Got it! Thanks for all the input! 9 cans on the way. Now I need to figure out all this ac stuff. No doubt more questions will come up in the weeks ahead. You can dang sure know that at the next major, the compressor will get tied back rather than being dropped with the engine. This ac PIA (and $) far exceeds the issues around a compressor tie back. Image Unavailable, Please Login
Actually if you buy the equipment (pm sent) and have r12 ..it isn't bad..better than a crazy rear window or scratch body Sent from my moto g power using Tapatalk
IIRC, the R12 system uses a mineral oil and the 134a system uses a synthetic oil. The two oils are not compatible. I know that 134a gas absorbs the synthetic oil and provides system lubrication as it circulates with the refrigerant. Thus, pulling a vacuum will remove the gas and absorbed oil, but I am not sure of the quantity of residual oil left in the system to be concerned with. I am not sure if mineral oil interaction with R12 is the same. EDoug
Doug, are you saying that the liquid oil is in a gaseous state when under pressure? As I understand it, mixing the oils forms a gel. Hard to imagine ‘all’ the oil coming out under vacuum. Perhaps just an insignificant amount of gel forms when switching oil types under vacuum. Question: When I refill with R12 after pulling a vacuum, do I need to add more R12 oil? How much? How to know?
No you shouldn't need to add oil unless you are replacing some components Did you get my Pm Sent from my moto g power using Tapatalk
Yes, thanks. Still mulling over the equipment options. Once I get the r12 in hand, I’ll be ready to buy. I’ll check back with some ideas. The kits with pump and gauges etc seem a good option, but the YJ gauges look to be top quality. There are many gauge options and the info infers(?) that only ‘some’ of them are suitable for R12. Perhaps the gauge’s pressure range? Amazon rarely shows a quality pic of the gauges - usually you can’t see their range etc. BTW: Do you fill the system to a specified pressure, or with a specific number of ounces by weight? Image Unavailable, Please Login
I buy all my Yellow Jacket HVAC and R fittings, gauge sets and hoses, etc. from SupplyHouse.com. Yellow Jacket is very high quality and the only brand I buy. You might want to check them out for price comparison. Those that mess with both R12 and 134a will keep a separate dedicated vacuum pump hose for each gas to prevent cross-oil contamination of mineral and synthetic oils. Like I said, I know that with 134a my vacuum hose is a bit oily after service. I don't think it is a pressure thing, maybe a suspension thing?? Any oil that is absorbed into the refrigerant will be vacuumed out with the gas. I believe that the specified oil charge for the compressor is a larger volume, and thus a residual, but I don't know by how much. Others on this forum may know the residual in the system to be expected, but more importantly, what the volume and type of oil charge for the compressor is. So pull a vacuum on your system to fully evacuate, release to 0 psig, and then add any needed oil charge to the compressor with the correct type of oil. I have only needed to add R12 to the TR over the years. The system has never been opened, so that is why I can not tell you if the TR compressor oil acts the same. EDoug
Thanks Doug, It sounds like most everybody agrees that Yellow Jacket is one of the best. Interesting: Yellow Jacket 42007 sells on Amazon for $123.29, but sold by and ships from JB Tools. Going directly to the JB Tools web page and they sell it for $101.90 (free shipping). Dang…. Bezos is getting a helluva cut for listing it on amazon. Keeping separate manifolds etc for the incompatible refrigerant/oils is a great idea. This guy did a good vid and answered a lot of my questions on gauges:
Yes…. Two of them. See post #32 as shown above. Apologies if I missed something. I tried to answer via the public forum.
