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What kind of device do I need to check the refrigerant level in my home AC?

Can I buy something like Mountain MTN8205 R134a Brass Manifold Gauge Set With Couplers?

Please suggest if I am on the wrong path.

  • You need to test for the superheat or subcooling, depending on the type of orifice: piston or TXV (respectively). A pressure test just tells you if it's empty ;) - If you're testing by: "Beer can cold; you're too old." – Mazura Jul 6 '16 at 2:43
  • honestly every HVAC guy i call that's what they are doing, using these gauges and charing me a lot – SeanClt Jul 6 '16 at 2:47
  • If they have a temperature probe and start talking about wetbubs, then pay them ;) HVAC SUPERHEAT explained on a real unit. R-410A analogue gauges – Mazura Jul 6 '16 at 2:49
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    Found one youtube.com/watch?v=BH3eojSDPrc – SeanClt Jul 6 '16 at 3:15
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    Being able to make heads or tails out of this: Superheat and Subcooling: The Best Ways to Ensure Proper Refrigerant Charge is why they get paid the big bucks. - You need a gauge set, temperature probes, the manual from your unit to find the target superheat/subcooling number, and a recovery tank (and a pump), or a can of gas, depending. Or there's no point to any of this. – Mazura Jul 6 '16 at 3:19
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Yes you can buy gauges, but do you know what you are doing? Do you have a 608 small appliance licence?(systems under 5 lb most homes have larger ones and require the high pressure license). Next just having gauges will only give you a ball park, a dual temp gauge (at minimum a good single temp gauge) is needed to understand what the pressures really are. If you do crack your system with that huge hose set now you have just lost some of the charge by checking it. How do you know if it is sealed? the cheap-o freon detectors sound like they do a good job. Last year we fixed a leak that the 25$ detector barely could sense, my D-tek showed me the area but it was so bad the compartment was flooded. A spray bottle with bubble solution pinpointed the leak. The owner put the cap on tight but it still leaked out most of his R22 chilled water system, at 50-100$ a pound + a service call he was lucky it was only a 15 lb system. The last point is there are up to $10,000 rewards for turning someone in for the release of Freon (The EPA collects a fine for the up to $25,000 fine if you get reported releasing Freon). So I will say again yes you can buy gauges and look at the gauges. Using only pressure gauges will not tell you the charge level. (I don't do home service calls but I have friends that do not cheap).

  • Can you provide the model of your d-tek leak sensor ? I am working towards my license – SeanClt Jul 5 '16 at 22:08
  • Also you said spray solution bubble solution like good idea for me, can you please suggest what kind of liquids or solution I need and what kind of bottle ? – SeanClt Jul 5 '16 at 22:10
  • I have 2, more expensive D-tech select can use with head phones in noisy industrial settings rechargeable & Tek-mate cheaper but a very good unit mine is 5-6 years old and still on the original sensor not as sensitive as D-tech. Get your self a set of gauges directly connected to gauges, no hoses. This will save you in the long run if you crack a marginal system almost no loss at all. – Ed Beal Jul 5 '16 at 22:18
  • Can you please provide models links etc ? – SeanClt Jul 5 '16 at 22:19
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    "...but do you know what you are doing?" +1 – Mazura Jul 6 '16 at 2:41
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Sure you can buy gauges, leak sniffers, temperature probes, and a bunch of other gizmos. Unfortunately, it doesn't really make any difference.

The average homeowner doesn't have the knowledge, skill, tools, experience, or certificates required to repair problems with the refrigerant system.

You can determine you have a leak, and even find the exact location of the leak. But unless you have everything required to fix the leak (not likely), you're still going to have to call a professional to fix the leak and charge the system.


When you do hire a "professional", if they tell you they put in x lbs of refrigerant, ask them if they fixed the leak. If they say no, don't pay them until they find and fix the leak.

Refrigerant systems are closed loops, and don't lose refrigerant unless there's a leak. If you just keep dumping in refrigerant, it will just keep leaking out.

  • This is valuable recommendation. A tech came out a few years back says freon is low, puts more freon in system, and then tells me there's a leak, but did not fix it. A week later, compressor overheated, freon continues to leak, and needed a new replacement unit! Wish I had known this back then. – KJYe.Name May 24 at 18:15

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