Rear A/C for 1969 T&C Wagon - Dealer Ad on Option and Use of R290 Refrigerant

[Sport Fury 67]

While working on my 1969 wagon with rear a/c, I noted that the dash did not have a panel switch for off/low/high for the rear fans. The positive feed leads for the rear blower motors were connected directly to the rear tabs for the fan control switch above the push button controls. Also, when I pulled the rear seat and obtained the build sheet, there is a code "51" for a Heat - A/C car, but nothing indicating rear air.

Question - Back in the day could a dealer install rear A/C in a wagon if the seller requested it added?

I am deciding on how to resurrect the A/C based on the current state of the System - wagon has over 100K miles. With what I have read about the recent changes for R134A, and acknowledge the compressor most likely will need to be re-build, along with a new dryer and replacing the front evaporator core, would I be better off crimping- sealing the lines to the rear A/C and use R-12 with the "standard' Heat- A/C under dash components, or, use the newer Butane-Propane R290?

My concern about the rear AC is there are feed lines, hoses, fittings, components located behind aged plastic panels that most likely will fall apart and will require replacement with parts that need to be custom made.

It is not anticipated the future use of the wagon will be full of people driving through the desert and I want to keep it simple. Its a nice wagon but not a trailer queen. Just want it to functional and reliable for a couple of years.

Comments or any experiences with R290 refrigerants and rear A/C system would be appreciated.

 

[CBODY67]

Check out the @TxDon thread on upgrading his '66 Monaco wagon to a Sanden and related parts. It was a factory dual a/c car.

Only factory add-on systems were for just the front system, not adding the dual system to an existing factory a/c car.

As for the fan motor, check the factory service manual wiring schematics for verification of what was what, back then. Perhaps @Ross Wooldridge, who had a factory dual a/c car might have some input?

You will still be cooling the huge expanse of area behind the driver's seat in the wagon, much less all of the rear glass area's heat load, too.

A bad thing about the use of (for the time) high-tech plastic for interior panels is that with age, the plastic will shrink and crack (of its own accord), if not just "go thin". The plus side is that many of those cracked panels can be glued back together and recovered with stretchable vinyl . . . possibly. If not carefully glued and re-colored. Might make more work to do that, but not impossible.

I saw a Scotty Kilmer video on R52 being used to replace the much more expensive R1234yf gas in a late-model Honda car. A close cousin that apparently works.

Even from the earlier days of R-134a avoidance, there have been some "hybrid" gasses that included butane, if not pure butane itself. No experience with that, but possibly others have?

CBODY67

 

[3175375]

My experience with ‘rear’ air comes from non-Mopar equipment.
I had a 95 GMC Suburban with rear air and heat. It always took a while for it to become noticeable, due to the longer hoses, I suspect.

Secondly, I currently own and operate a 38’ RV that has an engine driven dash a/c unit that uses R-134a.
It too, takes a while for it to develop cold air (and heat), due to the long hoses.

My advice is to inspect and ensure that you have a near perfect charge if you’re going to use R-134a. I would also recommend using a scroll compressor (Sanden) as they are more efficient and effective.

I am sure others will chime in.

 

[Davea Lux]

R-290 is propane. It is an effective refrigerant but it is also flammable. It would be important to be sure the system is leak free. The factory compressor should survive with R-290. The front evaporator on most Mopars is pretty durable, they usually did not leak unless there was rodent damage from urine corroding the unit. I would evacuate the system and see if it will hold vacuum before bothering with a core replacement. The other issue with R-12 Systems that were converted to R-134a is that if all of the R-12 mineral oil is not removed, R-134a causes the oil to jell up to where it does not circulate and the compressor burns out. You can add R-290 to an R-12 system without oil breakdown.

If you can find R-12, that is still your best option on these older systems.

Dave

 

[Ross Wooldridge]

In my 66 T&C with factory Rear AC, the rear circuit's freon lines are connected directly to the front circuit's freon lines by splitters near the firewall. The blower fan for the Rear AC are independently controlled by a switch on the dash, and can be on or off whether the front HVAC system's fans is on or not.

This means that the freon is always circulating through both systems when the compressor is engaged, regardless as to whether or not the blower fan is on or not for the Rear AC.

If or how that setup changed in subsequent years (and perhaps it did), I don't know.

I am not aware that the dealer could add a Rear AC system to a wagon as an after-purchase option. Using factory parts, it would have been viciously expensive, as it would have involved gutting a large portion of the interior at the rear seat area (headliner, side shields changed out), plus running lines and drilling holes and adding the drain hoses. Not cost effective to ever have offered a retrofit package.

If you can show pictures of your system's installation, and include some pics of the dashboard controls, it would help.

It is very likely a factory assembly line install, and if the Rear AC blower comes on with the front blower, it's an "always on" dual system. However, I would believe it should have been a dash mounted "Rear Air" fan switch, and that perhaps it crapped out and someone connected it to the HVAC switch.

Regarding choices of refrigerant: I had my system properly converted to R134A many many years ago - the system was truly and properly evacuated and flushed of any and all traces of the R12 and its compressor oil, and new R134A stuff installed. The system worked splendidly for years, but required top-ups of refrigerant periodically, which was expensive.

I have switched to DuraCool (which is Butane based), which DuraCool claims repeatedly is backwards compatible to ALL systems oils, and will NOT harm or gum up.

I have had success using it for likely 20 years now, no issues, no worries, top it up every 2 years or so with a can or two from Walmart, and it cools like a meat locker. This picture was taken this summer. That's 18 degrees Farenheit out of the front vents.

