Getting Started with AC Repairs

[seanb02]

Hey folks, as the title mentions I am interested in getting into doing my own AC repairs on the trucks and tractors around the farm. Lets start off with a budget of say $1,000. Seems to start with I would need a gauge and manifold set with hoses, a vacuum pump, and a separate (digital?) gauge to measure the vacuum pulled down by the pump. I've been researching primarily Mastercool and Robinair brands. Yellow Jacket appears to be another good brand, but would likely put myself out of budget. There are so many different options out there is is getting a little confusing, such as single stage or dual stage for the pump, and how many CFM's it needs to be. 2 way or 4 way manifolds, hose length, etc.

Then I came across this (link below), looks like kind of a neat all in one kit approach without having to jump up into the $3,000+ recovery machines. Anybody have any experience with something like this? Or if I could do better in piecing my own kit together from separate components, maybe you folks could point me in the right direction. Until I start to use the tools and gain some hands on experience it is rather confusing. Thanks.

https://www.tooltopia.com/Mastercool-MAS91585B?page=1

 

[metaldad]

for the price, with that setup you'll be fine.

 

[Zewnten]

Basically what I pieces together for my needs, just add an empty bottle. Dont forget your little card when you do it, so you can buy refrigerant and avoid fines (you probably already know this though)

 

[signcrafter]

That "all in one" unit is just a fancy metal stand with a vacuum pump and set of gauges and a scale. I guess it could be nice to have and roll around to cars. But what it doesnt do is recover the old stuff. That's what the 3000 dollar and up units do.

I got started by fixing my own leaky system so it was already drained. So I bought a set of gauges and pump. Got it close enough for my own stuff at that time. Then I bought a scale, flushing kit, leak dye kit, sniffer, and a bunch of other stuff. The one thing I still cant do is recover old refrigerant. That is next on my list and will probably get one this spring as soon as people start asking me to fix their ACs.

And like mentioned, take the online course and get certified for ac work so you can buy 30 pound tanks. The test is open book and it's pretty much common sense stuff.

 

[Wrench97]

You can't buy a 30lb bottle of 134a without a license but you can buy the 12oz cans.
Don't go over board get a set of Mastercool gauges> https://www.amazon.com/dp/B000BHKZIE/?tag=atomicindus08-20 a single stage Robinaire pump > https://www.amazon.com/dp/B005CO9GX6/?tag=atomicindus08-20 and a Robinaire scale> https://www.amazon.com/dp/B000JFNAMQ/?tag=atomicindus08-20.
Leaks can be found by looking for the oil spot, using soap and water spray or by putting pag oil dye in the system and using a LED light.
Newer stuff will have R1234 YF and need another set of gauges / hoses/ of their own.

 

[a_whale]

I wouldn't go for a recovery machine unless I was running a business. For me, the only reason I would need to do recovery is because of a major repair which *required* disconnecting(breaking) the A/C system lines but even with full drivetrain work I almost always find a way around this. Sometimes it's inconvenient to have the condenser hanging in the way but a few bungee cords do wonders. I use a digital scale, manifold guages, and thermocouples.

As others have said you need the cert to buy large cylinders but the EPA test is easy, I'd just go get it, you can find info you need to pass it online and you get a way better price with the cylinders, I would consider this a must if you are servicing an entire farm. You can often find the cylinders on craigslist or facebook marketplace but I wouldn't count on that always being available.

One thing I would definitely get is a dual thermocouple meter, you can get nice ones used on eBay or buy a cheaper new one. Most cars/trucks should have pressure/temperature vs. charge level in the service manual HVAC section and this will allow you to calculate how much to add if you have an undercharged system. Way easier than recovery and full recharge. If the tractor doesn't have this info you can guesstimate it by knowing refrigerant capacity of the system.

Also you mention needing a vacuum guage but my guages read vacuum so you shouldn't need a separate guage when you are pulling a vacuum on the system.

 

[a_whale]

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[theoldwizard1]

Longer hoses. At least 6'

Not sure where to buy them but a kit full of spare A/C O-rings will be valuable. Leaks can hard to find.

 

[a_whale]

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[seagull369]

The gauges on just about any manifold gauge set already read vacuum, so getting a seperate set to read that isn't really necessary. If you use a charge hose that has built in valve on the end, you won't lose any vacuum in the line when doing the switch over from vacuum to filling. I'm no pro, but I view digital gauges as "flair" and not necessary. Mastercool is a good brand and replacement parts for the manifold sets at least seem to be readily available. Long enough hoses can certainly be important. You want your manifold to be able to hang on the open hood there and have the hoses comfortably reach the service ports wherever they may located under there. I don't know anything about single or dual stage vac pumps nor the cfms, but unless you're in a rush, even a basic model pump should do the job. You just need it to pull the 29 inches or so (which will happen quickly) and continue to run for about an addl 30 mins to boil off any moisture.

