Anyone service their own a/c?
- Thread starter adam2562
- Start date
adam2562
New member
lane:I worked 27 yrs on 20 ton transportation HVAC systems. did all the testing repairs except overhauling the compressors.
when the unit required soldering in parts nitrogen was used . then pressurize the system with nitrogen and see if it holds pressure if not then leak check .. that good then put the new oil in and vacuum the system down . 3-4 hours then see if it holds . then shoot in a few lbs of R22 and using the leak detector see if its good then finish it off .
leak testing was done on the inspections . pressure testing was done with a heat load to determine the compressors ability to create the proper pressures and adjusting the unload-er valves for proper operation.
used a scale for charging , but the end game was getting the correct pressures with the heat load . I could apply full heat on as I checked for full cool operation . refrigerant weights would vary slightly never exact . R22 . also a level glass on the unit to determine the charge.
many just use the low side on these auto vehicles . obviously I do use the gauge set HI/LO when checking for proper operation on my vehicles and use the OEM pressure chart ,never had a problem .
old vehicle ac compressors do take a lot of abuse with the seals leaking then the compressor requires replacing . many use the wrong refrigerant oil and also never use a vacuum pump or even flush out the system. I have seen auto mechanics do it that way ... also using refrigerant to sweep out the system.. EPA loves that .. being as old as I am we used to use R13 to clean parts on the vehicle ... no wonder the ozone got damaged .. hair spray/paint also used ozone depleting gas as well.
R134 is very safe compared to the freon R12/22 materials soon R22 will be gone ..
working on the motor vehicle refrigerant all you need is goggles and gloves.
with small cans sold to non licensed people not a big worry .. with a 125 lb tank now that is a lot different aye..
what he should do is learn about servicing an auto ac system first . then with a gauge set , see what the pressures are. then if its available get the Toyota ac service chart to see how the temperature pressure relationships match . too much or too little charge .. or compressor not pumping properly [bad valves/restrictions]
I have to get that toyota ac chart ... may need it soon.
when working with ac systems some refrigerant will leak out R134 no big deal .. R12/22 is bad to breath in bad for your health but not an issue now on motor vehicles with 134 .
when the unit required soldering in parts nitrogen was used . then pressurize the system with nitrogen and see if it holds pressure if not then leak check .. that good then put the new oil in and vacuum the system down . 3-4 hours then see if it holds . then shoot in a few lbs of R22 and using the leak detector see if its good then finish it off .
leak testing was done on the inspections . pressure testing was done with a heat load to determine the compressors ability to create the proper pressures and adjusting the unload-er valves for proper operation.
used a scale for charging , but the end game was getting the correct pressures with the heat load . I could apply full heat on as I checked for full cool operation . refrigerant weights would vary slightly never exact . R22 . also a level glass on the unit to determine the charge.
many just use the low side on these auto vehicles . obviously I do use the gauge set HI/LO when checking for proper operation on my vehicles and use the OEM pressure chart ,never had a problem .
old vehicle ac compressors do take a lot of abuse with the seals leaking then the compressor requires replacing . many use the wrong refrigerant oil and also never use a vacuum pump or even flush out the system. I have seen auto mechanics do it that way ... also using refrigerant to sweep out the system.. EPA loves that .. being as old as I am we used to use R13 to clean parts on the vehicle ... no wonder the ozone got damaged .. hair spray/paint also used ozone depleting gas as well.
R134 is very safe compared to the freon R12/22 materials soon R22 will be gone ..
working on the motor vehicle refrigerant all you need is goggles and gloves.
with small cans sold to non licensed people not a big worry .. with a 125 lb tank now that is a lot different aye..
what he should do is learn about servicing an auto ac system first . then with a gauge set , see what the pressures are. then if its available get the Toyota ac service chart to see how the temperature pressure relationships match . too much or too little charge .. or compressor not pumping properly [bad valves/restrictions]
I have to get that toyota ac chart ... may need it soon.
when working with ac systems some refrigerant will leak out R134 no big deal .. R12/22 is bad to breath in bad for your health but not an issue now on motor vehicles with 134 .
Last edited:
rigtec
New member
Hi catrains,
Our forum community is made up of all types of folk, but for the most part this is a t/s (Technical Support) forum! We have quite a few experts here, many who specialize in different areas of repair. So if I start a thread and post a question, and let's say I get a few replies but still no one could give me the answer that I need, there's usually someone out there who knows who to contact (@bobbya/c), who can answer the questions that will help me to get it back online. I've seen a lot of excellent support exchanged on the t4r.org tech boards, but I've not seen (up til now) any of the older, more experienced community members answer a plea for tech help by diverting the original questions and referring to the EPA's 'Clean air act' of 1996, discussing all the different types of ozone depleting refrigerants...
There are some refrigeration machines that are commonly referred to as Critical charge systems "Such as": small water coolers, some ice machines, even domestic refrigerators... because those systems are so small that there's literally no room for error regarding it's refrigerant charge, so they need to have their system charge weighed in. So units like that are considered "critically charged"!
A critically charged refrigerating device is called that because it has nowhere to store any extra freon should the heat load swing upwards or downwards; it's designed to maintain a very close temperature control range. And it's metering device e.g., capillary tube, or a piston measuring orifice has a relatively "Fixed" flow range... another words it can't open up more to allow more refrigerant to flow, neither has it the ability to close (throttle) down to restrict to refrigerant flow when the heat load is lower.
The 4Runner otoh "IS NOT" a critical charge refrigeration system, nor does it use a "Fixed" metering device like the ones described above. It uses an "Automatic thermostatic expansion valve" to control refrigerant flow and has an abundance or cooling range, due to the wide variety of temperatures that the vehicle will be subject to! Also, it's expansion valve has a non-adjustable (Fixed) superheat setting to help protect the compressor from liquid slugging that can be caused by sudden temperature swings that come with the territory of automobile air conditioning. As far as a seasoned HVAC/R technician needing a "Toyota published" P/T (Pressure/Temperature) chart and a full manifold set to charge the A/C system with 134A...
I find this statement to be a highly subjective one. Chances are: If you would tend to depend on a P/T chart and a full manifold gauge set (one with a high and low pressure gauge) when charging a residential condensing unit or a commercial rooftop unit, then chances are, you would likely need to be assisted with these help tools when trying to charge up an automobile's air conditioning system! But... if you are a well experienced hvac tech and understand that there are many ways to know exactly how well an air conditioning system is performing, whether it happens to be an suv, or 5 ton residential system, or a 100 ton self-contained rooftop unit and don't need to rely on a p/t chart or a high-side pressure gauge, then you'll do just as well when adjusting the charge on your 4Runner's a/c system!
cheers