 

[Sport Fury 67]

Thank you all for your replies and your comments. The wagon was parked in 1982. When the engine was freshened a few years ago, I was told the A/C System still had some pressure when it was dis-connected. The wagon was kept in a garage in Anaheim, CA and there is no rodent or other critter damage, its rust free - just a lot of dirt-dust from sitting.

Without dis-assembling all the A/C interior plastic covers - cladding, I did not know how the rear air was plumbed - thank you Ross for your comments.

I procured a rear - air fan motor switch and was fortunate that it had the original wiring included. The green colored "hot" wire for the rear fans connected into the "Y" shaped acessory connector under the dash. Previously they were pulling the power from the dark green colored wire for the main fan motor switch.

The blue colored wire from the time delay to the compressor is missing, so I have to fabricate that and determine if the clutch is still operational on the compressor. I did not want to run the compressor on an empty system.

Since the system is "empty" would it be best to replace the o-rings in the various connections, then pull a vacuum and see if it holds? If we are good at that point, we can try to fill the system with DuraCool. I read in the shop manual the A/C required for 3 lbs of R-12 and it requies and extra 1 lbs for rear air applications. I understand the amount of Duracool required to R-12 is 20% less, so one method could be to intially fill to 80 % then gradualy filll while watching the temp at the vents for stabilization.

Question - Should I replace all of the O-rings in the A/C system under the hood with new ones that are not 50 years old before I pull the vac on the System? Would the "green" colored R-1-34 o-rings work with the DuraCool?

Here are a couple of photos for reference. The front condensor has seen better days, but is may still work. The heater core works very well without leaking, so we are 80% confirdant the the A/C portion under the dash is still good as well. The dryer will be replaced with a standard R-12 component.

Again, comments are appreciate. Got to get the A/C ready for the Illinois winters ; )

]

 

[Ross Wooldridge]

You said: "The blue colored wire from the time delay to the compressor is missing, so I have to fabricate that and determine if the clutch is still operational on the compressor. I did not want to run the compressor on an empty system."

It's easy to test the clutch, but if there's no freon or compressor oil in the system, only do it for a very sort time - with the engine running, put 12V directly to the wire going to the compressor - you can see it clipped to the compressor body, so just find its connector and apply 12V there. If the front plate on the clutch starts turning, the compressor clutch works.

You said: "Since the system is "empty" would it be best to replace the o-rings in the various connections, then pull a vacuum and see if it holds?"

Yes - you only need to replace o-rings where connections are opened (for example, the dryer).

You said: "If we are good at that point, we can try to fill the system with DuraCool. I read in the shop manual the A/C required for 3 lbs of R-12 and it requies and extra 1 lbs for rear air applications. I understand the amount of Duracool required to R-12 is 20% less, so one method could be to intially fill to 80 % then gradualy filll while watching the temp at the vents for stabilization."

Yes - essentially - watch pressures on the gauges as you refill the system, and watch vent temps. I find it's usually about 60% or so, but it differs with each car. You should get 40 degrees or so idling in the shop, and it will drop considerably when you drive and air is truly cooling the condensor.

Firstly though, you should really flush the system to get the old oil and crap out, and put in new PAG oil. That's done at the condensor, and at the compressor sump. You can also drop about 4 oz into the dryer, since it acts as an oil sump in addition to the compressor. Rule of thumbs is 2oz per component - in a dual system there are 5 components - Compressor, dryer, evaporator front, evaporator rear, condensor. So, roughly 10 oz of PAG oil need to go into a fully flushed and empty system BEFORE charging.

You said: "Should I replace all of the O-rings in the A/C system under the hood with new ones that are not 50 years old before I pull the vac on the System? Would the "green" colored R-1-34 o-rings work with the DuraCool?"

Not necessary - leave 'em alone unless you're opening the fitting, say when you're adding new PAG oil to a component at its fitting.

 

[Davea Lux]

Thank you all for your replies and your comments. The wagon was parked in 1982. When the engine was freshened a few years ago, I was told the A/C System still had some pressure when it was dis-connected. The wagon was kept in a garage in Anaheim, CA and there is no rodent or other critter damage, its rust free - just a lot of dirt-dust from sitting.

Without dis-assembling all the A/C interior plastic covers - cladding, I did not know how the rear air was plumbed - thank you Ross for your comments.

I procured a rear - air fan motor switch and was fortunate that it had the original wiring included. The green colored "hot" wire for the rear fans connected into the "Y" shaped acessory connector under the dash. Previously they were pulling the power from the dark green colored wire for the main fan motor switch.

The blue colored wire from the time delay to the compressor is missing, so I have to fabricate that and determine if the clutch is still operational on the compressor. I did not want to run the compressor on an empty system.

Since the system is "empty" would it be best to replace the o-rings in the various connections, then pull a vacuum and see if it holds? If we are good at that point, we can try to fill the system with DuraCool. I read in the shop manual the A/C required for 3 lbs of R-12 and it requies and extra 1 lbs for rear air applications. I understand the amount of Duracool required to R-12 is 20% less, so one method could be to intially fill to 80 % then gradualy filll while watching the temp at the vents for stabilization.

Question - Should I replace all of the O-rings in the A/C system under the hood with new ones that are not 50 years old before I pull the vac on the System? Would the "green" colored R-1-34 o-rings work with the DuraCool?

Here are a couple of photos for reference. The front condensor has seen better days, but is may still work. The heater core works very well without leaking, so we are 80% confirdant the the A/C portion under the dash is still good as well. The dryer will be replaced with a standard R-12 component.

Again, comments are appreciate. Got to get the A/C ready for the Illinois winters ; )

]

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This looks to be a stock installation of the rear seat air as these fittings are all factory.

Dave