Factory A/C in 1967-1972 Darts

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1967DartSwinger

1967DartSwinger

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I’m curious,how well does the factory air conditioning in these 67-72 Darts work? In looking for one of these online I see that Chrysler amazingly sold a lot with factory air which is great for those of us living in hot weather climates.
Does anyone here have working factoryAC? If so how well does it work?
 
They probably worked great with R12 but with R132 it is a bit different. My understanding is they will still work fine but take longer to cool the car down, not sure why.

Even the heater in my 67 convertible can make it toasty warm (with the top up) in 0 deg weather. not a lot of area to heat or cool
 
A ton of miss information about R134a out there. You don’t need new hoses, you don’t need a special front seal, you don’t need a new expansion valve. Flush the system including the compressor, add the correct amount of PAG or Ester oil, new orings, remove the EPR valve and run it. The PV curve is very close to R12 until you hit pressures over 200-250 PSI and I would run the charge on the low side to not hit these pressures anyway. In my dry climate I don’t worry too much about freezing up but if the factory did not have a evaporator freeze up switch one should be added. The A Bodies seem to have one. B Bodies maybe not so much.

My 68 Coronet will freeze you out with R134a.

My 72 Duster with R134a (with a retro fitted 73 Dart AC box) works poorly. I have spent a fortune trying to understand why. I recently discovered that the 73 AC box is less than a one year design. It was changed again in 74 and stayed till 75 and the end of these A bodies. I am at the point in my troubleshooting that it was in the box. Plan to install the 74+ box (evaporator) this summer. It is starting to feel like the 73 design sucks. Note it is obvious in the pressures. The low side is just too low all the time. The superheat across the evaporator is WAY WAY to high and nothing changes it. It seems like that evaporator design was just not right and I hope it is fixed in the 74+ box.

66 Valiant I just finished with factory AC system and R134a appears to be working as well as the Coronet but time tell after the first 90+ day.

These are all build from NOS seals and valves.

Jim
 
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My factory air in my 69 Cuda works great. It will freeze you out. I did the non ac to ac conversion myself using a system salvaged from a 71 dart. Rebuilt the heater box with a kit from Detroit Muscle. Used the original factory hoses. I bought a new condenser, drier & expansion valve off the internet. Vacuumed it overnight. Charged with R134.
 
I have dealer installed Chrysler Airtemp that still has R12 and it will freeze you out. Of course it is a recirculating type unit but it works well. Kind of ugly but cool at the same time. They call it "Knee Knocker". The new aftermarket systems are modern technology and work well from what I have heard.

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All the factory A/C units are also knee knockers. I have had plenty of factory A/C units and all worked well.
 
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My 1970 Swinger still has its original AC. Converted to 134a many years ago. Cold as ice.

IMG_1008.JPG
 
You do know that the ac and non-ac firewalls are significantly different, right?

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auto-metal-direct-firewall-panel-70 non-ac.jpg
 
1967DartSwinger said:
I’m curious,how well does the factory air conditioning in these 67-72 Darts work?
Click to expand...

In perfect condition they were fairly good. Most of the basic hardware is just fine, and there are ways of greatly improving this system's performance without giant, expensive major surgery. The major bottleneck in this system's performance is insufficient condensing capacity, so the major improvement to the A/C system itself is a parallel-flow condenser rather than the original serpentine type. A parallel-flow condenser has much more condensing capacity than a same-size serpentine condenser, and also quite a lot less flow restriction, which reduces head pressure between the compressor and the condenser, which reduces the torque required to turn the compressor, which reduces the torque peaks applied to the belt, which reduces noise and vibration from the compressor. Since the performance deficit often griped about when running R134a in a system designed for R12 is almost entirely down to inadequate condensing, this condenser swap also takes that off the TS list. Win-win-win-win.

The rest of the improvement comes from doing a much better job of keeping exterior heat out the car, because otherwise you're fighting a losing battle to keep a solar oven cool. That means having all the glass tinted with an eye towards heat blocking, not so much towards darkening the glass (Llumar Air 80, almost invisible and cuts heat entry a LOT), and it means applying good insulation everywhere you can—floorpans all the way up to the firewall, roof and C-pillars, doors, etc.
 
