A/C Manifold Gauge Sets

[Wamsutta]

What are you guys using and what do you prefer?

The A/C compressor in my car grenaded at the hottest part of the year.

I'm going to install all the parts myself, but I figure for the cost of hiring a shop to recharge the system, I could get an A/C manifold gauge set and do it myself. All I would need is a set that reads R134A. Also if you have any tips on flushing out the system, I would appreciate that too.

 

[engineer2]

I use whatever is cheap. HF should be fine. Center dash vent temperature tells the tale. Should be in the 40's F. If parts or debris have contaminated the system, more thorough disassembly and flushing is needed. Pull down to 400 microns vacuum or better. A cheap Supco (or Amazon) vacuum gauge is adequate.

 

[Nocturnal]

I recently bought the MasterCool Manifold Gauge Set from Amazon and was happily satisfied.

 

[DGersic]

What are you guys using and what do you prefer?

The A/C compressor in my car grenaded at the hottest part of the year.

I'm going to install all the parts myself, but I figure for the cost of hiring a shop to recharge the system, I could get an A/C manifold gauge set and do it myself. All I would need is a set that reads R134A. Also if you have any tips on flushing out the system, I would appreciate that too.

You need more than gauges. You’ll need at least a vacuum pump and a micron gauge.

You can buy A/C flush at NAPA. You’ll need to replace more than just the compressor. Buy an O ring set at O’Reillys, and a bottle of PAG oil to lube the O rings.

 

[signcrafter]

I recently needed to replace a compressor and recharge the system and my pump and gauges were in a different state. Being that they are probably 15 or so years old I just bought new ones to get the job done. I ordered this kit from amazon and have used it twice now and will be using it again tomorrow and have been happy with it so far. https://www.amazon.com/dp/B0F6Y83BB7?tag=atomicindus08-20.

Rockauto has A/C kits that come with a compressor, condenser, expansion valve, dryer, oring kit, and pag oil for decent price and I've ordered half a dozen or so and haven't had any issues yet. You will need to vacuum the system down once you open it up. As for flush any auto parts stores sell it but it's expensive. I just bought a gallon from autozone for 60 bucks which is a lot cheaper then buying the quart size ones, it doesn't go very far and I usually have used 2 quart jugs in the past which comes out more then the 60 bucks for the gallon. I have this flush gun, https://www.amazon.com/dp/B0FSZ3WPZ9?tag=atomicindus08-20.

 

[Bill Bowman]

I would bet there's going to be a bunch of swarf floating around in your system. Will a flush get it all? Maybe. Maybe not. Best practice is to replace stuff, rather than try to "clean" it out. Some areas inside lines, and parts don't always flush out as planned. Ask Toyota about how that works out.

 

[L.Cheapo]

All of my A/C tools are Yellow Jacket. Not cheap, but high quality and American made.

When I had a question, I called them. The nice lady who answered the phone transferred me to the engineer who designed the tool, who was obviously able to answer my question. That has value to me.

 

[rsanter]

You also need a vac pump

 

[Dakotadadv8]

What are you guys using and what do you prefer?

The A/C compressor in my car grenaded at the hottest part of the year.

I'm going to install all the parts myself, but I figure for the cost of hiring a shop to recharge the system, I could get an A/C manifold gauge set and do it myself. All I would need is a set that reads R134A. Also if you have any tips on flushing out the system, I would appreciate that too.

Did same 2 years ago. Napa AC kit, compressor, dryer, evaporator, pag oil. Already had Robinair vacuum pump, SO gauge, and SO leak detector. DIY 2 vehicles great learning experience check and repair in May before it gets hot. Tool investment was pricey but figured 2 vehicles paid for itself. Learning experience invaluable IMHO.

 

[Wamsutta]

Did same 2 years ago. Napa AC kit, compressor, dryer, evaporator, pag oil. Already had Robinair vacuum pump, SO gauge, and SO leak detector. DIY 2 vehicles great learning experience check and repair in May before it gets hot. Tool investment was pricey but figured 2 vehicles paid for itself. Learning experience invaluable IMHO.

You changed the evaporator instead of the condenser?

