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This refrigerant + compressor oil inspection sight glass & micron gauge is worth it !
Guys,
I was doing my friend's 2007 Toyota HVAC for gaining experience, model is Asian type called Fortuner. Its like a little brother of Land Cruiser.
He sometime ago got a workshop to replace his condenser, not because of a leak but it was corroded and he replaced it as preventive.
So, I got the chance to work on an HVAC system already worked on by non factory personel.
My my, my friend's HVAC system was crazy wet, heavy moisture content.
See milky color for liquid r134a + water moisture + oil
r134a totally disposed and vacuum down for 15 hours !!!!
Stubborn water vapor. Nitrogen purging a few times required.
Started 6:21PM on 25th April, by 1 hour later by 7:29PM I can bring down to 639 micron and with moisture "explosions" as shown on the hill and valley of the logger graph.
Those are water vapor un-sticking itself from hoses, metals and oil .......... as evacuated by the vacuum pump.
The hill peak is the water vapor un-sticking.
639 microns is equal to :
By midnight 26th April 12:25AM or 6 hours of vacuuming and after 2 times nitrogen purging to "shake-off" water vapor from internal of HVAC system, I am still getting the "explosions" but at less frequency.
I went to bed and let the vacuum pump keep running. Next day 26th April, 7:12AM or after 12.5 hours of vacuuming, the water vapor explosions getting lower and lower frequency, but still there.
Done 1 more time ( 3rd time ) long nitrogen purge and the allow pump to rest 45-60 minutes.
Vacuum again at 9:00AM and by 9:36 AM water moisture is gone.
By 10:00 AM vacuum decay test conducted and it pass 30 minutes later.
End of evacuation/vacuuming by 10:30AM. Total 16 -1 = 15 hours. Insane !!
Recharge R134A to 810 grams ( double EVAP ).
Test HVAC...so cold, awesome. This is old fashion fixed displacement compressor, only ON-OFF capable, no 50% throttling down like our variable displacement compressor.
Test the refrigerant color clarity again and all super clear, with a bit of super light amber of the oil. This is a 2007 car.
Without these 2 tools ( and a decent vacuum pump + bigger 3/8" hose ) , I can never detect such water vapor contamination and dry the system properly.
Forget analog capillary vacuum gauge, it can't read moisture , it will shoot down to maximum 29.9 inch Hg visually within 30 minutes of vacuum pump operation and you think all good.
Like a scope, we can't troubleshoot CAN BUS signal without it.
Compared to the overall damage few years later, from a wet system will do to compressor's black death and throw away EVAP + Condenser, as these micro channels type CAN NOT be flushed/cleaned = US$ 5K or more in USA ?
I think it will be cheaper to inspect early and do preventive, as our car is aging already.
.
Hope this helps..........
Last edited by S-Prihadi; Apr 27, 2023 at 06:07 AM.
Thank you Master Surya for showing us inside the liquid side of A/C lines -
These two Amazon tools you have selected work a treat with your vacuum pump, super hose upgrade and skills.
200psi liquide side AC window (! up to 5000psi)
I wonder how to use that window conduite with two ports from where to where on the condensed liquid side ??
How to see the milk mix... before vacuuming?
How to inspect after refill is done with scale and without introducing air in line and R134 total load.
I understand there is a sort of AC specialist protocol to work with dry-vacuumed systems and refills. Would you say inert gas is almost mendatory to help dry insides.
> NOW MY CANDID QUESTION.... :
Can you run a A/C circuit on a CO2 load alone for testing purposes only. May not cool good but at least run system.
Is it going to condense & expend and exercise TXV, control valve etc...
me too nearly A/C newbie
Last edited by CaliBenzDriver; Apr 27, 2023 at 07:15 PM.
The Sight Glass is a 500 psi rated maximum. I would not use this on other than R22, R134A and R1234yf. If R410 the working pressure is higher.
Its inner tube item 1 is the real pressure "pipe", the outer tube item 2 is only to prevent condensation by trapping air between itself and inner tube , using air as thermal insulator like Thermos vacuum flask using ZERO-AIR as insulator.
Cali asked : I wonder how to use that window conduite with two ports from where to where on the condensed liquid side ??
However, don't vacuum the Sight Glass less than 20 minutes, because we want under 250 microns if possible.
I have modified my sight glass a bit, for better vacuum result. I removed its vacuum port where it was originally using LP quick R134A coupler, instead I use its 1/4' 45 degrees flare , bigger orifice opening.
I also do not use the MasterCool original R134A LP and HP coupler, because it is a Normally Open type, no valve on it. I use my own R134A coupler, which has a spin type valve on it.
The small ones are the MasterCool normally-open valve/coupler.
Albeit I have added extra ON-OFF valves on my test rig, I hate using r134A coupler of Nomally-Open type, not good.....less control.
================
Cali asked : How to see the milk mix... before vacuuming?
Actually if one does not have a vacuum pump, one can still use this Inspection Sight glass, with wasting a bit of R134A in gas form, not liquid form.
If engine is OFF and static pressure on HP side has reached its metal/condenser temperature or 30 minutes after engine + HVAC shut off, the R134A will be in a liquid+gas state or known as its Saturated Temperature/Pressure.
Let say at 30C or 86F, the gauge pressure of R134A would be 104.1 PSI measure at the HP port.
Red handwriting is PSI
See the sharkfin shaped zone below written as LIQUID - VAPOR MIXTURE ... that is R134A as-is when not doing any work in an HVAC system.
R134A will always be LIQUID + GAS when static.