Jim Kueneman said:
My 72 Duster with R134a (with a retro fitted 73 Dart AC box) works poorly. I have spent a fortune trying to understand why. I recently discovered that the 73 AC box is less than a one year design. It was changed again in 74 and stayed till 75 and the end of these A bodies.
Click to expand...

'73 still used a clutch-cycling switch like the '65-'72 systems, adjusted via the warm-cool slider on the dash, to regulate the evaporator temperature, and did not route defogger air through the evaporator to dehumidify it for much better defogger performance. For '74 the A-body got an EPR valve (evaporator pressure regulator, which is what Chrysler called a suction-throttling valve) installed in the intake port of the compressor, just like the bigger cars had been getting since '62; the clutch-cycling switch was deleted, and defog air was routed through the evaporator.

You're right that an R134a swap does not necessarily require new hoses or a new compressor shaft seal, but the EPR valve's calibration is specific to R12, and can really take a bite out of system performance under high demand when R134a is used instead. The best way to avoid this is to delete the EPR valve and install a thermo-sensing clutch cutout switch. It's like the clutch-cycling switch, but not driver-adjustable—you install it so as to stop the compressor when the evaporator gets cold enough to ice up. This technique also affords you some extra system performance if you live in a dry climate where evaporator frost-up is not such a pressing concern; you can install the switch so as to let the evaporator get a little colder than you'd want to allow in a more humid clime.

An R134a changeover practically it really does want a better (parallel-flow) condenser, though. Swap one in and watch your numbers on the manifold gauge get much better.
 
slantsixdan said:
'73 still used a clutch-cycling switch like the '65-'72 systems, adjusted via the warm-cool slider on the dash, to regulate the evaporator temperature, and did not route defogger air through the evaporator to dehumidify it for much better defogger performance. For '74 the A-body got an EPR valve (evaporator pressure regulator, which is what Chrysler called a suction-throttling valve) installed in the intake port of the compressor, just like the bigger cars had been getting since '62; the clutch-cycling switch was deleted, and defog air was routed through the evaporator.

You're right that an R134a swap does not necessarily require new hoses or a new compressor shaft seal, but the EPR valve's calibration is specific to R12, and can really take a bite out of system performance under high demand when R134a is used instead. The best way to avoid this is to delete the EPR valve and install a thermo-sensing clutch cutout switch. It's like the clutch-cycling switch, but not driver-adjustable—you install it so as to stop the compressor when the evaporator gets cold enough to ice up. This technique also affords you some extra system performance if you live in a dry climate where evaporator frost-up is not such a pressing concern; you can install the switch so as to let the evaporator get a little colder than you'd want to allow in a more humid clime.

An R134a changeover practically it really does want a better (parallel-flow) condenser, though. Swap one in and watch your numbers on the manifold gauge get much better.
Click to expand...

Hi Dan

I too read about parallel coil condensers. I have two in the garage right now. I hacked them in to a couple of my cars in the past. I wanted to see the effect before
I spent a bunch of time coming up with mounting brackets. At least in desert SW air the difference was so minimal I could not see any reason to leave them in and spend the effort and ruin the OEM look of my cars.

Also 73 did not have the cycling switch connected to the temp slider. It as all by itself down by the fresh air door wrapped in insulation. The pressures are so far off that the clutch will slip and burn up if you allow it to cycle so I have mine jumped on the Duster. It has way to low suction pressures and way to high pressure on the other side. Literally everything other than the evaporator has been changed out including trying a parallel flow condenser and new OEM style aftermarket one.
 
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Which condenser would you recommend?

My 1973 B body was converted to R134a by the previous owner.
It does a good job of cooling but the evap box under the dash sweats and drips.
It is NOT leaking.

50 on the low side and 225 on the high.
Blows 48 degrees at the vent on max.

I wonder if a more efficient condenser might help.
 
YY1 said:
Which condenser would you recommend?

My 1973 B body was converted to R134a by the previous owner.
It does a good job of cooling but the evap box under the dash sweats and drips.
It is NOT leaking.

