A/C condensor replacement

I took the Criterion in yesterday to have the front end fixed. This shop is 70 miles south and the same folks who did my A/C repairs. It was 96 degrees here so the A/C struggled to keep me comfortable.
I was talking to the guy about replacing my compressor to a modern one to better cool since I'm using 134-a freon. He tells me it's not the compressor that would need replacement but the condensor. He claims the r-12 condensors do not exchange the heat as well with the 134-a freon in them.
Has anyone heard this before?
 
Yes, I have. The whole system doesn't work as well with R134 in it as it would work with R12 in it. Refrigeration systems are designed around the refrigerant, and when you change the type of refrigerant that it was designed for, you change all sorts of performance dynamics. Systems designed for R12 don't work very well with R134. Unfortunately, now you are between a rock and a hard place, since once you converted to R134, the only way that you can convert back to R12 is to replace the components that have been modified to accept the R134.... i.e. the charge and test fittings. The sweetness of the lower cost of R134 is offset by the bitterness of poor performance. The cost of upgrading the condenser is going to be a lot more than the cost of R12. I still can't believe / understand that there is no one in a 70 mile radius of where you live that has the equipment to install R12.
 
I find it hard to believe as well but, I called eveyone and no one would touch it. I talked with a local A/C company and they can change it from 134-a back to r-12 by replacing the oil and changing the drier then fill it up. About $400 to do it.
Back to original question, "Has anyone heard that replacing the condensor will make a converted system cool better? Keep in mind, with temps at 96 degrees, driving down the expressway and warm air coming in through the wheel wells, not sure any system will freeze you out. I was not uncomfortable but would like it cooler and if replacing the condensor will do that, then I would or am I getting a story.
Trust me, anything is better than nothing at all. :snow_smi:
 
having been in that rock I understand how you get there. but one of the new ones listed on e-bay are not that expensive and are a newer type exchanger. but what I would do is quit listening to other people. you have the system cooling and let it go. if you replace the 10,000 small holes and weather seals in the car you might just discover it cools better. I don't remember any system in 74 that would cool like the ones in a new car. first off look at the difference in what your cooling. also did you have the rear AC unit running. always have the rear ac running at lest on low fan to keep the system from freezing up. then take it back to the man that worked on it. you have had it long enough so that some may have leaked out and now it's not as efficient as it could be.
 
having been in that rock I understand how you get there. but one of the new ones listed on e-bay are not that expensive and are a newer type exchanger. but what I would do is quit listening to other people. you have the system cooling and let it go. if you replace the 10,000 small holes and weather seals in the car you might just discover it cools better. I don't remember any system in 74 that would cool like the ones in a new car. first off look at the difference in what your cooling. also did you have the rear AC unit running. always have the rear ac running at lest on low fan to keep the system from freezing up. then take it back to the man that worked on it. you have had it long enough so that some may have leaked out and now it's not as efficient as it could be.

When Terri and I drove it to Danny's place in Georgia, we closed the partition door off so we were cooling the front which was nice. I didn't do that yesterday. Even though the rear unit stays on all the time and cools respectively, having the entire car open at 96 degrees, it was doing all it could do.
When I pick the car up later this week, I'll close the partition and see how that is when driving home. Last Saturday is was just as hot and it cooled just fine when attending the car show.

:whip:
 
There is virtually no insulation in the body like there is in a GM factory built car, so this will also be part of the problem. When I was working on my Chrysler, I removed the front seat and installed a 1/4" reflective shield under the carpet. It did a lot to reduce the heat from the exhaust system that runs under the floor. When I start on the restoration of the headliner on the 1969, I intend to use a new "space age" insulation that is adhered to the underside of the roof prior to installing the new headliner. I did find that Miller Meteor used a 1" thick fiberglass bat type of insulation in the roof, but is isn't of much value, when you have the sun beating down on that large expanse of metal.
 
