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Both of the Haynes manuals for my cars list refilling the refrigerant in your car as a do it yourself procedure. Both vehicles use R-134a refrigerant and the manual shows them being recharged with a simple hose without a pressure gauge on it.

I also watched the ChrisFix video on recharging your A/C refrigerant, which makes it look simple, safe and easy. The product he uses in the video comes with a pressure gauge and contains sealant.

However, when I started reading the many one star reviews, things didn't look so simple or safe. Many people destroyed their compressors, by either overfilling or by the sealant clogging their compressors.

Quoting one reviewer:

I have spoken to a couple of different shops and both have said they see person after person come in with issues from these home kits. They don't show the amount that goes in, just the pressure in the system. Well that isn't nearly enough information since the weight is what is important.

and another one:

Don't use this unless you have professional gauges. You can likely borrow them (appropriate gauges) from Auto Zone or equivalent. Or, just do what I eventually did, take it to Jiffy Lube (or equivalent) and let them remove all the refrigerant and refill to factory specs.

My question is not about this specific product, I'm just using it and the reviews as an example.

  1. What issues can I run into trying to recharge my A/C refrigerant myself?
  2. What equipment do I need to do it safely ( for me and the A/C system) ?
  3. What issues are there with sealants?
  4. Should I get a refill that contains compressor oil?
  5. Would I be better off just paying a shop to do it?
Community
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Robert S. Barnes
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    Good answers below, but I want to reiterate that overfilling the compressor is very bad, and very easy to do with the DIY cans they sell. Also, some cars are more finicky about it than others. If you do take it to a shop, make sure they are doing it the right way (full vac, measure, and refill) rather than doing a cheap "spray a little more freon in there" job. It's A/C season, and there are some shops that try to make a quick buck (I know, imagine that...). – JPhi1618 May 03 '16 at 14:42
  • I want to add, but it's not an answer. Refrigerant and oil should NEVER EVER need refilling or topping off. If it does it's because there is a leak. Part of fixing the leak is refilling the system. Most shops will evacuate the system and refill if after any leak repair. It's pretty simple for them, very hard for you. – coteyr May 03 '16 at 20:13

2 Answers2

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What issues can I run into trying to recharge my A/C refrigerant myself?

The most common DIY problem is overfilling oil, under or overcharging refrigerant and installing the virus that are sealants.

What equipment do I need to do it safely?

Gloves and safety glasses. The PAG oil used is not good for humans and the gas can cause frostbite.

What issues are there with sealants?

Sealants rarely work well if at all. They can plug critical parts such as expansion devices or heat exchangers.

Should I get a refill that contains compressor oil?

No, the oil amount is set during build and it impossible to know how much is might have been lost. Overfilling reduces system performance and under filling will destroy the compressor.

Would I be better off just paying a shop to do it?

Yes

There are two key issues that make this a non-DIY job. A high vacuum must be pulled on the system to ensure that every last bit of air is out. And the refrigerant must be carefully weighed during installation. A few ounces over or under can significantly affect system performance. The DIY install systems only show one of the available pressure readings and in any case charge amount cannot be determined from pressure readings.

Fred Wilson
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    So you're saying that the only reliable way to do this is to dump out all the old refrigerant and re-fill with a known measured amount like what's done in a shop? Why do the Haynes manuals and so many others present this as a simple DIY job? – Robert S. Barnes May 03 '16 at 08:09
  • Also, when I asked about safely, I was actually intending "safe for the A/C system", but I appreciate the personal safety points also. – Robert S. Barnes May 03 '16 at 08:11
  • Concerning the oil. Your answer leads one to believe that there is no solution to address the possibility of lost oil when there is a refrigerant leak or if you have to open the system for repair. – user288719 May 03 '16 at 15:00
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    Robert, I cannot speak for Haynes as to why they say this is a DIY job. Perhaps their audience demands it. On the subject of a correct fill amount, yes, the only way to arrive a proper refrigerant weight is the "weigh on fill" method. The refrigerant is not vented to the atmosphere, it is truly a "greenhouse gas". It is recycled and reused, in most cases. – Fred Wilson May 03 '16 at 15:15
  • @user288719 The only true solution to the oil amount problem is to flush all the oil out of the whole system and the fill with the measured amount of the correct oil. A time consuming, expensive task that is only done when absolutely required. – Fred Wilson May 03 '16 at 15:19
  • @Fred Wilson. Thank you for your reply and based on that information it leads one to believe that there is in fact a margin for error in the manufacturers stated oil capacity requirements. Of course the problem lies in the fact that we have no idea what the margin is. – user288719 May 03 '16 at 16:11
  • "charge amount cannot be determined from pressure readings" - Can you please clarify? If I recall my basic chemistry correctly, PV = nRT ( * = * * ). So in theory if you know the temperature and the pressure, and can estimate the volume of the refrigeration system to a reasonable level of accuracy (or perhaps the specs will explicitly list this), you can solve for 'n', which can then be used to determine the mass of refrigerant currently present in the system. – aroth May 04 '16 at 04:02
  • ...or, if you know the mass of refrigerant you want to end up with, you can work out the desired value of 'n', sub that in with your temperature and volume values, and work out the target pressure for your particular system. In theory, at least. – aroth May 04 '16 at 04:04
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    @aroth The ideal gas law does not work here because the refrigerant is in three states in an operating A/C system. Low pressure gas. High pressure gas and high pressure liquid. – Fred Wilson May 04 '16 at 04:31
  • @FredWilson I really appreciate your answer and comments from 4y ago. My 2010 Toyota RAV4's air conditioning / climate control isn't blowing cold air anymore. It blows air, but it's just not cold. I hear no concerning noises of anything broken, so probably its refrigerant has leaked. I bet it's totally empty.

    A lot of people recommend do-it-yourself kits like this $33 can from Walmart (https://www.walmart.com/ip/A-C-Pro-Ultra-Synthetic-R-134a-Refrigerant-Recharge-Kit-20-OZ/353326131) ...

     – Ryan Sep 13 '20 at 18:16
  • ... and I even found a great video tutorial for my model RAV4: https://www.carcarekiosk.com/video/2010_Toyota_RAV4_Limited_3.5L_V6/air_conditioner/recharge_freon

    @FredWilson I'm wondering why you've said sealants are a "virus". And whether 4y later you still discourage the DIY approach recommended by these kits and these tutorials. If you can elaborate at all, I'd really appreciate it!

     – Ryan Sep 13 '20 at 18:16
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Personally, I recommend option #5.Refrigerant will cause frostbite in sufficient quantity. If you are unfamiliar with the principles of A/c you could damage the compressor. If you accidentally inhale you can be poisoned by it. You have to know which line to charge the system the vapor line or liquid line . If you do not know -Do not attempt it.

Refrigerant poisoning happens when someone is exposed to the chemicals used to cool appliances. Refrigerant is a tasteless, mostly odorless gas. When it is deeply inhaled, it can cut off vital oxygen to your cells and lungs.

Limited exposure — for example, a spill on your skin or breathing near an open container — is only mildly harmful. However, you should try to avoid all contact with these types of chemicals. Even small amounts can cause symptoms.

Inhaling these fumes on purpose to “get high” can be very dangerous. It can be fatal even the very first time you do it. Regularly inhaling high concentrations of refrigerant can cause issues such as:

breathing problems
fluid buildup in the lungs
organ damage
sudden death

Go Option #5

Old_Fossil
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