Updating AC

Racingsnake

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I've got a '68 Fury a/c car that I would like to update to a R134 and a newer lighter compressor like a Sanden or similar. How much else do I need to change? Can I switch compressor, put a new receiver/dryer in and get new hoses made up and leave everything else standard or is it more involved than that? What compressor and mounting brackets have people here used and would they recommend them?(looking for big block brackets as I will be swapping out the 318) Finally, what is the round black thing on the inner fender here?
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I've got a '68 Fury a/c car that I would like to update to a R134 and a newer lighter compressor like a Sanden or similar. How much else do I need to change? Can I switch compressor, put a new receiver/dryer in and get new hoses made up and leave everything else standard or is it more involved than that? What compressor and mounting brackets have people here used and would they recommend them?(looking for big block brackets as I will be swapping out the 318) Finally, what is the round black thing on the inner fender here?View attachment 448478
People will chime in on what you can do regarding replacing the compressor. IIRC, you will need to replace the seals for R-12 aren’t compatible with R-134a.
The big black thing on the inner fender is a receiver / dryer, I believe.
 
I did the conversion you are describing on my 66 Monaco wagon. Mine was a bit more complicated because it has dual air but basically the same. The key is whether your old system is still sealed and if your evaporator and underdash parts are all good. My conversion worked quite well, you can read the thread at: 66 Monaco Wagon A/C Resurrection | For C Bodies Only Classic Mopar Forum
 
I don't recall ever seeing that thing mounted on your inner fender but I don't think it is the dryer. (maybe a muffler of sorts) but in addition to all you mentioned for updates, I would include the expansion valve. (located at the firewall)
If it were me, I would get the new compressor and brackets mounted, Buy a new dryer and expansion valve, then have an experienced A/C shop replace the hoses, test the evaporator and condenser, evacuate the system and charge with the 134. They may want to replace the condenser too.
 
Thanks for the replies. TxDon, I’ll have read through of your thread.
Sixpactogo, 3175375, how much worse is performance if the condenser is not replaced?
 
Thanks for the replies. TxDon, I’ll have read through of your thread.
Sixpactogo, 3175375, how much worse is performance if the condenser is not replaced?
I don’t know. The issue with R-134a is that you MUST have the charge right. If not, performance falls off dramatically.
R-12 is much more forgiving regarding charge amount.
 
Also keep in mind that as part of the conversion to R-134a, all of the old refrigerant oil must be removed from the system. The mineral oil used in R-12 systems turns into something approaching Gorilla snot when exposed to R-134a. R-134a is a significantly less dense refrigerant that tends to leak out more readily. Replacing all of the o-ring seals with the high density green o-rings is a must. You will already have to replace the hose set to use the Sanden compressor. Replacing the condenser with a unit designed for R-134a will improve the performance of the system as R-134a being less dense needs more condenser surface area to properly cycle the refrigerant. The object mounted to the fender well is a muffler. This device was used with R-12 to keep liquid refrigerant from being ingested by the reciprocating compressor. Liquid refrigerant causes "hammering" when it gets into the piston bores. The muffler is not needed for the conversion to a Sanden compressor.

Dave
 
My 68 wagon still has the factory a/c system that works and mine does not have anything looking like the object mounted to the fender well. My car is a early bid Nov 67. Maybe it was something added to later built cars.
 
From what I remember from back then, that larger muffler was only on 318s, not on B/RB engined-C-bodies back then. The 383/440 RV2 compressor line had a small muffler in it, close to the compressor.

R-134a does need more condenser size to work well. The condensers on the first-gen LH cars was wider than the radiator on those cars, for example. It's also been noted that a "mass flow" condenser works better than trying to use the R-12 "serpentine" condensers.

Start with about 10% less R-134a charge than the stated R-12 charge, then adjust from there for the best cooling, from what has been noted in the earlier days of R-134a conversions. Too much R-134a charge and cooling performance is not good.

Enjoy!
CBODY67
 
The fender mount muffler was larger because of where it was mounted. Big blocks had the muffler mounted above the engine where it was exposed to a lot more heat that boiled off most of the liquid refrigerant in the return line. The 318 cars did not have enough room to do that so a larger unit was mounted on the fender well.