Sorry i actually missed it ..glad you got the info I think you will find it much easier than you may be thinking Vacuum, check for leaks, refill using scale ..done i Sent from my moto g power using Tapatalk
For both R12 and 134a systems normally a small amount of oil leaves the compressor and circulates thru the system. When the refrigerant is a gas, the oil is suspended as aerosol droplets, and a high gas velocity is needed to keep it moving. When the refrigerant is liquid, the oil is miscible and is dissolved in the refrigerant/oil mixture. When the system is not operating, eventually the oil droplets will fall out of the gas phase and on to the tubing walls. So when you pull a vacuum, do it slowly and you won't disturb the settled-out oil and remove a significant amount along with all the gas, and your vacuum/charging hose will stay cleaner. Pulling a vacuum quickly or venting the residual refrigerant charge to atmosphere causes rapid and violent boiling of the liquid refrigerant and high gas velocities which will surely carry a lot of oil with it. Vacuum for a long time, perhaps overnight to ensure you remove all the moisture in the system. Invest in a ~$200 micron gauge and evacuate your system down to <200 micron, and when you valve off the vacuum pump it should not rise to over 500 micron in an hour's time. Then you can be sure it's leak tight and ready for adding the right amount of refrigerant.
FWIW, I'm running R-152a in my 328 and I had it in my Benz. This is the canned air and I bought it at Costco for almost nothing. It's equal to if not better than R12 when you get the conversion amount correct. Getting it from the can to the system is the hardest part but it's worth the time and effort considering the cost availability. Craig
Great explanation. Your engineering background is obvious…. but I am curious, do you work with refrigeration design? Thanks for taking to time to explain that! PS: have not yet purchased a pump. Any tips on what to look for in a pump that will allow for a slow initial pull? Do they have a valve or speed control or ?
My pleasure! In graduate school I measured evaporative heat transfer coefficients vs oil content in the “new” at the time r134a. Currently I work on engineering reviews of satellites and space science instruments. My main thermal project is insulating my garage and installing a mini split heat pump haha. Work is all spreadsheets and PowerPoint charts so my garage and BBi are the fun hands on work for me. The vacuum pump style won’t matter for slow initial pump outs, you want to just very slowly crack open the service valves where the hoses attach. Then gradually open them over the next 15 minutes. You will hear the sound of the pump changing as it’s loaded with high gas flow or not, and base your opening speeds on that. Sent from my iPhone using FerrariChat
One disclaimer, as you know working on ac systems can be complicated and dangerous. I recommend watching at least 10 YouTube videos on the basics before connecting anything to your car Leak check your service hoses and connections before attaching anything to the car. Determine if you have a check valve in the service hose or not. There’s a million subtle things which make this area of work interesting and complicated. Sent from my iPhone using FerrariChat
Thanks John, Lots to learn, for sure. Many ‘iffy’ youtube vids, but some good ones as well. This is a task where it would be really good to get ‘hands on’ training from a very knowledgeable tech. Appreciate your input!
They make a top tap but you have to cut the plastic pipe a bit. It works well. I try and install it by weight but on the 328 it's difficult. Craig
Vincenzo, if the ship has not sailed yet and your system had not been opened, maybe you can try a little old school stuff in the interim. Running your engine with the AC on, look at your sight glass and observe the R12 state. If you see a gaseous state with lot of gas bubbles, charge in a little R12 (without introducing any air) and see if the bubbles diminish to a liquid state at the sight glass. EDoug Image Unavailable, Please Login Image Unavailable, Please Login
Thanks EDoug, unfortunately though, the entire system was drained when the engine was pulled out for the major. Still working on this… but very slowly. Next up is the vacuum pump selection. Right now, I am super busy on hardening the home for this crazy wildfire season. It is incredible, super dry out here in the west. Lots of 100+ degree temps, low humidity and high winds every day. Now surrounded by several huge, out of control wildfires (each about 40 miles away). Hopefully too far away to directly affect my location. Just watched a brush fire last week several hundred yards away from my back door. Thankfully, the FD got it out right away. Now Building a shed to replace the existing vinyl version. Steel frame, cement board siding, stucco, copper roof…. Also designing some fine water mist fire fighting systems in my mind…. Have a cool idea in mind for an eductor powered fine water mist backpack system. Eager to start that, but the shed comes first. So far, over 400 ss rivets. Another 300 on order. Sorry to digress - but now you know why I am so slow. If anybody out there has fire eye experience, please PM me. Looking for a way to automatically trigger a FWM system.
Vincenzo, that is quite an eye opener! First things first, please stay safe. Back in the day, I seem to remember that we did have some areas where infrared detectors were used, but it has been a long time. EDoug
