Eh ?



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Basically moisture from compressed air will destroy a central air system in short order. I personally have never seen one leave a crater, I shire would like to see it.

Mobile systems are more tolerant to moisture, but sweeping the system with nitrogen helps blow out any moisture that was boiled out during vacuum. You really wouldn't think its there, but with a vacuum gauge you can really tell.

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Eugene

10 E63 AMG
93 300te 4matic
07 BMW X3
14 Ford F-150 Fx2

Sorry I didn't finish explaining .
I was only referring to what a bad mix AIR is with A/C systems .
An example is AIR/Compressed air being used for a leak check (PREASURISING A SYSTEM) OR flushing a line if that air meets and mixes with the compressor oil . Boom can occur. Always nitrogen, clean safe, inert . added benefit it helps absorb MOISTURE in the system. If a system has been open for a prolonged time or LOW on refrigerant it can run in a Vacuum where AIR can enter , If air enters so does moisture. Only 2 good ways to remove moisture .1 use nitrogen and allow it to stay long enough in the system to absorb, then purge it off. DO NOT run the system with nitrogen inside. 2 A good vacuum . IT Can only be measured with a vac u stat. A good Vacuum is 1000 microns and lower. the ideal vacuum is 500 microns and lower. This unfortunately can not be measured by gauges.
Also remember with car A/C systems that were not designed for 134A from manufacture The condenser just cant do the job properly . Meaning the condenser needs to be a lot larger or the refrigerant charge lower. A poor compromise . TX valves should always be changed if a system changes refrigerant . More flow is required with a LESS yielding refrigerant . High head pressures are MOISTURE in the system, secondly Restrictions. Or a inefficient condenser, Remember also oil migrates around the system with the refrigerant. DO NOT blow it to places in the system where it cant return unaided. Thank you for the link. a good read I am new to forums and still finding my way. No disrespect meant for anyone.

Are you suggesting that the compressor can auto ignite the oil in an a/c system ? or the gas, should you be using propane?

I think you ought to read this :Fuels and Chemicals - Auto Ignition Temperatures

These temperatures listed only exist inside a diesel engine and to start most diesels it is often only with the aid of glow plugs...ie: An ignition point.

I doubt any refrigerant pump can run at these temps'....and where would the ignition point be ?

The 'hole in the ground' sounds spurious.
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"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

I think he may be referring to the danger of oxygen + oil in an oxy-acetylene regulator/tanks setup, where pressures can be in thousands of psi. But we are talking air at 200 psi.

"By volume, dry air contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapor, on average around 1% at sea level, and 0.4% over the entire atmosphere."

I was wondering if air can be used to do a poor man's "nitrogen" pressure test in a mobil AC system since it is 78% nitrogen. Is there a danger of an explosion with 21% oxygen and refrigerent oil pressurized to 200 psi? Gut feeling WAG tells me no.

Granted, some moisture (relative humidity dependent) will be introduced from ambient air, but since the dryer and TXV will be replaced and the system evacuated afterwards, whatever moisture introduced will be removed.

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83 300 D turbo 297K runs great. SOLD!
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I vacuum the system for 5 hours or so on vehicles that have been open for some time. Blowing out the system with shop air is okay as long as you purge with refrigerant before charging.

The ox-acetylene sets potential to explode is well known, either due to fire or incompetent handling.https://youtu.be/iam27Mh1zu4



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__________________
[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

Holy smoke, that's some fireworks!

What do you use for a vac pump, single or dual stage? What vacuum level do you get it down to? What do you use for a vacuum gauge to see the level achieved?

__________________
85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Single stage commercial . Have calibrated gauge and at 1100 asl I see 29 inches. If you hold 29 for some time and run the engine to full temperature you can be sure that whatever minute amount of water vapor is in the system is absorbed by the desiccant....or so small a volume it will not ice anywhere..


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__________________
[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."