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DIY equipment recommendation

edvmemphis on Wed July 09, 2008 9:18 AM User is offline

I want to jump in to DIY auto A/C work and am looking for recommendations on equipment. It won't get the heavy use that a shop will give it, and I don't need to do procedures quickly (I guess that's the usual story for DIYers). Of course I want to keep price down, but don't want junk. I will work on my 2 cars, family, friends. For now, I'm looking for high-low gauge set with hoses, can tap, and a decent thermometer. On round two for systems that have been opened, a vacuum pump. (Maybe later a scale for larger tanks and eventually a recovery system.)

Any recommendations? Specific make and model would be welcome, as well as general wisdom on features and capabilities. Am I missing anything major?



Ed V
Memphis, NY

Edited: Wed July 09, 2008 at 9:39 AM by edvmemphis

webbch on Wed July 09, 2008 10:47 AM User is offlineView users profile

Go to the site sponsor - They sell an excellent DIY kit that will let you hit the ground running. In addition to that kit, You'll then start looking at......
1) Refrigerant recovery machine to recover refrigerant prior to vacuuming the system - the dry ice method works, but I found it to be a bit of a PITA.
2) 30 Lb tank of refrigerant - FYI, the autoparts stores sell R134a in 30 Lb'ers, but normally keep them in the back out of the view of customers.
3) Refrigerant scale to measure the weight of refrigerant added or recovered - this in conjunction with the 30 Lb'er will be more accurate way of adding refrigerant than by just using the cans.
4) HECAT DIY flush gun to flush components and lines (except compressor)
4a) Possibly looking at a larger air compressor as you find that flushing uses a LOT of air that your measly 20 gallon, 5 cfm psi direct drive POS compressor is working itself pretty hard and you're concerned it won't last very long at that rate.
5) Various tools specific to the vehicles you're working on (service port adapters if working on R12 systems, spring lock coupler tools for working with spring lock
connectors, I'm sure there's more, especially if you're rebuilding compressors)
6) Extra vacuum pump oil
7) One recovery cylinder dedicated to each type of refrigerant you'll be dealing with

If you REALLY get into it, you may start looking at
6) Micron gauge as you realize the resolution on the vacuum portion of the manifold gauge set is fairly poor
7) Tank of nitrogen & regulator to pressurize the system and look for those really slow, but annoying leaks using an.....
8) electronic leak detector
9) An additional recovery cylinder for storing "contaminated" refrigerant (anything other than pure R12 or pure R134a)

...And if you start taking on outside work
9) Refrigerant identifier to ensure you're not dealing with a contaminated refrigerant which would in turn contaminate your tank of recovered refrigerant, which would in turn contaminate every system you worked on afterwards (unless you charge every vehicle with virgin refrigerant)
10) Sealer identifier so you don't mess up your expensive recovery equipment because the $%^! customer or their previous mechanic put sealer in their system thinking it was a cure-all.

Not sure what kind of vehicles you plan on working on, but if you plan to work on R12 systems, you need to get your Section 609 certification (see FAQ section of this site) in order to purchase the refrigerant. No big deal, it only costs about $15, and you take an online quiz. They provide a study guide for it in PDF form (definitely worth reading, but you can search by keyword as well when taking the test, LOL).

I started the DIY route a little over a year ago - I've found I enjoy doing the work thus far. Up until recently, I'd just evacuated and recharged my van. But as we speak, I'm doing my first complete system repair on a friend's '93 mustang. I'm hoping it turns out well. It takes a bit of an investment to get over the hump to the point where you don't have to take it to a shop for parts of the repair process. If you live in a hot climate, it may well be worth it though.

With that said, it can also be an expensive process to find a place (locally) that does good repair work. A couple years ago, the A/C in my truck went out and I had a shop that came recommended to me (from someone who knew nothing about cars unfortunately), and they put Freeze 12 in my 90 Silverado, rather than R12. They also must not have done a very good job flushing the components, as the compressor went out again in a day or two. After they finally got it fixed, it has never cooled as well, but I didn't know any better at the time. I'm planning to flush out the Freeze 12 and put the R12 back in when I get the time.


Edited: Wed July 09, 2008 at 10:57 AM by webbch

bearing01 on Wed July 09, 2008 10:51 AM User is offline

The 3cfm single stage vac pump by Mastercool is great:

The $90 manifold gauge set by Mastercool is also great:

I would advise to go with Mastercool gauge set. Before buying that set above I had a Harborfreight cheap gauge set. If you don't want a disposable tool then go with quality. Otherwise you'll just end up buying a quality set later.