 

[Dakotadadv8]

Crazy was leaking. Also condenser. So far so good.

 

[charbar]

Tools you will need at a minimum to do a halfway correct job are:

Gauge set
Vac pump
Flush gun
Scale

If that is something you were unaware of then you might want to do some more research on a/c repair before you tackle this job. Just trying to save you from possibly grenading another compressor or ending up with lackluster results.

 

[Junkman]

You also need a bottle of nitrogen. I have had systems that would hold a vacuum, but not pressure. I only work on R12 systems in old cars, so I am very particular that everything is done the first time correctly. I also only work on my own cars, and a good friend's if I am in the mood to do the work. If it has been converted, I won't work on it, nor will I if someone else has had their hands in it before. When I first got into doing A/C work over 60 years ago, it was quite crude, but we always got the job done. The more that I learned, the more tools I needed. In my opinion, there is no way to do a "halfway correct job" and have it last the test of time. Do it correctly or don't do it at all. No sense in wasting money on parts, tools, and refrigerant unless you know what you are doing or have someone who does teach you.

 

[bob smith1]

What does "grenaded" mean to you? If the compressor truly made change, you have a bigger issue than just finding gauges. At a minimum, likely just replace the condenser because you will never get it cleaned out.

Picture of compressor oil in the sun will help in the story.

 

[Hohn]

I use whatever is cheap. HF should be fine. Center dash vent temperature tells the tale. Should be in the 40's F. If parts or debris have contaminated the system, more thorough disassembly and flushing is needed. Pull down to 400 microns vacuum or better. A cheap Supco (or Amazon) vacuum gauge is adequate.

I had the HF and tossed it after a couple uses because of the low quality valves leaking.

The Robinair unit was still somewhat reasonable in cost and a notable upgrade. I'm sure the pro units (yellowjacket?) are better, but not better enough for my uses to justify the premium.

 

[bob smith1]

No spam, just brand I trust. Actually I run probes for everything but the Testo 550, if you can find that on sale, is a solid choice. I haven't once regretted ditching the std manifold but I do have an SMAN on standby.

NAVAC N2DX Flex-X Digital Manifold Gauge with HD Color Interface

The N2DX FLEX-X Manifold Gauge is the industry's first gauge with HD Color Graphic Interface. It delivers Class 0.4 accuracy with digital reading, real-time visuals, and advanced animations through its innovative graphical user interface. With a rechargeable battery lasting up to 100 hours and...

trutechtools.com

 

[Wamsutta]

Tools you will need at a minimum to do a halfway correct job are:

Gauge set
Vac pump
Flush gun
Scale

If that is something you were unaware of then you might want to do some more research on a/c repair before you tackle this job. Just trying to save you from possibly grenading another compressor or ending up with lackluster results.

What is the scale for? I know they weigh the refrigerant for a residential application so that they know how much refrigerant to charge the customer, but when would you use a scale for automotive?

 

[bob smith1]

What is the scale for? I know they weigh the refrigerant for a residential application so that they know how much refrigerant to charge the customer, but when would you use a scale for automotive?

Every system should be weighed in, regardless of type. However, automotive is notorious for "half ***" and "beer can cold".

But if you are lucky enough to get the small cans to hit your charge number, you can do it that way!

You don't have to overthink the scale. A good fishing scale works!

 

[signcrafter]

What is the scale for? I know they weigh the refrigerant for a residential application so that they know how much refrigerant to charge the customer, but when would you use a scale for automotive?

You charge automotive AC by weight also. There should be a sticker when you open your hood that says type and amount of freon to use.

 

[Buckaroo5]

What is the scale for? I know they weigh the refrigerant for a residential application so that they know how much refrigerant to charge the customer, but when would you use a scale for automotive?

Yes, you need to know the weight of refrigerant added - you cannot just fill to achieve a specific pressure with modern refrigerants. A cheapy HF digital scale will do. You need to study up on this....lots to know. As others have said, if you have shrapnel in your system from the compressor exploding, you absolutely need to get it all out or it will just blow up your new compressor and you will get to do the whole job again. Replace the condenser and the receiver/dryer.

