Automotive Air Conditioning Information Forum

Hello,

Few questions…

I have 9 vehicles I take care of (4 I drive, wife has 2 and 3 kids each have cars). Most are older from 2002-1016. I do all my own maintenance and have since I was a kid. This is not my profession. I’m on this forum because I have always taken care of my own AC issues. Recently I purchased a Mastercool 69110 recovery machine, Snap-on manifold and a TIF9015 electronic scale. These are all used items. I already had an older manifold set that the knobs have fallen apart and a vacuum pump. It was time to be more professional with my AC work…..

Generally my approach has been to remove R-134 from the system, evacuate, see if it hold the vacuum, then replace the R-134 with the spec for the car. So far I haven’t had to replace any parts over the years. Just lucky I guess.

I’m new to using the Recovery machine but I think I fumbled through it. I used the Recovery machine on my 2002 today and pulled all the R-134 into the 30# tank. I pulled about 16oz out and spec charge is 600g or 21+ ounces. I evacuated the system. Since I needed another 5+ oz of R-134 my solution was to add 5 oz to the 30# tank. I then added that back to the system directly into the manifold. The AC works great. I evacuated the empty tank and put everything away for the next job. Last summer both my wife’s vehicles had issues and this was my approach….minus the recovery machine…

First/Second question: Is there a better way than my plan to add the shortfall of R-134 to the 30# tank? I didn’t use the recovery machine to pump back in the vehicle. Is that the correct approach? My reuse of R-134 is limited to reintroduction into the same vehicle I pulled it from to be clear. I am certainly not authorized nor need the larger tanks of R-134 so I’m limited to the 12 oz variety.

Third question: The scale appeared to be kind of flaky. My initial pull from the car the gauge went up steadily but later when the rate was slower it appeared the scale would stop and show no progress. I’d lift the tank and set back down and the extra weight would show up. This was especially annoying putting the R-134 back in the car and the scale would stagnate and show nothing happening only to lift the tank and reset and the scale would be higher than where it stagnated. I eventually transferred the correct amount. Anyone have experience with this scale? Is this normal? It’s just annoying when the scale stops. It’s like when the rate of transfer drops below a certain value it ceases to sense the change. Just wondered. I thought about buying a new scale but I think i can make it work.

Thanks in advance!

jfred16 wrote: ↑Mon Sep 23, 2024 5:01 pm I’m on this forum because I have always taken care of my own AC issues. ....... It was time to be more professional with my AC work…..

Generally my approach has been to remove R-134 from the system, evacuate, see if it hold the vacuum, then replace the R-134 with the spec for the car. So far I haven’t had to replace any parts over the years. Just lucky I guess.

I'm confused. Your post sounds like you periodically recovered your refrigerant just to do a check for holding vacuum and to check if the refrigerant amount matched specification??? If so, I've never heard of such a practice, and definitely would avoid touching a system that was cooling the occupants properly.

Only messing with AC system when not working well.

Both of my wife’s vehicles (2007 Aspen and 2104 VW CC) stopped blowing cold air this summer. Little cooler than ambient but not cold. Wife not happy. My 2002 VW Passat seems to need a top off each year. That’s just what I did. The difference is now I have a recovery machine instead of evacuating system by other means. I don’t add refrigerant without knowing how much is in the system.

I’m going to guess many on here have access to 30# R-134 cylinder and just remove old R-134 and replace with new. I can’t go that route. Unless I hear a better technique I’ll just add R-134 to my recovery tank to make up for lost R-134 from a 12oz can then refill system from the recovery tank.

Be careful that you are not running low on oil. If there is a slow leak, usually you are losing small amounts of oil as well. Look for “wet” areas at fittings, joints, etc

I don't see anything fundamentally wrong with you re-using your own refrigerant. I have done similar on my vehicles with both R-12 and R134a.

Yes, I still have one truck on R-12.

Such re-use is permitted by law

I sure would not throw it away or give it to a shop.

tbirdtbird wrote: ↑Wed Sep 25, 2024 9:32 am Be careful that you are not running low on oil. If there is a slow leak, usually you are losing small amounts of oil as well. Look for “wet” areas at fittings, joints, etc

I did wonder about that. No wet spots I can see..

That recovery machine is supposed to pull out oil, i thought, and separate. It didn't pull any oil out of my 2002. Maybe I should add some oil?

jfred16 wrote: ↑Thu Sep 26, 2024 4:08 pm That recovery machine is supposed to pull out oil, i thought, and separate. It didn't pull any oil out of my 2002. Maybe I should add some oil?

As far as I know - and I'm not an AC professional - very little oil will be pulled out by the vacuum, either with a recovery machine or when pulling a vacuum prior to filling a system.

As a science professional, that also makes sense, as the refrigerant oils have low volatility.

A little late, but I do want to add a few comments to this discussion.

jfred16 wrote: ↑Mon Sep 23, 2024 5:01 pm Recently I purchased a Mastercool 69110 recovery machine, Snap-on manifold and a TIF9015 electronic scale. These are all used items.

All are good, professional-grade pieces of equipment.

jfred16 wrote: ↑Mon Sep 23, 2024 5:01 pm I’m new to using the Recovery machine but I think I fumbled through it. I used the Recovery machine on my 2002 today and pulled all the R-134 into the 30# tank. I pulled about 16oz out and spec charge is 600g or 21+ ounces. I evacuated the system. Since I needed another 5+ oz of R-134 my solution was to add 5 oz to the 30# tank. I then added that back to the system directly into the manifold. The AC works great. I evacuated the empty tank and put everything away for the next job. Last summer both my wife’s vehicles had issues and this was my approach….minus the recovery machine…
First/Second question: Is there a better way than my plan to add the shortfall of R-134 to the 30# tank? I didn’t use the recovery machine to pump back in the vehicle. Is that the correct approach? My reuse of R-134 is limited to reintroduction into the same vehicle I pulled it from to be clear. I am certainly not authorized nor need the larger tanks of R-134 so I’m limited to the 12 oz variety.

Your approach sounds good, if not a bit unconventional.You probably already know this, but your Mastercool machine is for recovery only (refrigerant and oil) and isn't intended for evacuating and recharging a system as an RRR machine could do.

Why go through evacuating your 30-pound recovery tank each time you're done using it, and why add a refrigerant amount to the tank exactly equaling the amount needed each time? Presuming your recovery tank doesn't leak, you could add the contents of two, three, or more of the small 12-ounce cans so that you wouldn't have to figure exactly how much refrigerant you'll need in the tank each time. Keeping the recovery tank partially charged in that way means that you'll be ready to weigh-in a precise amount of refrigerant the next time you need to recover, evacuate, and recharge a system.

jfred16 wrote: ↑Mon Sep 23, 2024 5:01 pm Third question: The scale appeared to be kind of flaky. My initial pull from the car the gauge went up steadily but later when the rate was slower it appeared the scale would stop and show no progress. I’d lift the tank and set back down and the extra weight would show up. This was especially annoying putting the R-134 back in the car and the scale would stagnate and show nothing happening only to lift the tank and reset and the scale would be higher than where it stagnated. I eventually transferred the correct amount. Anyone have experience with this scale? Is this normal? It’s just annoying when the scale stops. It’s like when the rate of transfer drops below a certain value it ceases to sense the change. Just wondered. I thought about buying a new scale but I think i can make it work.

Something isn't right with your scale. First, verify that the battery is fresh and up to full voltage by testing it with a VOM. If there's any doubt, simply replace the battery with a new one.
If the battery proves to be good, consider sending the scale back to the manufacturer for repair, re-calibration, and a function check.