11:46 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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That sounds like the new hot set-up! I would definitely be interested in doing this or something similar in the future, as required, to make my dash air/heat/defrost system continue to work.
It sounds a little complicated, but once I would see it in pictures and instructions, it probably won't be that hard to execute.
Thanks for experimenting with this and sharing your successful results. Very encouraging!
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Jeep TJ A/C Control Head [message #366472 is a reply to message #366453] |
Fri, 03 September 2021 21:51 |
JohnS
Messages: 126
Registered: December 2014
Location: Vacaville, CA
Karma: -2
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Senior Member |
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I am very interested in this too, as my 9 port valve (made of unobtanium) is leaky and unreliable.
This looks like a solution that would be more reliable and extend parts availability.
John Shutzbaugh
John Shutzbaugh, Vacaville, CA, ncserv@aol.com;
78 Buskirk stretch, "What were we thinking?"
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