1966 Olds Toronado A/C

[Mikel]

Thank you guys.

I do have a sight glass in the dryer, but unfortunately it is buried out of sight behind the grille of the car (so much for serviceability).

My POA is set at around 32 PSI, so I suppose I could make that adjustment fairly easily. I did check it with compressed air before I put together the system. The problem is that temperatures now are in the mid 70s, so even my mediocre-performing A/C feels super cold.

I really would like to set the POA to 23 PSI and give R152A another try.

I will keep an eye on the weather forecast. If we have any hot days left this year, I may be doing some experimenting!

Thank you.

[Tom Greenleaf]

Ambient temps? It's a problem to KNOW for sure pressures and performance is right I'll say if lower than REAL 80-90F, that being the air thru the grille. Take into account surface you probably are on is colder now also a running car is getting that at it vs stuck in traffic on a no shade road.

This stops me for performance or really tweaking a system especially a retrofit. Another identical one may not be the same never mind fully an antique car.

So I suggest get close so oil moves and you feel high side heat and low side cool perhaps even sweating?

I don't wish to do it again but heated my shop (took all day) to 100F, wait for tools (lots of course) to also warm up do do a car that had an accident HERE was headed back to FL to 80s-90s the condenser new from collision so empty. Got it but not worth the cost to heat that hot in a shop I did just want to see if I could. Storage of R-134a also a consideration if too cold it won't dispense out on its own. Was hovering ZERO that day and windy.

Had to say that it was fun to succeed but you have the issue just try to stay on lower guess side if used as more cold comes I think even 1966 would kick on A/C for defrost setting to exercise it if on seconds. If not circulating oil it's killing itself you don't need that.

Subject to opinions and reasons + types of vehicles. I disable my compressors for Winter (too many vehicles) so they (old too) don't all need new compressors or more in Spring. So far so good all are OE original systems. Do not do that to electric fanned vehicles that are computer controlled turn on both by high pressure or hot enough engine coolant return can mess those up,

[Mikel]

Hopefully weather will cooperate in the next few weeks

[Tom Greenleaf]

Same here, rain and cool for a while. Was thinking about the sight glass. If you had or wanted to use one of those scopes, bendy line fits in spark plug holes shows on screen on device or real good ones records it. Harbor Freight has them if close by. It's not supposed to be useful for retrofits but interesting and was close for some I did from the 60s very small glass on some. If you do remember to raise idle up may be able to move "step cam" for cold idle on most carbs with automatic chokes I think this must have.
It's a side idea I do recall most raced high RPM with a touch of gas pedal or pull on rod/cable watch it trip choke. See the thing "the step cam" GM/Rochester Quadrajets or some other (Olds would play with others or changed out long ago all "Quads" were fussy to adjust or some said Spring and Fall turn choke heater a notch or two. Laugh, each so unique the owner knew how many pumps stone cold or not to if already warm perfectly if paying attention. No two alike exactly.

So hope for a warm to hot stretch it's still possible?

[Mikel]

I readjusted the POA today to 23 PSI. Will be trying R152A this weekend. Let's hope for some warm weather!

[Tom Greenleaf]

,Just watch center vent temps , subtract ~5F for what evap really is AND that it drips water. If not, that's too low. Hard to be sure this time of year of course,

[Cornbinder89]

That is the beauty of devices that control the evaporator temp by controlling the pressure, the refrigerant will not get colder than the boiling temp of the pressure selected. Unlike a frost switch, that can be "fooled" by how it is placed and where, if the refrigerant can't drop below a set boiling temp, neither will the evaporator fins.
The drawback is: every refrigerant has a different boiling pressure at 32 degs, so every change in refrigerant requires a different setting on the pressure regulation device.
The same system is used in commercial refrigeration when you have two evaporators that cool to different temps, like a refrigerator and a freezer, run on the same compressor and condenser. You use a thermostatic switch for the colder temp evaporator and a pressure regulator for the warmer one.
It is also good on engine driven devices when you don't want to clutch under load, the compressor runs continuous, but the evaporator never drops below the setpoint. Auto A/C started getting away from it when fuel economy became more important than A/C component life in the 70's.

[Mikel]

Good morning.
I charged approximately 30oz of R152A and I get 42 deg vent air at HIGH fan speed. Pressures are 23-24 PSI low, 160 PSI high. 65 deg ambient temp.

Tomorrow supposedly we will be in the upper 70s. Will get more measurements and see if it's dripping water.

Thank you.

[Tom Greenleaf]

Bit cool out but that's impressive still. Keep an eye on it for REAL air temps, right where you are as it comes in thru grille. Dripping to me just proves it's not freezing up anywhere also depends on dew point/humidity of the day or area you're working. Already said if 30oz checks out for assorted conditions definitely mark that down under the hood,

[Cornbinder89]

Good morning.
I charged approximately 30oz of R152A and I get 42 deg vent air at HIGH fan speed. Pressures are 23-24 PSI low, 160 PSI high. 65 deg ambient temp.

Tomorrow supposedly we will be in the upper 70s. Will get more measurements and see if it's dripping water.

Thank you.

30 oz sounds like a lot. I thought I read somewhere that like 134a when you change to 152a from R12 it takes less by weight. I can't find where I saw that, but you might want to double check the amount needed. Might take a little trial and error to get it dialed in.

[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.