1966 Olds Toronado A/C

[Cornbinder89]

Yeah, that is what it should be for R12. Your question is a valid one, just no way to answer it. That is another problem with these "so called" Drop in replacements for R12, they don't always work and cause more problems than they solve. At least if you are running one refrigerant you can come up with settting based on that one refrigerant. There are some mixes, that the chemicals homogenize and have one set of pressure/temps for the mix, and these mixes are given their own R number
My understanding of Duracool, is it has just enough R290 to move the refrigerant oil around the system with the R134a, which is the primary refrigerant and makes up most of the mix. Given that, I'd try a POA setting close to that of R134a, but if you have to go through all that, why not just run 100% R134a and be done with it?

[Tom Greenleaf]

Mikel > Sorry about a notice of a reply or 2 I/we have to remove butt heads advertising on YOUR thread. While here, the cold is here no surprises now impossible to know A/C works well when needed. Was slow all season all the assorted reasons. Shops are jammed weeks to get a vehicle fixed for some things A/C wouldn't have been a priority if the vehicle was usable!

[Mikel]

Hello,
So finally we had some warm-ish weather and got a chance to test it.

At 80 degrees pressures were 30/180PSI. Once the car is moving, it cools quite adequately (I would estimate mid 40s), but at a stop it doesn't nearly as well.

In my '66 Oldsmobile, the condenser is about 3/4" away from the radiator (which has a very powerful mechanical fan behind it), with open sides, so most of the air sucked by the mechanical fan goes around the condenser. Touching the inlet and outlet lines to the condenser, there is not a big temperature drop.

I'm going to see if I can place something to close those gaps around the condenser.

I have heard that old style linear condensers don't work well with R134A, not being as efficient as modern parallel types. I wonder if this also applies to R152A.

Thanks.

[Cornbinder89]

What do you have the POA set too? I thought previously you had re set to 23 for R152a? You are off the grid so to speak, so you may have to experiment a bit. I would guess it would be better with a parallel flow condenser.
The lower the suction pressure the less volume of refrigerant on each intake stroke of the compressor. You might have to change the pulley ratio to speed up the compressor a bit.
I try the parallel condenser 1st, it stands to reason that if it takes less by weight like 134a it too would benefit from a better condenser as well, just like 134a does.

[Mikel]

I'm using a different set of gauges. I will have to confirm my readings. But no, I haven't touched the POA valve.

I may install a solenoid to raise the idle when the A/C is on.

Thanks.

[Cornbinder89]

So, what is it set too? If 30 psi that is why you have poor cooling.

[Mikel]

I will get another set of gauges and confirm.

[Cornbinder89]

I am fairly sure I mentioned this before, but bares mentioning again. Dust-Off cans are marketed to blow dust off things. There is no reason after the required amount of 152a is in the can that air cannot fill the rest of the can, for the purpose of blowing dust off, it makes no difference ,the R152a is just a propellent. Just like a potato chip bag contains air that is not listed on the "contents" a dust-off can could also with no ill effects for the marketed use of the can.
Refrigerant, marketed for refrigerant purpose must be air free. With cans marketed for other purposes you have no way to know if there are non-condensable gas in the can also. In small amounts air will raise the pressures in the system and make for poor cooling, in large amounts you'll get no cooling.
To be sure that the can you are buying has R152a and nothing else in the can, you need refrigerant grade containers of R152a, unfortunately, I can't find anyone supplying it that way in smaller containers in the US.
This can leave you fighting poor cooling, changing amounts and condensers, all to try and overcome a none compressible gas problem caused by the packaging you are using to get the 152a, that was never supposed to be used in refrigeration.
Just something to keep in mind.

[Cusser]

Hello,
Once the car is moving, it cools quite adequately (I would estimate mid 40s), but at a stop it doesn't nearly as well.

In my '66 Oldsmobile, the condenser is about 3/4" away from the radiator (which has a very powerful mechanical fan behind it), with open sides, so most of the air sucked by the mechanical fan goes around the condenser.

I'm going to see if I can place something to close those gaps around the condenser.

Yes, I would fabricate some type of shroud to direct cooling air through the condenser.

[Mikel]

I am fairly sure I mentioned this before, but bares mentioning again. Dust-Off cans are marketed to blow dust off things. There is no reason after the required amount of 152a is in the can that air cannot fill the rest of the can, for the purpose of blowing dust off, it makes no difference ,the R152a is just a propellent. Just like a potato chip bag contains air that is not listed on the "contents" a dust-off can could also with no ill effects for the marketed use of the can.
Refrigerant, marketed for refrigerant purpose must be air free. With cans marketed for other purposes you have no way to know if there are non-condensable gas in the can also. In small amounts air will raise the pressures in the system and make for poor cooling, in large amounts you'll get no cooling.
To be sure that the can you are buying has R152a and nothing else in the can, you need refrigerant grade containers of R152a, unfortunately, I can't find anyone supplying it that way in smaller containers in the US.
This can leave you fighting poor cooling, changing amounts and condensers, all to try and overcome a none compressible gas problem caused by the packaging you are using to get the 152a, that was never supposed to be used in refrigeration.
Just something to keep in mind.

Yes, that is a very valid point. Thank you.

[Mikel]

Yes, I would fabricate some type of shroud to direct cooling air through the condenser.

I did fill those gaps around the condenser with foam and now I get much more air flow thorough the condenser while at a stop. The difference in cooling performance between engine idling at a stop and vehicle moving has largely gone away.