 

[Wamsutta]

Yes, you need to know the weight of refrigerant added - you cannot just fill to achieve a specific pressure with modern refrigerants. A cheapy HF digital scale will do. You need to study up on this....lots to know. As others have said, if you have shrapnel in your system from the compressor exploding, you absolutely need to get it all out or it will just blow up your new compressor and you will get to do the whole job again. Replace the condenser and the receiver/dryer.

Is that for those giant canisters that the HVAC guys use? I was just going to use the little 12 ounce cans from Walmart and rely on the pressure readings to know when the system is full. Is there any way to weigh those little 12 ounce cans?

 

[Dakotadadv8]

HF scales are cheap

 

[bob smith1]

Is that for those giant canisters that the HVAC guys use? I was just going to use the little 12 ounce cans from Walmart and rely on the pressure readings to know when the system is full. Is there any way to weigh those little 12 ounce cans?

LMFAO........ I dunno, 12oz maybe.......just maybe......

I think you're in deep here and prob should phone a friend.

 

[whateg01]

Is that for those giant canisters that the HVAC guys use? I was just going to use the little 12 ounce cans from Walmart and rely on the pressure readings to know when the system is full. Is there any way to weigh those little 12 ounce cans?

How are you going to know when you have put in 5.5 oz out of a 12 oz can?

 

[Wamsutta]

How are you going to know when you have put in 5.5 oz out of a 12 oz can?

The Google robot says to empty two 12 ounce cans and use a kitchen scale to weigh the 3rd one. I guess it wouldn't kill me to weigh all three. Sounds reasonable. Gives me a good excuse to buy one of those scales because I've been wanting to weight a bottle of 2-cycle oil.

 

[lolaetype]

I've been using the same set of HF gauges for around 25 years. They work fine. I also bought one of their vacuum pumps that run off of compressed air. it works fine too.

As for how much to add, be aware that if you have converted an older car that used R-12 you use a lesser amount, by weight, of R134a. See attachment.

R12 to R134a Conversion Chart & Formula - techtown

R12 to R134a Conversion Chart & Formula

www.techtownforum.com

Fortunately, the one car I have that has been converted has charging specifications that give maximum high pressure readings at various ambient temperatures. I use that data and have never had a problem.

 

[Buckaroo5]

Is that for those giant canisters that the HVAC guys use? I was just going to use the little 12 ounce cans from Walmart and rely on the pressure readings to know when the system is full. Is there any way to weigh those little 12 ounce cans?

Yes, you weigh the little cans. You are going to likely add less than 2. Weigh it before you start with your gauge hose attached and then watch the scale as it feeds in to get the amount added.. Obviously, you want to take the tare weight after you have purged your line. Don't depend on the 12 oz can label weight - you may not be able to get it all out of the can.

You cannot use the pressure to determine the correct fill - that may have worked for R-12 but for the newer refrigerants like R-134a, it is not accurate enough. Too much or too little will affect your AC system performance.

As I said before, there is a lot to know about this. Many years ago I tried to replace a compressor that had blown without knowing enough. I had a guy helping me that knew more than me but still not enough. It didn't work and I traded in the car with the AC not working. That was my rocky intro to automotive AC work.

 

[Buckaroo5]

The Google robot says to empty two 12 ounce cans and use a kitchen scale to weigh the 3rd one. I guess it wouldn't kill me to weigh all three. Sounds reasonable. Gives me a good excuse to buy one of those scales because I've been wanting to weight a bottle of 2-cycle oil.

You need to know how much R-134-a is in your specific system. It should be printed on a sticker on the inside of the hood. By the time you buy the tools, the compressor, condenser, receiver dryer, gaskets. PAG oil and other bits & pieces you are going to have a fair amount invested in this job which may not be successful. Maybe just bite the bullet and have a shop do it,

 

[Firebrick43]

You cannot use the pressure to determine the correct fill - that may have worked for R-12 but for the newer refrigerants like R-134a, it is not accurate enough. Too much or too little will affect your AC system performance.

That is not true for R134.

I have not seen a vehicle manufactures manual yet that didn't have pressure/temp charts and tables for OS/Temp/RH/discharge temp yet.