Yes, I have heard of it... If you recall, when this thread originally aired, I strongly encouraged keeping the unit as designed... When you did the conversion, did you have the POA valve recalibrated, or did they just flush the system and change the fittings?

It's a bit of a drive, but call the folks at classic auto air in Tampa. They will tell you everything you ever wanted to know. (and even a few things you don't)
 
Yes, I have heard of it... If you recall, when this thread originally aired, I strongly encouraged keeping the unit as designed... When you did the conversion, did you have the POA valve recalibrated, or did they just flush the system and change the fittings?

It's a bit of a drive, but call the folks at classic auto air in Tampa. They will tell you everything you ever wanted to know. (and even a few things you don't)

They changed it and the schrader valves, drained the compressor oil and changed it, then ran a dye check and pressure checked the system, then charged it. It has done very well but we all know 134-a will not cool as well as r-12 in an old system.

I'll keep you informed. On the Lifeliner, I'm leaning towards just putting a new A/C system in all together.
 
take it back to the man that recharged the system. if it has a slow leak you have used it enough to have it now show up. they may be able to find it or add a can of sealant and a little more 134. give the man a chance to fix the system first before you start changing things around. that's a long hose to the rear of that car. the 134 will work same as the freeze 12. these guys said they can fix it, give them the opportunity to. it should put out air at or under 38 deg from the vents. if it's not the system is low. if it is you got all you can get no matter what you change.
 
take it back to the man that recharged the system. if it has a slow leak you have used it enough to have it now show up. they may be able to find it or add a can of sealant and a little more 134. give the man a chance to fix the system first before you start changing things around. that's a long hose to the rear of that car. the 134 will work same as the freeze 12. these guys said they can fix it, give them the opportunity to. it should put out air at or under 38 deg from the vents. if it's not the system is low. if it is you got all you can get no matter what you change.

How about another class while in Albany? "134-a Freon Class with Ed" It is back at their shop and they will look at it just to be safe while they work on the front end.
 
I picked the Criterion up this afternoon and what a difference now that the center drag link and idler arm have been replaced. I can drive the speed limit on the expressway now-Yeah!
The A/C was re-checked and was still fully charged. Driving it home I closed the partition door and with temps hitting a heat index of 110 degrees, it was comfortable.
Albany bound in a little over 4 weeks. :bonk:
 
Ok, with all this A/C talk I to have a A/C question. On a compressor replacment and if your running R-12 or Freeze 12 in your system can you buy a new or rebuilt compressor and put R-12 or Freeze 12 back in the system after you have replaced the compressor or do you have to up grade the system to R-134?
 
the GM rotary compressor that fits the 70 cars are around a 100 dollar investment. new it is ready to put in any brand of coolant you want. the freeze 12 is either propane or natural gas one of them boom if you light it ones. the only advantage with the freon is it doses not explode. but the compressor does not care what it pumps. the newer ones are a little more efficient in a smaller system. were the coolant comes into play is the orifices that allow it to expand. there is a difference between the 12 and the 134 due to the make up of the gases. I still don't have all of that understood. but for my money if it was designed to have r 12 in it it will work with r12 in it. the problem is finding some one that is willing to do it. I have a man here now that will do either one . you buy the gas off from e-bay and take it into him and the price for putting it in is the same.
 
My experiences

Hi Richard! I have substantial automotive air conditioning experience and having read most of the posts here, everyone is making good points. Perhaps the three I'd like to emphasize are these:

1) Paul is correct. The physical characteristics of R-134a are that it requires a larger condenser to give equal condensing to the R-12 condenser. (The condenser takes the high-pressure, high-temperature refrigerant gas from the compressor and removes heat to change the refrigerant back to a liquid.)

Along the same lines, the molecule of R-134a is a smaller molecule than R-12. As such, special refrigerant hoses are necessary to keep the molecule from seeping out through the hose material. Typically, the hoses are made of Parflex.... more of a plastic than a rubber.