[Mikel]

I am fairly sure I mentioned this before, but bares mentioning again. Dust-Off cans are marketed to blow dust off things. There is no reason after the required amount of 152a is in the can that air cannot fill the rest of the can, for the purpose of blowing dust off, it makes no difference ,the R152a is just a propellent. Just like a potato chip bag contains air that is not listed on the "contents" a dust-off can could also with no ill effects for the marketed use of the can.
Refrigerant, marketed for refrigerant purpose must be air free. With cans marketed for other purposes you have no way to know if there are non-condensable gas in the can also. In small amounts air will raise the pressures in the system and make for poor cooling, in large amounts you'll get no cooling.
To be sure that the can you are buying has R152a and nothing else in the can, you need refrigerant grade containers of R152a, unfortunately, I can't find anyone supplying it that way in smaller containers in the US.
This can leave you fighting poor cooling, changing amounts and condensers, all to try and overcome a none compressible gas problem caused by the packaging you are using to get the 152a, that was never supposed to be used in refrigeration.
Just something to keep in mind.

Gave this a bit more thought. Cans for refrigerant use must be purged before filling, which costs money. With cans that are destined to be keyboard duster, would the manufacturer bother with this extra step? I suppose the answer is no.

[Cornbinder89]

It is more that you can't fill 100% to the top. Like a propane tank, you can only fill 80% or less to allow for expansion/vapor pressure. I just don't know how Dust-off cans are mfg and packaged. they may be made how refrigerant cans are, or they may be packaged with air in the remaining space.
I just don't know how the packaging is done.

[Mikel]

We've had some days in the 80s. Vent temperatures in the medium fan setting are in the mid 40s. Not spectacular, but quite adequate. Will report again when it gets warmer.

[Tom Greenleaf]

Oh Mikel: I've missed a lot forgive I don't get notices from here??
Back a few if this is a Quadrajet soon after this was new they did make an electric solenoid on carbs, driver's side would click to higher idle you mentioned but not without you touching the gas pedal idea was when no power to it, it would help stall the engine not to run on as if on lousy this would have called for 98+ octane I think.

IF you could hunt that down it would fit this just enable it for when A/C is on just cover the load before that idle speeds were different A/C on or off.

Oh me I know they did that into the 1980s.

Mid 40sF you said is about right high end cars were NOT meant to freeze you out more than others but rather volumes of air not colder.

IDK who alive anymore would recall that try if you still want to do that bet you can with OE parts for Rochester Quadrajets. If not that for 1966 forget that IDK what was done but many assorted cars covered loads A/C the most.

Owned the Rocket 455 was a Nighty Eight didn't say that just the "LS" top dog car was a 1968. Just that know it was thought of that long ago.

Other is wail the fan and fan clutch this might not have had one rather a 5 blade fan was noisy you could add one for just some newer than this if not OE to this being the first of a new vintage,

[Cornbinder89]

For the third or 4th time, what is the POA set too? You have not provided a psi reading on the POA setting. The POA determines evaporator temp. Without that info everything else is guesswork.

[Mikel]

My low side is at about 27 PSI.

RPM is about 800.

[Cornbinder89]

That isn't what I am asking, I want to know what pressure the POA is set too? You have to set it off the system, most use air pressure or dry N2 to set the valve. IT MUST BE SET for the refrigerant used. This has little to do with what the low side pressure is. Goggle setting a POA for a video on setting the POA.
The POA sets how cold the system will get, unless you get that right, it will never cool properly.
Most newer system use a frost switch to turn off the compressor when the evaporator temp approaches the freezing point, Systems with evaporator pressure regulation, control via pressure, if it isn't set to the temp/pressure of the refrigerant used, it will either frost over or keep the evaporator too warm.
On this systems the compressor stays on all the time.

[Mikel]

Last time I had it out I set it at 23PSI with compressed air.

[Cornbinder89]

Thankyou, that what was I was asking. If you are sure that is where it is at, we can rule it out as the cause of the higher than ideal vent temp. I would look at the condenser next and take readings (or even use your hand) to check that the refrigerant is shedding its heat. baffling so more air goes through can help. But like R134a R152a may benefit from a parallel flow condenser. Misting the condenser with water is another way to temporarily make it more efficient, to see if that is the problem.
As I said before, you are off "in the weeds: doing an experiment that is going to take some time to sort out, there are no "text book" answers, and few have gone down this road, and those that have haven't published what they found.
It may turn out that the lower density of the refrigerant makes it so the whole system need to be larger to move the same heat load. Good note taking and readings to see what heat is being moved would help point to trouble areas.
I found that R134a was close enough to R12 that the difference in performance could be mitigated by increasing the condenser. That may help or it may not be enough with R152a, The operating pressure and the density are further fromR12's than R134a is.
Looking at condensing temp/pressure, and low side pressure might give an indication that there is some non-condensable (air or other gas) that is in the dust-off cans and are causing a problem.
Like you, I am not an engineer so don't know how to look at the data and be able to tell you what needs to change to move the same heat load with the new refrigerant. Like you, I can only do "seat of the pants" guesses, and then look at the results, and make adjustments from there.
Again, I wonder why "powers that be" started down the road to use R152a and then abandoned it in favor of R1234yf? It might have been flammability or it might have been they had to totally redesign the systems, enlarging components to the point they wouldn't fit well in an automotive environment.
On the systems I have, R134a works and I have enough supply to last if it becomes not cost effective to recharge for the foreseeable future, but if things change I would take a hard look at R152a and what you find out today.
The pressure/temperature chart posted elsewhere on this site .for R152a is going to be useful in finding where the problem areas are.