jackhild59

iTrader: (7)

Many of the replacements, including R134a and even the HC stuff will 'work' in a mild climate. That's why you also see the Canuks insisting 134a is fine. Add real heat, add lots of humidty and things change. The load on a system increases tremendously. Then you find out if the system has the heat moving capacity to handle the load. Not many places have the combination of heat and humidity that you find in the deep south. Add the *highest* temp of the day to the *lowest* RH of the day and you get an index that will help understand the effect true heat load on an auto a/c system. In my environment, Dallas TX, we often have heat+humidty that is in the 160-180 range. In AZ, you can have 120* with 5%-10% humidity. don't get me wrong, that is hot, but without the latent load (humidty) the a/c doesn't work nearly as hard as in Dallas, or Atlanta on a 95* day with 55% RH.

Innovation is in FL, where it is 79* +35% rh =114 right now.
Dallas tx is 72* +60% rh=132 right now.
Phoenix iss 78*+26% rh=104 right now.

Anything replacement will work at low index numbers. changing the refrigerant alwaYS changes the system capacity. Freeze12 does a great job compared to some other replacements. If you cannot get R12, Freeze12 is the very next best choice.

Rex7Vert

Has anyone done any real world comparisons performance-wise between using R134A and Freeze 12 in their RX7's? I have been reading a lot of positive comments regarding Freeze 12 and am very curious. I converted my 88 convertible last year to R134A and I am overall pretty satisfied (at low to moderate loads the compressor cycles and vent temp can dip into the 30's), but I do wish it had more capacity when it's really hot out. I live in Miami and we are already hitting 90 during the day and the humidity can easily climb into the 90% + range during the summer. By the way, I replaced the compressor (old one had a leak), replaced the expansion valve and drier, changed out the fan clutch, added an electric cooling fan and installed a parallel flow condenser. I tried HC-12a (hydrocarbon based) and was dissatisfied with it. The pressures were lower than those of R134a, which was good, but the system performed terribly at idle. As others have mentioned, this type of refrigerant might be OK up north in the milder climates, but definitely not where I live. I am still not happy with the hot liquid line from the condenser to the expansion valve and am hoping that a change to Freeze 12 will decrease that temperature and improve system performance further.

Sorry for the long post. Any comments would be most appreciated!

88 rex turboII

well how much do you guys get r12 for? i live in a border town and i just went to mexico and they sell r12 for 10 bucks a can and the oil for $8.almost for the same price of 134a.so i think im just going to settle for r12 for now and try it out.do you guys know any kind of wrap i can put on the a/c lines cuz my turbo sits so close and i dont want to mess anything up.

Dinnercoat

Hell if its actually r12 I'll pay you to send me some to recharge my system. =P

88 rex turboII

im pretty sure it is cuz they actually sell r134a for more cause the r12 is old to them.well see what happens this wkend when i get paid.ill just have to risk crossing it back cause its illegal to bring it to the states.

Dinnercoat

Is it just illegal to carry r12 or any kind of item like that?

Was going to say bring some r134 labels with you and slap them on the r12 when you come back. =P

jackhild59

iTrader: (7)

Your conditions are exactly the reason to avoid R134a or HC's. You spent all the money and it still isn't good. There is no guarentee that you will be happy with your system containing R12 either, but you can be sure that is operating at it's design capacity, maybe a little better with your upgrades.

Here is a lab test report, about as fair and real world as can be made.

http://www.ackits.com/testresults/alttest.pdf

Note that the 134a high pressures are significantly higher, from 40 to 100+psi higher. That sucks. Let me restate this in another way. That REALLY SUCKS. Also don't focus on vent temperature too much. Look mainly at the high pressure data and think about the pumping horsepower that it takes to run your system at 371 psi, over 107 psi higher than R12 and 89 psi over Freeze12.

I will now reveal my source of R12 to you all...........




Are you ready?


Yes, you have to pass your 609 MVAC Certification. It is an open book test. It is really not that hard. If you cannot pass this test, you shouldn't be working on A/C.....




Prices and company names?















NAPA $25 per 12 oz can.

Oriellies, $35 per 12 oz can. These guys wanted to know NAPA's price so they could match it.

I just bought 10 cans on EBAY with the average including shipping of $24 per can.

There seems to be plenty of old stock around. This seems to be the market, at least right now.

I know this is not cheap cheap, but if you fix your leaks or problems, the freon does not wear out.

AT this price, why screw with 134a or Freeze12 or HC blends or anything else? 134a is at $8-$10 per pound. Also, it is getting hard to find pure 134a. Everyone wants to sell you 134a with magic stuff added, leak sealer, o-ring conditioner, cooling enhancer and other hope-in-a-can bullshit that does not belong in your a/c system.

Anyone pricing R12 at higher prices is probably not selling very much of it.

jackhild59

iTrader: (7)

You did everything right. I bet you spent a couple of hundred? Maybe more? A typical 134a story...


What you are looking for is subcooling. This is measures as number of degrees the hot liquid refrigerant is cooled below the temperature at which the refrigerant is changing from vapor back to liquid (condensing).

That line will probably always be warm to hot. It must be at least warmer than the ambient temp, of course. Once you condense the refrigerant, the vast majority of the heat has been rejected by the system. It adds little capacity for the system to have the ability to subcool the liquid very much.

You already have the parallel flow condenser, you have spent the money for some additional capacity. So in your case, you will attain some subcooling and therefore some additional capacity if you revert to R12. I would expect Freeze 12 to perform fine in this system as well.

Good luck

Innovation

iTrader: (1)

Thanks for all the replies and advice. I solved the cooling issue by flushing the rad and I replaced the water pump because it was so old. I replaced the thermostat and both caps with OEM. I let the rad soak overnight in CLR (calcium, lime and rust remover) A lot of crap came out.
As for the A/C issue I went with freeze12. I bought a complete replacement kit at Freeze. com for 70 bucks. I replaced the accumulator because it is 19 years old. Evacted the system to -28 for and hour and recharged it with 3oz. of ester lubricant and two cans of freeze12. The vent temp. now is 44 degrees.
It's nice to be cool again!

Rex7Vert

Glad you got your problem solved Innovation. I just ordered FR-12 as well. Based on the great info we received from jackhild59, I think it may just be the ticket for me too. With all the changes I have already made and considering my system works pretty well already, I should be in good shape. Plus, it should increase the life of the components in the A/C due to the lower head pressures.

Great forum!!!

88 rex turboII

so whats the difference with freeze12 and r12? and which one did our cars come with?

Rex7Vert

Our cars originally used R12, which is no longer produced due to damage it produces in the ozone layer when it is released into the atmosphere. Freeze 12 is a blend of what cars are now using (R134a) and R22, which is what we use in our homes. The blend is supposed to do a better job of carrying the oil back to the compressor (although you do have to add a small amount of ester oil into the system presumably because the R134a component is not miscible with the mineral oil that the old systems used). Also, the blend more closely approximates the temperature-pressure relationship of R12 than R134a does alone, which should help keep head pressures to a reasonable level.

Innovation

iTrader: (1)

Sorry I didn't answer your question about how I measured the rad temp. I used a lasor reader we have at work. You point it at the device you want to measure and it gives an accurate read out. I pointed it at the top of the rad after a run with and without the A/C running. Without A/C kept at a constant
212 degrees and with the A/C running it was still at 212degrees.
I measured it after all the work I did and it is now at 185, with A/C or not.