1966 Olds Toronado A/C

[Mikel]

Thank you both.

On the system being overcharged... This car requires 4 lbs of R12

[Tom Greenleaf]

Stay on the lower side IT'S PLAIN NOT HOT ENOUGH OUT - IMO of course. I knew the cars (owned many weren't old) took up to 5lbs of R-12. More than 1/2, even many luxo cars didn't have A/C at all was a credit option, even Cadillacs would do that of the GMs! I can't speak for Olds this car was the test with Eldorado in wait for 1967 as a FWD monster car, 2dr only.

Back to %s used? 134a I've seen 65-70% be perfect or best it could be. I only believe 152a would be 85% or so. Don't forget if you've replaced parts that are not exactly OE they should have or used to say on them (a card you could remove) lower OE capacity by "X" amount could be a lot. Especially condensers fat tubing you could fix those if you change it just to make the swap it would be faster to exchange heat but not take a pebble at highway speeds too well.

Look - is it really OE from new? It could be this long not the next.

Also (strong rumor) cars sold new came with 1lb too much to account for leakage expected (front seals) would work well up or down a pound!

Again, stay on the low side till it's really hot again, ground counts now is cool car is sucking in air right over that or watch something that harmlessly makes smoke a couple feet in front, hood closed for that observation,

[Mikel]

This weekend was a disappointment. At 75F, vent temp was 46F.

[Tom Greenleaf]

Not so fast to judge it - yet. It may be all it's controlled to do until warmer still? Is it still feeling hot lines off compressor and cool return? It also could have leaked a lot out or now finding it does want more refrigerant up to maybe WAG 85% if it's holding?

How to tell? Bubble test things where they connect. Next I'll try some 152a on a sniffer if it sets it off right now IDK never tried? If not I'd add a smidge of a gas that will sniff out and find leaks if any.

You may be starting all over when really warm with just getting the charge right, leaks ruins that info of course,

[Tom Greenleaf]

OK - My Matco AC 850, the most used sniffer I'm very used to DID WORK ON 152a, right away.
If not familiar with sniffers if like this one they will sniff out lots of gasses including propane, butane, R-12,22, 134a of course and anything used for cleaning solvents, smoke off engine parts (this car especially) just smears of oil or grease on hot engine parts till burned off totally. These don't like wind nor if you just cleaned a floor or used some paints real close by will fool you.

Setting for how large a leak range from ones you'd hear to ones that would be a gram per month or less so it will go off with something around.

It nor much else is proof positive of a leak it's good to also use a dye you can plain see or UV light type most are both. Leaks are expected it's just how fast is so hard to know.

High pressure now the better (engine off but warmed up helps and A/C run too) pressure is higher. Some leaks hold vacuum but not pressure - know that.
Science trivia is ave. atmospheric pressure is about 14.7 PSI so holding a vacuum for hours only means it seals out that much pressure not possible 200 PSI or lots more. Moral is don't be fooled by a well held vacuum that you don't leak.

Check the fittings too a common reason out of the gate for a retrofit, bubble test like a tire,

[Mikel]

Good morning.
I didn't plug the gauges yesterday, since I lose some refrigerant everytime I do so. I will try again next weekend.

I would think a leak large enough to make itself noticeable in two days should be easy to detect. I do have some UV dye in the oil and I have a Harbor Freight R134A sniffer.

Will update with any findings.

Thank you.

[Tom Greenleaf]

If you do it should be simple? It happens if so better now so you know,

[Mikel]

Still works and no traces of large leaks. But no warm weather yet.

On a slightly different topic - A friend has the same car, a '66 Toronado. He tried Duracool (mostly propane, I believe). In a mid 80s day, it blows in the high 40s. What's the proper POA setting for this refrigerant?

Thanks.

[Cornbinder89]

As I understand it, it is a mixture of 134a and R290 (propane) R 134a is around 26 @32 deg F and R290 54 psi @ 32. SO what to you set it at? I have no idea!
I think it would depend on the what the mixture is.

[Mikel]

Factory POA setting is 32 PSI. Thanks.

[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?