Dave
 
Thanks for the replies, I’ll be getting a new condenser too. What is the reason for changing the expansion valve - do they go bad or what? Good to hear the muffler on the inner fender isn’t need, I’ll be glad to get rid of that. Read through TxDon’s thread and a couple that were linked to it which were very helpful. Think I’ve got a pretty good idea what's needed now.
 
Thanks for the replies, I’ll be getting a new condenser too. What is the reason for changing the expansion valve - do they go bad or what? Good to hear the muffler on the inner fender isn’t need, I’ll be glad to get rid of that. Read through TxDon’s thread and a couple that were linked to it which were very helpful. Think I’ve got a pretty good idea what's needed now.

The system will still work with the R-12 expansion valve, but it won't be quite as efficient. Given that you are going to have to tear the system apart, this would be a good time to replace the expansion valve as it is now over 50 years old. These valves were pretty reliable in their day but if the system was left discharged for a long time, they will often stick and quit functioning. Be careful taking the old valve loose if you choose to replace it so the you do not damage the evaporator. The threads sometimes will be seized and you can twist off the inlet for the evaporator. A little heat from a propane torch will usually free up the threads, but do not over do the heat.

Dave
 
The muffler was there to smooooth out the gas flow through the system. The compressor output will have pressure pulses due to how it operates, especially at lower compressor rpm.

When my '77 Camaro was newer, one spring day I turned the a/c on for the first time in a/c mode and at certain engine rpms, got a new harmonic vibration that seemed to be coming from behind the instrument panel. Only with the compressor running. Diagnosis indicated that it was due to the fact that that factory a/c system had no muffler in it, BUT the more upscale Firebird models DID. As did almost every other GM factory a/c system, but not Camaros.

So, the shop foreman advised of an auto supply to go to get the needed muffler and clamps, which I did. I'd already looked at the Delco A/C Illustrated Parts catalog for information. Got the new muffler installed and all was quiet again.

That was with the GM A-6 (6-piston) compressor that generally operated very smooth and quiet. Obviously with more even pressure spikes (or less intense) pressure spikes than either the Chrysler RV-2 or Ford Tecumseh 2-piston (BIG piston, by comparison) compressors. I suspect the newer-design Sandens might operate smoother than the older compressors?

It could be that the receiver/drier might act as something of a "muffler", but maybe not, depending upon its placement in the gas flow system? Once everything is installed, might be a good idea to design-in a length of hose (compressor output) where a small muffler might be installed later on?

Enjoy!
CBODY67
 
The muffler was there to smooooth out the gas flow through the system. The compressor output will have pressure pulses due to how it operates, especially at lower compressor rpm.

When my '77 Camaro was newer, one spring day I turned the a/c on for the first time in a/c mode and at certain engine rpms, got a new harmonic vibration that seemed to be coming from behind the instrument panel. Only with the compressor running. Diagnosis indicated that it was due to the fact that that factory a/c system had no muffler in it, BUT the more upscale Firebird models DID. As did almost every other GM factory a/c system, but not Camaros.

So, the shop foreman advised of an auto supply to go to get the needed muffler and clamps, which I did. I'd already looked at the Delco A/C Illustrated Parts catalog for information. Got the new muffler installed and all was quiet again.

That was with the GM A-6 (6-piston) compressor that generally operated very smooth and quiet. Obviously with more even pressure spikes (or less intense) pressure spikes than either the Chrysler RV-2 or Ford Tecumseh 2-piston (BIG piston, by comparison) compressors. I suspect the newer-design Sandens might operate smoother than the older compressors?

It could be that the receiver/drier might act as something of a "muffler", but maybe not, depending upon its placement in the gas flow system? Once everything is installed, might be a good idea to design-in a length of hose (compressor output) where a small muffler might be installed later on?

Enjoy!
CBODY67
I agree that a scroll compressor, like the Sanden, would be much smoother regarding pulsation of the refrigerant.
 
The system will still work with the R-12 expansion valve, but it won't be quite as efficient. Given that you are going to have to tear the system apart, this would be a good time to replace the expansion valve as it is now over 50 years old. These valves were pretty reliable in their day but if the system was left discharged for a long time, they will often stick and quit functioning. Be careful taking the old valve loose if you choose to replace it so the you do not damage the evaporator. The threads sometimes will be seized and you can twist off the inlet for the evaporator. A little heat from a propane torch will usually free up the threads, but do not over do the heat.

Dave
Thanks, that makes sense. I’ll add it to the list!
 
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