Left of sharkfin zone is condenser making R134A 100% liquid state ( Subcooled ) . Right of sharkfin zone is 100% vapor state , that is the evaporator zone ( superheat ).
The middle of the sharkfin has 0.1 and up to 0.9 in blue, that is 0.1 or 10% or 0.9 as 90% of gas state proportion of the R134A , and depending on how much heat/energy it is absorbing or releasing ( enthalpy ).
Our W212 HP port is higher than the condenser and compressor by vertical position. With engine OFF, HP port will discharge gas form of r134A one can use as purging gas to make hose being removed
of atmospheric air aka a dry system. Purging is so much faster and easier than vacuuming for removal of ambient air.
To see the MILKY thingy, which it is LIQUID state of R134A + compressor oil + whatever contamination and including water vapor, the HVAC has to be running.
When HVAC is running, the compressor compressed the R134A while at 100% gas state, and condenser then condensed it to 100% LIQUID STATE and liquid R134A is what we can capture at the Sight Glass.
Since compressor oil is part of the circulation of R134A when HVAC is running and also any water vapor, the capture R134A at the sight glass when HVAC is running, shows everything we need to see.
Actually gauge manifold has a small sight glass too, but it is too small and one sided is not open to light, seeing the R134A for inspection purpose is not as good as the fat big MasterCool sight glass.
To see compressor oil well, without liquid R134A, we need the MasterCool Inspection Sight Glass as visually it is easy and we can collect the trapped oil too.
What one need to visualize in their mind, is how and when and which valves to open/close and must practice in real time how much valve opening equals to what level of flow.
When we return the R134A liquid state in the Sight Glass to the car HVAC system, we need to return it as vapor form to LP port while engine is running, so that the compressor wont get liquid hammer damage.
This, one must practice in real time. I use my wireless pressure gauge when operating the Sight Glass, as I can't see R134A when in gas form, but I can measure its pressure....me still newbie you see.
Per 1 time you do refrigerant inspection using the sight glass, you will loose approx 1 to 2 cc of compressor oil as it will soak the HP side hose and internal of the Sight Glass.
When done right, the R134A loss is only so little, as long as you loose R134A in vapor form and not liquid form.
This is why I do not like using MasterCool original normally-open type of R134A coupler and instead use the Yellow Jacket R134A coupler with spin type valve, because I am still a newbie. I need more flow control mechanism.
====================
Cali asked : How to inspect after refill is done with scale and without introducing air in line and R134 total load.
I understand there is a sort of AC specialist protocol to work with dry-vacuumed systems and refills. Would you say inert gas is almost mendatory to help dry insides.
Having nitrogen is a great help, yes and I say it is a must, because we are working on an aging HVAC system.
To do proper vacuum and proper re-charging the R134A to our HVAC system, no choice but to invest $$$ suitable machine/devices/tools.
That is why I started this post : https://mbworld.org/forums/e-class-w...ware-wise.html
If you spend time and really a lot of learning time, on these 7 youtube channels/video below, you will freak out on how bad the general understanding and practice of car HVAC system how-to compared to a proper professional commercial level guys,
because we are dealing with invisible stuff and most people do not want to spend time learning. Water vapor is not something our eyes can see, unless massive steam form....but water vapor and other non condensable gas is our enemy.
Non-condensable gas is from poor workmanship, and/or fake R134A or bad quality R134A....those jerk-off cans as Tom Lech likes to call those small bottles.
The Snap-ON 3R machine and Texa 3R machine user manual and technical manual, helped me understand how the 3R machine works and how a dumb-azz operator can ruin everything too.
I am attaching if you want to read them.
Channels and videos one can use for learning.
01. Tom Lechhttps://www.youtube.com/@coldfinger459sub0
His video is all over the place, recorded live in real time no edit nothing, but most are "gold" when we already started to understand the HVAC 101.
He will reply to 99% of your question, he likes when people do proper HVAC work.
He is my Mentor, I asked him a great deal.
02. This 1 video you need to keep watching again and again, it explains R134A behaviour in a simple to understand manner. Ron Walker. Refrigerant cycle. Only watch this 1 video.
08. Attached Lab grade vacuum basic PDF which our car HVAC vacuum level is like kinder garden grade and the Lab guys are Phd.
===================
Cali asked : > NOW MY CANDID QUESTION.... :
Can you run a A/C circuit on a CO2 load alone for testing purposes only. May not cool good but at least run system.
Is it going to condense & expend and exercise TXV, control valve etc...
CO2 is also a refrigerant for HVAC, it is called R744. Propane too can be used as refrigerant, it is called R290.
The working pressure of C02 is very high and at one time Mercedes tried using this instead of r1234YF. However MB abandoned R744 eventually. The CTI video has the MB C02 refrigerant full story.
I spent a few hundred hours learning these HVAC thingy by videos and by publication.
I am no more blind or HVAC stupid , I understand much better today and I am still learning more.
The most difficult portion for me to wrap my head around is the enthalpy.
It is difficult to want to know the precise mix ratio at a point in time at various section of the HVAC system , between liquid and gas form of R134A proportion.
Vacuuming is much easier to understand, but we need to experiment a lot using various hoses and must have a micron gauge.
My experience with super dry air for my dive compressor using the insanely expensive -80C dew point sensor helps a great deal on understanding "drying" using vacuum.
Reading is 1 thing, having the instrument and seeing them work in real time is the only way to learn properly.
.
Last edited by S-Prihadi; Apr 28, 2023 at 09:11 AM.
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