wanted: someone who can work on a R12 system in College Station area.

[Macrobb]

And, it depends on the compressor. The compressors in the bricknose/bullnose trucks seem to be much more... sturdy than the newer ones in the OBS trucks. I've pulled a couple of siezed OBS units apart, and they absolutely depend on plenty of oil - it's literally sliding steel on aluminum to rotate. No oil(or not enough) = galling of the aluminum = dead compressor in very short order.
The older York-style compressors with their own oil sumps? Those, you don't need any oil in with the refrigerant, because it's a wet-sump compressor and the oil is "outside" of the refrigerant loop.

After all that, I charged up with HC-12 and never looked back. It's legal, works great, and I don't need a license so I can do as I please without any "interference". Heck, I'd even be tempted to try straight propane like one guy did a while back. Not likely now that everything works fine, but still, I can't help but wonder how well it could be made to work.

I'm not going to say that it can produce temps below freezing at the evaporator if you wish...

 

[DrCharles]

Sounds like you did it right, david85. The best move was the parallel-flow condenser. If you're starting a system over from scratch, definitely buy one.

Incidentally, I have read in many places that used R-12 hoses work just fine with the smaller molecules of R-134a. The mineral oil under pressure filled the microscopic pores so leakage rates are only a little bit higher than if you bought new barrier hoses.

Straight propane doesn't have quite the right temp/pressure curve (that's another reason they add butane to bring it down a bit). I've also heard that propane doesn't carry the oil as well as the butane component of the mix.

MACS and Dupont lobbied the Great Balls of Fire Scenario (TM) successfully to have HC refrigerant banned in 19 states (and by the EPA for mobile use, although not for some stationary refrigerant use!) BTW what does seem to work well is R-152 aka "Dust-Off" cans. Haven't tried it yet but it's getting cheaper than R-134a...

 

[chris142]

I specialize in auto AC. Unfortunately I'm not close by. But...have any existing R12 removed. RelaceR all seals at every connection,flush out the mineral oil,replace Schrader's,install an orange orifice tube,add 10oz of Ester oil,replace the accumulator,vacuum and charge to 85% of the r12 amount with r134a

 

[BrianX128]

I swear by https://www.amazon.com/Case-12-cans...95&sr=1-2&keywords=redtek+12a#customerReviews

This redtek 12a stuff. You can tell by the reviews it seems to work for everyone in various old vehicles. That's a giant pack of the cans but still. It's revived all of my old ac systems, just empty system entirely and put in some ester oil first to swell and fill the seals as you fill it with this stuff so you don't waste any initially. Mixes with the mineral oil that was leftover from the R12, and it's cold and doesn't leak out. Never had an issue with it and these were in two trucks of mine that would lose cans of 134a almost as fast as you filled them up.

 

[MTKirk]

My theory is that the first time your MB was overcharged and the high pressure blew the o-ring. HC's only have a few oz. between under- and over-charged. I always start low, go slow and watch the gauges patiently

I doubt it, I always charge by weight, particularly with envirosafe as high side pressures are lower than original R-12 specs.

 

[MTKirk]

I swear by https://www.amazon.com/Case-12-cans...95&sr=1-2&keywords=redtek+12a#customerReviews

This redtek 12a stuff. You can tell by the reviews it seems to work for everyone in various old vehicles. That's a giant pack of the cans but still. It's revived all of my old ac systems, just empty system entirely and put in some ester oil first to swell and fill the seals as you fill it with this stuff so you don't waste any initially. Mixes with the mineral oil that was leftover from the R12, and it's cold and doesn't leak out. Never had an issue with it and these were in two trucks of mine that would lose cans of 134a almost as fast as you filled them up.

Yep, pretty much the same stuff as envirosafe. Nothing works better in an R-12 system, not even original R-12.

 

[david85]

Brian, that's the stuff I used. The first HC-12 I tried was "Duracool" but that seems to be no longer available. I have no problems with Redtek though. Even in canada, the price isn't bad.

As for getting the new cross flow condenser, it was mainly to protect the new compressor, which no matter what is always the most expensive part in the AC system.

 

[DrCharles]

I specialize in auto AC. Unfortunately I'm not close by. But...have any existing R12 removed. RelaceR all seals at every connection,flush out the mineral oil,replace Schrader's,install an orange orifice tube,add 10oz of Ester oil,replace the accumulator,vacuum and charge to 85% of the r12 amount with r134a

Are you positive about those numbers? The stock orifice tube is blue (0.067") and for R-134a a red (0.062) is usually installed. The orange tube is only 0.059, will that keep the evaporator flooded?

Also, the spec I found for our trucks (at least my '93) says the original oil capacity was 7 oz. My compressor came with 3 oz. precharged, so I added four oz. Adding ten ounces sounds like a lot of oil...

 

[chris142]

Yes the orange tube will give you cooler ac. Has to do with the evap and boiling of r134a. All cars that use r134a from the factory use a smaller tube than the r12 cars did.

 

[DrCharles]

As I said in my reply already, the red (0.062) is smaller than the blue (0.067), and of course it "has to do with" the different mass flow using a different refrigerant. You're the only one I've ever seen that recommends an even smaller orifice than .062.

As the orifice gets smaller, idle cooling will improve, but at the expense of highway cooling. And a smaller orifice also means less refrigerant can flow through the evaporator, which will eventually be noticed in a reduced ability to transfer heat out of the cabin... Maybe in south Calif. it's not as hot and humid as some other places?

 

[79jasper]

Actually the orange is common around the Ford forums.
Can't say that it's right or wrong, but many seem to get good use of it.

Sent from my SM-G892A using Tapatalk

 

[chris142]

As I said in my reply already, the red (0.062) is smaller than the blue (0.067), and of course it "has to do with" the different mass flow using a different refrigerant. You're the only one I've ever seen that recommends an even smaller orifice than .062.

As the orifice gets smaller, idle cooling will improve, but at the expense of highway cooling. And a smaller orifice also means less refrigerant can flow through the evaporator, which will eventually be noticed in a reduced ability to transfer heat out of the cabin... Maybe in south Calif. it's not as hot and humid as some other places?

I am in the south end of death valley. Summer is often over 100f with 106-107 common here. Go north into death valley and 115-120 is normal.th orange tube works here.

 

[towcat]

I am in the south end of death valley. Summer is often over 100f with 106-107 common here. Go north into death valley and 115-120 is normal.th orange tube works here.

years ago I was heading out to TX for travel/work. stopped in Victorville to visit another member. headed out about noon. It was really getting warm. Sitting in traffic waiting to get on the freeway, my freshly converted R134 system vented. needless to say, it was a very warm two months.

 

[DrCharles]

That does sound unpleasant. And also why a high-pressure cutoff switch is required for R-134a conversions! Especially if they don't have a good condenser, a pusher fan or both...

 

[raydav]

I would like to second the motion on Envirosafe. I have several vehicles that started as R12 systems. I have serviced them with Envirosafe without making any changes to the system - no "conversion". I vacuum for about a minute, and charge till the low side is thirty pounds.

When I replaced the IDI in my van I replaced the compressor with a 508. I have seen vent temps of 39f.