I am replacing the expansion valve for the dash a/c. I will be replacing the dryer. I am also flushing the evaporator, condenser and the lines. I will be installing new O rings. I have sticker on the coolant tank that says it takes 5 pounds of r134a. I know I have to add Pag oil back into the system. My question I have not been able to figure out is which Pag oil? Also how much do I need to add? I saw this article during my forum search. https://www.foreforums.com/index.php?action=dlattach;sa=tmpattach;attach=post_tmp_8100_9791f8be7c660346a5ef37c7b4cf49f3;topic=0 It says to add 1 ounce per 10' of coach length on my coach that would be 3.6 ounces. I plan on leaving the oil that is remaining in the compressor in there. Any guidance is appreciated. Thanks!
Pag oil - Google Search (https://www.google.com/search?q=Pag+oil&sourceid=chrome&ie=UTF-8)
Yes I did google it. There are different viscosities of Pag oil with different numbers associated with them. I thought my question of which Pag oil was fairly clear. Thank you for your input.
I install a new Sanden a few years back. It had Sanden SP15 from the factory. Drained and measured compressor oil, refilled so I knew what it had. The system was flushed, dyer replaced. Total I used was 8oz. I believe the older Sandens had SP20. I think SP15 is PAG100. Your compressor may have a decal to verify this. It's better to have a little to much oil in the system than not enough as it circulates around. If you don't have a Sanden compressor you'll have to check with that brand. I would recommend Sanden OEM oil because some of the PAG coming out of China is not very good.
My 2 cents.
Ok thanks. So the compressor I have on there will determine the type of Pag oil it uses? That makes some since. I will check the compressor.
MOST new Auto AC compressors have a label that states what type of oil it uses, and itself usually full with the proper charge. But that is for auto application, a RV would be a bit different. I always drain and measure whatever is in any new one I buy, Mark that down as reference for whatever the total would be. You also when flushing a system, and installing new Dryer, hoses, compressor need to spread that oil around. Pour some in compressor, some in the new dryer, hoses, etc...PAG OIL is the preferred for a 134a System, most but not all using Pag100.
here is a good link that I have used for years as ref.
A/C Compressor PAG Oil Application Chart (https://www.aa1car.com/library/pagoil.htm)
The compressor that is on my coach now is an International Components Engineering SAE-J639. There is no tag or label telling me what oil it takes or what quantity. The compressor my build sheet says came on the coach new says it was a Seltec 16HD. I read on the internet that the Seltec 16HD takes Pag oil 46 not sure how many ounces it came with. I have 2 different thoughts on how to approach this 1) Replace working compressor with a Seltec 16HD confirm which oil it comes with. Then add an unknown (at this time) amount of oil to my flushed evaporator, condenser and lines. So I know I have the correct oil for the compressor. Or 2) Take off my current compressor (SAE-J639) drain the oil from it. Do more research to try and figure out which Pag oil it takes. Put the proper amount of oil back in the system. Does any one know what the right amount of oil would be for the whole system, if I removed all oil? I hate asking this many questions I just don't want to screw this up. Thanks
This might help.
https://www.extant.gr/datafiles//ICE%20COMPRESSOR%20COMPLETE%20SERVICE%20MANUAL.PDF
So why are you replacing the expansion valve? Im assuming hi differential pressure across it? The receiver dryer is just before it. Last couple of coaches I worked on had bad corrosion in the dryer contaminating the expansion valve. Remove it first and cut it open to visually inspect. If it's corrosion free great. If its full l of corrosion as mine have been the pressure line should be replaced, but ive cleaned as best I can and have planned to replace the expansion valve again in a year or so. Dryer too. Having a AC machine makes this practical. Also Ive started changing the condenser coil and convert to the flat tube from the round tube. Everything removed will require additional oil. Several benefits to the flat tube condensers. Less Freon , larger cooling capacity for the same size, more restrictive capturing failed compressor components. Regardless it all costs a lot more to repair.