Snippets from a GM manual





Weight is an easy way for an initial fill and some places with recovery machines may do repair or top off a system via recovery and weight back in, but its to avoid math and reading temps not absolutely imperative to do it that way. Systems with accumulators might be hard to use Superheat or sub cooling, but that is more in modern residential heat pump systems.

 

[Buckaroo5]

I have used those tables primarily for verifying correct system pressures during diagnosis. Although lots of folks top off their systems (and I have too), I have always weighed the refrigerant in when doing a complete system recharge. It really is not that difficult and it was the way I was taught to do it.

 

[Firebrick43]

I have used those tables primarily for verifying correct system pressures during diagnosis. Although lots of folks top off their systems (and I have too), I have always weighed the refrigerant in when doing a complete system recharge. It really is not that difficult and it was the way I was taught to do it.

I wasn't talking about if it was "Difficult" or not. I was talking about your very incorrect statement "You cannot use the pressure to determine the correct fill" for R134.

There is a difference about preferred ways and just spouting off incorrect BS that is absolutely untrue

 

[Buckaroo5]

I wasn't talking about if it was "Difficult" or not. I was talking about your very incorrect statement "You cannot use the pressure to determine the correct fill" for R134.

There is a difference about preferred ways and just spouting off incorrect BS that is absolutely untrue

As I said, it is not that difficult to do it the right way. And the "math" is not that hard either.

 

[Firebrick43]

As I said, it is not that difficult to do it the right way. And the "math" is not that hard either.

LOL.

You link a video that talks about indiscriminately adding a half pound of refrigerant and somehow illogically conflate that as the same as using temp,RH, and pressure measurements and comparing those measurements to manufacture’s supplied chart?

That is full on troll 🧌

 

[Buckaroo5]

LOL.

You link a video that talks about indiscriminately adding a half pound of refrigerant and somehow illogically conflate that as the same as using temp,RH, and pressure measurements and comparing those measurements to manufacture’s supplied chart?

That is full on troll 🧌

The pressure chart that you referenced has a range that is wide and humidity indicies that are way approximate and you are trying to hit a fill amount that could be as low as 11 oz on pressures that are jumping around as you try and measure them? Oh, and do you get your manifold gauges calibrated? Of course, not....no one does. You are suggesting a very old automotive practice that was once correct but is no longer applicable. Welcome to the 21st century. I was not trolling - you are the one that went off on a simple statement of mine that was not central to the topic when I was just trying to help the guy. That, my friend, is trolling. I was trying to figure out a way not to have to say it but you are flat out wrong. Sorry I had to be the 70 year old whippersnapper.

 

[Firebrick43]

The pressure chart that you referenced has a range that is wide and humidity indicies that are way approximate and you are trying to hit a fill amount that could be as low as 11 oz on pressures that are jumping around as you try and measure them? Oh, and do you get your manifold gauges calibrated? Of course, not....no one does. You are suggesting a very old automotive practice that was once correct but is no longer applicable. Welcome to the 21st century. I was not trolling - you are the one that went off on a simple statement of mine that was not central to the topic when I was just trying to help the guy. That, my friend, is trolling. I was trying to figure out a way not to have to say it but you are flat out wrong. Sorry I had to be the 70 year old whippersnapper.

You have the hyperbole factory next door pulling double shift huh.

R-134 only spent a few years in the 20th century. The manual I pulled the charts from were well in the 21st century.

And where are you getting 11oz? From your hooky video above talking about a Chevy cobalt @0:30 ??

If your gauge bounce around that you can’t get saturated temp/psi readings to a degree or two maybe you should invest in new ones.

You were not trying to help, you were gate keeping on a DIY forum with incorrect info to boot

Maybe just bite the bullet and have a shop do it,

 

[Buckaroo5]

You have the hyperbole factory next door pulling double shift huh.

R-134 only spent a few years in the 20th century. The manual I pulled the charts from were well in the 21st century.

And where are you getting 11oz? From your hooky video above talking about a Chevy cobalt @0:30 ??

If your gauge bounce around that you can’t get saturated temp/psi readings to a degree or two maybe you should invest in new ones.