2) Our cars from that period are notorious leakers of air around doors, etc. Any leaks of incoming warm air will only work against the attempts of the a/c system to cool. Seal those leaks!

3) I have a '76 S&S hearse, and the a/c of the '75 would be the same. There are times that GM, much like Ford with their "better ideas" doesn't do the consumer any favors. To this day, even on modern cars, I deplore automatic air conditioning. Give me manual a/c of '63 and older ANY day. Most of the guts controlling the '75 system are located below the glove box and need to be set up correctly in order to give satisfactory results. Robinair even manufactured a diagnostic device to test vacuum and electronics of our cars ('74-'76). I've seen these on ebay, so keep an eye out. In short, the programmer senses interior temperature and tells a transducer to move a control arm in or out to control a damper, warmer-colder. It is possible that at max-cold setting, the arm, which is adjustable, is not fully extended (or retracted, I don't remember which) to give max-cooling. If the system is in otherwise good condition (full of refrigerant, etc) you can get on your knees on the passenger side, open the panel beneath the glove box, and see if the control arm is adjusted fully out (or in).

One last comment about the compressor. The GM A-6 compressor used on this car is a workhorse compressor used since 1962 and is a GREAT compressor, my personal favorite. They have 6 cylinders, great compression, an oil sump to keep the components lubricated, and are relatively inexpensive and still easily available. I would NEVER consider changing to an "updated" style compressor in my '76. I hope this helps. Tom

www.bippusautostorage.com/cars
 
Richard, Tom H. knows a LOT about this topic as that is his business! To expand a bit on one of his points: you probably know that the "max a/c" setting recirculates the cabin air rather than pulling in outside air. I'm sure this isn't a 100% situation, but on a hot day like we have here in the South, your system will operate better recirculating some cabin air than trying to cool 100% outside air that you're pulling in in regular a/c mode. I had read this in some article about improving engine efficiency a few years ago and it does make sense if you think about it. Pulling my boat boat down to the beach last weekend, I remembered this little fact and suddenly was much cooler and the compressor seemed to run less when I switched to the MAX a/c mode. Coming back from a quick trip last week, I was amazed at how FRIGID the airport parking shuttle bus was Friday at 1200 noon! I'm sure it was a 134 system and the driver must have been in recirc. mode. It was definitely over 90 outside. I'm at the beach on the annual family vacation and am supposed to pick up the '75 M-M Saturday :) After new tires, its next stop will be for a new A/C compressor and I'm going to have to read through all these a/c posts to find out what my options are. I already had to replace a leaking heater core which was not cheap! Can't wait to see the nearly completed project!
 
Yes, I have. The whole system doesn't work as well with R134 in it as it would work with R12 in it. Refrigeration systems are designed around the refrigerant, and when you change the type of refrigerant that it was designed for, you change all sorts of performance dynamics. Systems designed for R12 don't work very well with R134. Unfortunately, now you are between a rock and a hard place, since once you converted to R134, the only way that you can convert back to R12 is to replace the components that have been modified to accept the R134.... i.e. the charge and test fittings. The sweetness of the lower cost of R134 is offset by the bitterness of poor performance. The cost of upgrading the condenser is going to be a lot more than the cost of R12. I still can't believe / understand that there is no one in a 70 mile radius of where you live that has the equipment to install R12.




How much is your R-12 running per pound? I paid $93.00 per pound last year and then I went ahead and changed over last week to the 134 R. I added an electric pusher fan on the front and the newer coolent seems just fine I have 36 F degree air in out of the vents with an outside air temp of 96 F degrees.
 
How much is your R-12 running per pound? I paid $93.00 per pound last year and then I went ahead and changed over last week to the 134 R. I added an electric pusher fan on the front and the newer coolent seems just fine I have 36 F degree air in out of the vents with an outside air temp of 96 F degrees.


Tell me more about the pusher fan and how that is set up.
 
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