I wonder if a more efficient condenser might help.
Click to expand...

Just part of living in a humid climate. There is suppose to be a drip pan in the box to catch the condensation then a way to get it through the firewall. The '73 A bodies had a small tube that was near the passengers feet that took it out through the firewall, the earlier ones the tube was part of the pan and just went through the firewall when you installed the box. Look for that tube (usually about 3/8") and see if it is plugged or maybe it had the transfer tube that is now missing.

The service manual is hard to see but it looks like the Coronet is like the earlier one and it is a direct shot from the back of the box through the firewall. If that is true then it is likely plugged or the catch pan has a rust hole in it.
 
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YY1 said:
Which condenser would you recommend?

My 1973 B body was converted to R134a by the previous owner.
It does a good job of cooling but the evap box under the dash sweats and drips.
It is NOT leaking.

50 on the low side and 225 on the high.
Blows 48 degrees at the vent on max.

I wonder if a more efficient condenser might help.
Click to expand...

At what RPM and what ambient temps? How much freon do you have in it? That seems like it is overcharged to me but my experience is in dry desert air. I fill it using subcool. A thermocouple on each side of the condenser then use an app where I type in the temps and pressures to give my superheat temp. I set it to about 10F degrees of superheat. That said the A Bodies I have done seem to like about 1.8-1.7 cans of R134A to get that superheat value. B Bodies about 2.8-2.9 cans. That ends up being quite a bit less than if you use the 80% less rule.
 
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Filled to pressures for 134a in my local temp of 95-ish per several charts I found including one here on FxBO.

Vent tube through firewall is not plugged.

It's condensation on the outside of the box.

Thoroughly checked several times to verify.
 
I even tried backing off the pressures/level of 134.

Backing down from 50/250 to 45-ish 220-225 raised temp at vent to 52-55-ish but did not stop or even lessen condensation.
 
Are you sure your expansion valve is working? Is it an aftermarket? If you pull the sense tube and move it from ice water to warm water do the pressures change? I have had zero luck with the Chinese aftermarket.. they may work for a while but not long. I have NOS valve in all of mine.
 
Jim Kueneman said:
A ton of miss information about R134a out there. You don’t need new hoses, you don’t need a special front seal, you don’t need a new expansion valve. Flush the system including the compressor, add the correct amount of PAG or Ester oil, new orings, remove the EPR valve and run it. The PV curve is very close to R12 until you hit pressures over 200-250 PSI and I would run the charge on the low side to not hit these pressures anyway. In my dry climate I don’t worry too much about freezing up but if the factory did not have a evaporator freeze up switch one should be added. The A Bodies seem to have one. B Bodies maybe not so much.

My 68 Coronet will freeze you out with R134a.

My 72 Duster with R134a (with a retro fitted 73 Dart AC box) works poorly. I have spent a fortune trying to understand why. I recently discovered that the 73 AC box is less than a one year design. It was changed again in 74 and stayed till 75 and the end of these A bodies. I am at the point in my troubleshooting that it was in the box. Plan to install the 74+ box (evaporator) this summer. It is starting to feel like the 73 design sucks. Note it is obvious in the pressures. The low side is just too low all the time. The superheat across the evaporator is WAY WAY to high and nothing changes it. It seems like that evaporator design was just not right and I hope it is fixed in the 74+ box.

66 Valiant I just finished with factory AC system and R134a appears to be working as well as the Coronet but time tell after the first 90+ day.

These are all build from NOS seals and valves.

Jim
Click to expand...
Jim,

What years have EPR valves? That is something I am not familiar with. Where is it located?

thanks
 
Mike69cuda said:
Jim,

What years have EPR valves? That is something I am not familiar with. Where is it located?

thanks
Click to expand...


It is stuffed in the compressor behind the suction line. Most have been discarded if the car had it replaced in the last 15 years. If you look in that port and all you see is a cavity it’s gone.
 
Thanks for all the great info here folks. The car I’m getting has factory air and I have tons of R12 saved from over the years. I will not convert it to r-134. I will leave it stock. Glad to know they work well. Air conditioning is important out here.
 
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