I am happy with the info I presented. It was fun, but I have more important things to do than continue this back and forth so I am going to stop....Over and Out!

 

[bob smith1]

I wasn't talking about if it was "Difficult" or not. I was talking about your very incorrect statement "You cannot use the pressure to determine the correct fill" for R134.

There is a difference about preferred ways and just spouting off incorrect BS that is absolutely untrue

Actually, you can't and he is right!!! That's like asking 'what temp does water boil?'...... Not enough information to get the right result!

You do NOT, EVER, properly charge ANY system, regardless of refrigerant, whether R-12, or R1234YF, by pressures alone. Those values are provided as a GUESS for quick diag and maybe topping one off. You would need SH/SC values, temp splits, ambients, fan speeds, etc, etc.

Car systems are all over the place and all you need to do is put a piece of cardboard in front of the condenser if you want to see a higher head pressure.

I've examined COUNTLESS systems that were over charged, even by job idiots, because they think the pressures tell all. They don't! Hell, I did a complete system vac and recharge recently, weighing in, and I STILL stopped the charge short because I could tell the behaviors were indicating a possible system restriction. I check some service bulletins, and sure enough, they are known to try to plug the rear air orifice. Most would have filled it right up with the "right charge". It wasn't the right call.

If someone just looks at those charts, one would conclude that somewhere between 0-100% humidity, with a mystery evap temp, we can conclude the head pressure should be between like 60-125psi....lol

 

[Firebrick43]

Actually, you can't and he is right!!! That's like asking 'what temp does water boil?'...... Not enough information to get the right result!

You do NOT, EVER, properly charge ANY system, regardless of refrigerant, whether R-12, or R1234YF, by pressures alone.

Where did I ever say pressure only? That was me quoting buckaroo that was stating only weighting in a charge is the only way to do so and was trying to straw man his argument by over simplifying what is needed. Quote me because I didn’t say tha you can do it “with pressure only”. It’s all in post 29

Those values are provided as a GUESS for quick diag and maybe topping one off. You would need SH/SC values, temp splits, ambients, fan speeds, etc, etc.

I mentioned all that. Fan speed for a vehicle is full speed

But you even say “maybe topping off” is ok.

Logic would say if you make the argument that only by weight is the only correct method, then only recovering all the charge and reweighing it back in is the only acceptable process.

All the rest of the **** of you finding what other idiots did or didn’t do is immaterial to the issue. Many can’t use a scale correctly either or let a lot of the charge escape unhooking lines after they weighted it in

 

[bob smith1]

I have used those tables primarily for verifying correct system pressures during diagnosis. Although lots of folks top off their systems (and I have too), I have always weighed the refrigerant in when doing a complete system recharge. It really is not that difficult and it was the way I was taught to do it.

I wasn't talking about if it was "Difficult" or not. I was talking about your very incorrect statement "You cannot use the pressure to determine the correct fill" for R134.

"Logic would say if you make the argument that only by weight is the only correct method, then only recovering all the charge and reweighing it back in is the only acceptable process."

Congrats, you found the ONLY right method! If you were in the trade, you would not have said the BS you did. You went over the top to insult someone for no reason, just for him recommending the only correct method!

 

[Firebrick43]

I wasn't talking about if it was "Difficult" or not. I was talking about your very incorrect statement "You cannot use the pressure to determine the correct fill" for R134.

Yes. The above quoted still doesn’t say “pressures alone” like you falsely claimed I said and you insult yourself by not quoting where I stated you needed temps, and RH, and even talked about superheat and sub cooling in post 29

You do NOT, EVER, properly charge ANY system, regardless of refrigerant, whether R-12, or R1234YF, by pressures alone.

I didn’t come to the conclusion that weighting in is the only right method. I was pointing out your contradictory statement, there is a word for telling people there is only one way to do something and then doing the opposite yourself.

You do NOT, EVER, properly charge ANY system, regardless of refrigerant, whether R-12, or R1234YF, by pressures alone. Those values are provided as a GUESS for quick diag and maybe topping one off. You would need SH/SC values, temp splits, ambients, fan speeds, etc, etc.