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A/C hose (Red-Tek) burst (Update and new issues)
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RufusRockwell
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PostPosted: Sat Jul 24, 2021 5:46 pm    Post subject: Re: A/C hose (Red-Tek) burst (Update and new issues) Reply with quote

Well, I'm so closer to getting my A/C squared away but may have a setback.
I received the additional Red Tek and oil but the system just does not seem to want to suck it in...i.e. when I hook up a can it doesn't seem to be emptying. The pressure is at around 20- 30psi depending on the rpm and it's blowing cold-ish but not as cold as it did/should. It's only got one can in it so it seems that it should be able to take at least one more. I think that I used 2.5 cans last time.
The compressor is still emitting a Brrzzzzzzzzz-Zzzzzzzzz sound which it did not do before so I'm wondering if this whole ordeal didn't mess up the compressor. I'm feeling like I should get a new compressor, and re-charge but I'm just speculating at this point.
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Howesight
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PostPosted: Sat Jul 24, 2021 7:16 pm    Post subject: Re: A/C hose (Red-Tek) burst (Update and new issues) Reply with quote

I am assuming that you are filling the RedTek on the low pressure side of the system and with the engine running and compressor engaged.

If so, here's what you need to do:

1. Have a helper raise the engine speed to 2,000 to 2,500 rpm;

2. Apply heat to the can of RedTek using a blow drier on high or a heat gun on low or medium. Befoe starting this process, be certain that you have properly opened the RedTek can with the piercing needle and then backed the needle out to allow for the RedTek to flow into the connecting hose.

3. Have patience - - it takes time to boil the RedTek refrigerant in the can. The actual time depends on the amount of heat you are getting into the can. At a certain point, when all the RedTek has evaporated and exited the can, the can itself will get noticeably hot. This is because the liquid-to-gas phase change is not longer occurring as all the RedTek has turned to vapour. At this point, switch to the next can.

4. The odd sound from your compressor is occurring because there is not enough refrigerant in the system. It will quiet down as you get the refrigerant into it.
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djkeev
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PostPosted: Sun Jul 25, 2021 5:05 am    Post subject: Re: A/C hose (Red-Tek) burst (Update and new issues) Reply with quote

What do your gauges tell you?

Too much refrigerant will create all sorts of new problems for you including compressor failure!

Dave
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RufusRockwell
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PostPosted: Sun Jul 25, 2021 8:56 am    Post subject: Re: A/C hose (Red-Tek) burst (Update and new issues) Reply with quote

I'm just using one gauge for the low side. I had to return the full gauge set to Autozone. The low side is reading around 25-30 depending on the rpm. I really don't think it could be overfilled though as I've only put in one can so far. When I tried filling yesterday I was not displaying the patience recommended by Howesite since in the past, the cans emptied pretty quickly and this time It seemed that nothing was happening. I figured something was wrong and was worried the system was gonna blow up if I kept at it (dramatic I know but I don't have a lot of experience with this kind of thing!) I'm going to try again today as per Howesite's recommendations and see how it goes.
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djkeev
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PostPosted: Sun Jul 25, 2021 8:59 am    Post subject: Re: A/C hose (Red-Tek) burst (Update and new issues) Reply with quote

When I recently charged mine it took so long that engine heat and exhaust killed the grass where I was parked.

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RufusRockwell
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PostPosted: Sun Jul 25, 2021 9:03 am    Post subject: Re: A/C hose (Red-Tek) burst (Update and new issues) Reply with quote

Whoa! So, how much time is reasonable?
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PostPosted: Sun Jul 25, 2021 9:06 am    Post subject: Re: A/C hose (Red-Tek) burst (Update and new issues) Reply with quote

RufusRockwell wrote:
Whoa! So, how much time is reasonable?


Yep.

Keep the can warm in your hands.
I was taught back in the Early 70’s with r12 to swirl it and occasionally tip it so it gets a small gulp of liquid.
Never let the low side ever gulp liquid and go above 40 psi.
Liquid can lock up a compressor.
With gauges there is a window to view liquid or gas.

Redtek actually says to put it in inverted, but I would NEVER do that on a running compressor!