Another tool to consider is a Halogen Leak Detector.

I got an infrared thermometer that I use to measure condenser fin temperature, but if you want to measure superheat or subcooling then best to use a thermocouple. You'd need a multimeter that has a K-type thermocouple input and then get a bead-type thermocouple that you can tape onto the line you want to measure. The wand/stick probe type temperature probes aren't very good because the get confused with air temperature surrounding the think you're trying to find the temperature of.

edvmemphis on Wed July 09, 2008 11:51 AM User is offline

Thanks to both for the inputs. Webbch, a very comprehensive list and it looks like it's in the right order for "growth". I welcome other opinions on what is or isn't useful. I'm sure there are no right answers here, just valuable insight from everyone. Thanks again.

Here is a specific question: A recovery machine has high-low gauges and it has a pump. Are the gauges equivalent to those on a charging gauge set? Can the pump be used to evacuate prior to recharge? I've seen the $4,000 do-it-all machines, but I'm talking about the $300 recovery machines. Can their gauges be used for diagnosis and charge? Will they evacuate prior to charge?


Ed V
Memphis, NY

97windsatr3.8 on Wed July 09, 2008 11:55 AM User is offline

"The $90 manifold gauge set by Mastercool is also great: "

I am interested in this gauge for a while. Before I order it, I have a question:

From the introduction,

"Code: 66773
Price: $89.42
Mastercool "DIY" Special R12/R134a Brass Manifold with 2-1/2" Gauges Auto Shut Off Hoses , Tank Adapter and Couplers Included. ----- True Mastercool gauges not a cheap knock off's as seen on some Internet sites.
I believe it can be used directly on R134a system.

But how about R12? I see it just include one hose set . IF it can work on R134a, how will it work on R12? I mean how it can hook up both R134a and R12 ? Does it include two set adapter coupler and one for R134a and another for R12?

Any one has already bought it and experienced both R134a and R12 with this particular gauge set?


mk378 on Wed July 09, 2008 12:03 PM User is offline

The gauges on a recovery machine show pressure at the inlet (yellow hose from the manifold) and outlet (recovery tank) of the machine. You still also need a gauge manifold to measure system pressures.

With the convertible gauge set you'd take the R-134a couplers off the ends of the hoses and then they will connect to R-12 ports. The same hoses are used for either. An adapter is also used on the yellow hose to connect to tanks of R-134a, which have a different outlet fitting than tanks of R-12.

webbch on Wed July 09, 2008 12:17 PM User is offlineView users profile

Any one has already bought it and experienced both R134a and R12 with this particular gauge set?

Lots of folks here have bought it I'm sure. I'm one of them, and yes you can use it for both. Technically, you could use it for any refrigerant I suspect, because the gauges read out in PSI. Additionally, they have separate scales that correspond to the temperatures of R12 and R134a (which is just the relationship to pressure). But you *could* use them for another refrigerant - you'd just have to infer the temperature of the different refrigerant given the pressure reading in PSI and knowing the pressure-temperature relationship of the different refrigerant.

If you use them for one refrigerant and want to change over to another, just be sure to purge the lines of the old refrigerant. That's the advice I found here AFTER I purchased a second manifold gauge set for use with R12 (was worried about cross contamination). But I find I like having two gauge sets anyway, so no big deal. For people working on lots of systems, they probably prefer to have one gauge set for each refrigerant type to avoid needing to purge the lines when switching between refrigerants I suspect.

Edited: Wed July 09, 2008 at 12:18 PM by webbch

97windsatr3.8 on Wed July 09, 2008 12:24 PM User is offline

Thanks. webbch.

Does it includes TWO set of adapter to hook up R135a and R12 or just universal coupler?

You know R134a and R12 has difference size refill niple.


TRB on Wed July 09, 2008 12:34 PM User is offlineView users profile

The Mastercool 66773 gauge set uses R12 style hoses. The R134a couplers are designed to fit the R12 style hoses.


When considering your next auto A/C purchase, please consider the site that supports you:

Edited: Wed July 09, 2008 at 12:35 PM by TRB

mk378 on Wed July 09, 2008 1:16 PM User is offline

Basically it's an R-12 set that is supplied with 3 adapters to put on the system end of the hoses when working on R-134a systems.

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