Your Seltec is near identical to a Denso which also used P46....YOu compressor is still sold at,
Genuine Seltec TM-16HD Compressor - Auto Air Online (https://www.autoaironline.com/ac-parts/seltec-tm-16hd-compressor-315)
The link I gave you gives a baseline that works for just about any system on the fluid levels. Both the evaporator and condensor in my U295 is about the same as most in a full size truck, so those values are about the same, assume your coach to be about the same size.....the only dif is that you have lots more line. Id probably add about and extra 1.5 -2 oz for the additional line length.
Use the following guidelines for replacing compressor oil when changing A/C components:
Compressor.........1.4 oz
Condenser..........1.0 oz
Evaporator.........1.5 oz
Accumulator........1.0 oz
Hoses..............1.0 oz
Thanks for the replies. The reason I am replacing the expansion valve. We were preparing to go on a couple extended trips last summer. The dash a/c was not cooling when I bought the coach. I took it to a local auto mechanic near me that I have used a few times and like. To see if maybe it just needed charged. After he hooked up his gauges he tried to add a little R134a and quickly told me that there was a blockage in the system. He told me that he was confident the expansion valve was blocked. I think he said the high side was too high and the low side was too low. As far as the pressures. Said he could change it but wasn't sure how my dash came apart to get to it. He was also very busy and just got me in as a favor. I just ran the generator on my trips. My expansion valve is next to the evaporator under the dash. I do appreciate all the information on this it is very helpful.
After rereading your post Scott I realize that you were saying the receiver dryer is before the expansion valve in the direction of flow. Not that the expansion valve is near it in proximity.
Tom where exactly did you find your TXV and how much of your dash did you have to remove to get to it? Also the link in the original post is broken for me. Anyone else experiencing a problem?
Yes. Its mounted at the condenser at the rear of the coach then 30 feet of line
dash air expansion valve (https://www.foreforums.com/index.php?topic=27441.msg224665#msg224665)
Mine is in the same spot as Craneman's. My dash is the newer version. Barry Beam had an old thread with great pictures for his 2003 u320. Mine was exactly like his. The broken link is for the picture at the bottom about the Pag oil. I'm not sure why it showed up like that and don't know how to fix it.
Location of the Dash Air Expansion Valve on a 2003 U320 (https://www.foreforums.com/index.php?topic=22360.0) Hopefully this will add a link to Barry Beams thread. I really am not sure how to do this we will see if it works. Tom
Very helpful and thank you. Do you know what O-rings are required with the 1600 expansion valve?
I ordered this o ring kit. BUSY-CORNER Oring Kit 270 Pieces 18 Sizes SAE Inch Car Air Conditioning A/C O Ring Seals Rubber O-Rings Green Amazon.com: BUSY-CORNER Oring Kit 270 Pieces 18 Sizes SAE Inch Car Air... (https://a.co/d/cZoGkPL)
Tom,
If you decide to go the full diy approach with your own gauges and vacuum pump, you might also want to buy the kit that is to keep the gauge seals in top order. I know this is a 1 time project at the moment, but I bought a gauge set once that one of the sealing ring in one of the 134a adapters was bad...Luckily I scavaged an old gasket out of an old broken adapter, if not I would have .had to wait to finish the job until I could get a new gauge gasket set. This or one like it.
Amazon.com: Eboxer 71Pcs A/C Air Condition Repair Kit Repair Tool, with... (https://www.amazon.com/Eboxer-Condition-Removal-Install-Gaskets/dp/B08R6W766N/ref=sr_1_31?crid=6OSN0TSET5D6&dib=eyJ2IjoiMSJ9.IS5B2ncipz0PTzKO3GKv-MuSCCHm3jZFUeZEkEKYZ0ELE1zysl_Uz8Zs3vrbTm3xueSSl97WDWB8Pfv4FlBswA.XNfDa5iqs95Ck4aFO2NSfQojZLZWnW6Q_IDttFfX8Pw&dib_tag=se&keywords=ac+gauge+set+o%27rings&qid=1704981363&s=industrial&sprefix=ac+guage+set+oring%2Cindustrial%2C206&sr=1-31)