You'll want to get an electronic leak detector with easy to replace tips. Black light with yellow glasses for dye detection. Instead of a dye injection tool, I just use cans with dye already in it, which are about as cheap as the cans without. Takes the worry out of wondering if I put too much dye in or not enough. A reclaiming machine will probably be one of the biggest expense in your whole setup. If you're doing this professionally, invest in a kits that detect for the presence of leak stoppers and other refrigerants that may be in the system that aren't supposed to be. You want to steer clear of any vehicles that have either of those issues.

Some people like to pressure test for leaks using nitrogen, so you'd need a bottle, regulator, a hose and fittings. Others use compressed air, but it's a bad idea unless you have a good refrigerated air dryer in your
setup.

 

[monkeyspanners]

If you're on a budget you can make a basic recovery machine from a second hand domestic fridge compressor, pick one rated for R134a.

 

[joshmodelskidoo]

I got a hf special gage set and electric pump and use the small cans. Paid $1000 to get her rear ac fixed on her traverse so I figured it was time to give it a try. Worked good last summer on her old equinox. If you don’t want to go the harbor freight way napa has there real deals and the other auto parts stores have an option to have a professional account. Having a farm maybe you already have an account and you can ask them whats on sale. I go through oriley auto parts and you don’t need anything special. I just work on my family’s vehicles and they asked me why I don’t sighn up. I figured I needed a business and tax id but I didn’t

 

[charbar]

Half of the 'farm' type work seems like its just topping off or charging an empty system. A decent set of gauges, vacuum pump, and a scale with probably cover 90% of what you are wanting to do. If its something you need to evacuate, there is always someone local that can do that for you. Leaks can be tricky, but if you're just doing it for your own benefit, then a good eye and some soap and water can find most leaks.
A flush gun would be a good investment as well, for when a compressor implodes or desiccant bag lets go. The canister type ones with a short air hose and nozzle are cheap.

Mastercool and RobinAir are top notch brands in my opinion, so you're looking the right direction.

Its been so many years since I got my a/c 'certification' card that I dont even recall what it takes, but it's worth looking into. Or find a buddy that will sell you one of his drums. 30 lb. drums are the only way to go. The small cans you get at the auto parts store are a joke unless you have all day to d!ck around with them and just want to guess how much freon you have in the system. You'll never get all 12 oz out of that 12 oz can. How much do you get out of them? Who knows, its a guess.

As said, dont forget a good O-ring kit and PAG oil. Keep some PAG 46, 100, and 150 on hand and you should be covered. I buy the stuff with the dye already in it. For a home shop type deal like you are talking, 8ish oz. of each oil and a gallon of flush should be enough to keep on hand for any 'emergency situation' until you can get to a parts store. Some ag stuff will take more though. Just did a 4960 Deere for a customer and it took 11 oz with the Denso compressor.

Buy yourself a book also and do some reading.. If you've never done any A/C work, you're going to be in for a surprise if you just hook up a set of gauges and dive in.

 

[CHRIII]

You might want to get a couple of spare schrader valve cores. I leaked almost $1000 worth of R12 from my heat pump when one didn't completely close after a seasonal maintenance!

 

[Milton Shaw]

The micron vacuum gauges read a much better vacuum than a manifold set. Most gauge sets read 30 inches of vacuum as they are off as 29.?? is the best total vacuum you can reach. A micron gauge reads to 0 microns which is not reachable in automotive repair. Normally a 500 micron reading is about the most you can get if ideal conditions and new vacuum pump oil is used. Moisture is the reason for using micron gauge as moisture removal starts after 29 inches of vacuum for the most part. At 500 microns you have 99.99 percent of the moisture out of the system. At manifold gauge setting of 30 you have just about 0 percent out. Moisture ruins the system and keeps it from operating right. I now am a firm believer in micron gauges for moisture control, but if you are replacing the receiver/dryer you have just caught most of the free moisture when the system starts. I did refrigeration repair for 20 years and replaced 2000 or more compressors. By company policy we never used a vacuum pump or even a manifold gauges set. Each system got a new pickle dryer (size of thumb) that would capture more than 100 drops of water. I don't know capacity of car dryers but they are 20 times the size of what we were using so they could probably hand a cup of water before it started causing problems. Unless you can get a micron gauge cheap don't worry about it.

 

[Wrench97]

For automotive you don't need a micron gauge or a pump with the ability to get there.

Old timers use to "sweep" the system(put Freon in one side and let it escape out the other)and never pull a vacuum.