Dave
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RufusRockwell
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PostPosted: Sun Jul 25, 2021 9:08 am    Post subject: Re: A/C hose (Red-Tek) burst (Update and new issues) Reply with quote

Alright. I'll report back later today.
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PostPosted: Sun Jul 25, 2021 10:21 am    Post subject: Re: A/C hose (Red-Tek) burst (Update and new issues) Reply with quote

Is it normal for the can to get very cold when filling? I don't recall this happening before.
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Howesight
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PostPosted: Sun Jul 25, 2021 11:34 am    Post subject: Re: A/C hose (Red-Tek) burst (Update and new issues) Reply with quote

Hi Rufus:

[Note to those reading the post below: These comments below are tailored to Rufus who does not have an AC gauge set and is relying on the RedTek cheapo gauge that only gives low-side pressure.]

Yes, it's normal for the can to get cold when installing refrigerant. The phase change from a liquid to vapour is the magic that makes refrigeration work.

The phase change can occur from either (or both) a reduction in pressure or from adding heat to the liquid refrigerant. When your compressor is operating, it lowers the pressure on the low pressure side of the system to around 26 to 32 psi, depending. When the compressor is operating, the pressure on the high side, again, dependent on conditions, will be anywhere from 120 psi to 220 psi.

You can't get much of an idea of the refrigerant fill level from the pressure in the system. Pressure is, at best, only the most vague indication of fill level. For example, at a given ambient temperature, with the compressor off, the system pressure will be the same on low and high sides and will vary directly with ambient temperature. But once you operate the compressor, if the refrigerant fill is low, then the pressure on the low side will be low (say, 20 psi approx., or even lower) and the pressure on the high side will also be rather low, say, around 100 psi. (Don't use my pressure illustrations to diagnose or measure, please - - these are just illustrations).

There are really only three ways to get a proper measure of refrigerant fill:

1. After applying the R12 to Red-Tek conversion ratio (because RedTek and R-12 behave differently), install the factory-specified weight of RedTek;

2. Use a known quantity established by those who have done this to Vanagons before you: In the case of RedTek, we know three cans works nicely, provided you don't have too much leakage when connecting the cans;

3. Fill bit-by-bit while measuring vent temperatures until the lowest temp is achieved.

Regardless whether you use 1 or 2 above, you can still adjust the fill (adding or venting refrigerant) to achieve the lowest vent temps. But this is a difficult thing to achieve in the Vanagon, my experimentation has shown. The reason for this is that on the Vanagon, it is very hard to replicate the conditions you will have on the highway. If you have a super-powerful box fan or fans, you might get close to replicating highway conditions. On other vehicles, I find the rad fan (or fans) do an adequate job.

So, imagine, in your mind's eye, the first time I highway-tested my Vanagon DIY AC system: I literally had my gauge set duct-taped in place with the gauges outside and plastered onto the windshield, facing in, while I glanced at the temps on my vent temp thermometer, all while driving 65 MPH. Quite a sight! (My service ports are on the front of the Van). That is how I found the "sweet spot" for my system. This is not necessary unless you are a perfectionist/geek, so worry not.

A quick comment on the first can of RedTek: If you are following the procedure I set out in a long post long ago, then you are installing the RedTek into a system vacuumed down to 29 inches of vacuum WITHOUT THE COMPRESSOR RUNNING. The vacuum allows you to install the first can as a liquid, (with the can upside-down) which is fast. After the first can, you need to use the compressor to reduce pressure on the low side to boil the refrigerant in the can and suck RedTek vapour into the low-side fill port. I turbocharge this process by adding heat to the RedTek can with my heat gun. Be patient and think of how long it takes to boil a pot of water dry - - that is what you are doing with the liquid RedTek.

I know that the RedTek cans will not burst in this process. My Audi S6 has no low-side service (ie "fill") port, so the refrigerant all goes in through the high side port with the compressor NOT running. The dealership has a very expensive machine that weighs the refrigerant and pumps the correct mass into the high-side fill port. I DIY this using my heat gun, installing all the RedTek with my gauge set and heat gun through the high side service port.
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RufusRockwell
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PostPosted: Sun Jul 25, 2021 12:42 pm    Post subject: Re: A/C hose (Red-Tek) burst (Update and new issues) Reply with quote

Howesite, thanks for the detailed response. I was able to get 1 more can of red tek in by following your previous suggestions. I used a blow drier to heat the can for about 5 minutes and then just went slowly until the system took it in. The can got cold quickly. I would disconnect intermittently to check the pressure and to see how much was left inside the can. Pressure is around 30 at idle and drops a bit as rpms increase. The compressor buzzing seems to have gone away and the A/C is blowing about as cold as it did before. I'll take a vent temp reading later today. Your pressure test on the highway must have turned some heads! Good thing you didn't get pulled over!
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