It's an R-22

I would be suspect of a tech who is recommending to replace an 11 year old system because the refrigerant is low. What was the outside temperature when the tech was at your house? If it was below 50 degrees, then the AC should not have been turned on and the refrigerant levels were probably not checked.

If you trust this company, then get a quote as to how much it will cost to repair the outside leak and add the refrigerant. Also ask how much refrigerant needs to be added. If you don't get straight answers get a second opinion. You should not be adding refrigerant without repairing the source of the leak.

You can install a brand new system, but in my opinion you will get very little of it back on the sale of the house. I would recommend a repair from a reputable HVAC contractor if it is needed.

Get a second opinion.

Yes, there are HVAC companies who will use any possible situation as an excuse to say you need to replace your equipment. Adding coolant is the HVAC equivalent of "take two aspirin and call me in the morning, I don't know what the problem is". If there's a leak, it should be found and possibly fixed. This is a symptom of an incomplete or wrong diagnosis.

If you're selling the house, repair (replace) the leaking component, don't replace the entire system. Repairing will be less than 1/2 the price of replacing.

A confirmed leak must be repaired, else the added refrigerant will leak out again. I couldn't in good conscious sell a house with a confirmed HVAC problem that isn't repaired.

If you're in the process of selling the home, it is not likely you will get any increase in the selling price of the home, except maybe for very high end systems with a multitude of bells and whistles --- even then you will only get what someone is willing to pay and this amount is likely to come no where close to what it cost you to purchase the new system.

If the AC has problems reaching adequate temp drop across indoor coil this will probably get flagged via a home inspection. However, it's also very likely it may not get flagged. It depends greatly on the severity of the leak, if there truly is a leak. AC tune ups are often times methods used to get in your front door to sell you something, that typically you don't need.

This is why you should have a reputable AC repair guy on speed dial. You will always need one regardless of whether the AC system is new or old.

Because of the age of your system, it's possible it may have a leak. But it's also possible that this leak *may* not require but a recharge and a thorough examination in tightening various refrigerant connections. There are a lot of grey areas when it comes to refrigerant leaks. If you didn't pay for a Freon leak check, I would seriously question the validity of any such claim.

Especially if you haven't noticed any cooling problems.

Why wouldn't you accept a free Freon leak check? Because then the company doing it only has the incentive of finding a leak to sell you something. [That you likely don't need.] But free sounds so good.

Temp drop should be 15-20 degrees. I prefer to see closer to 20 degrees.

If a home buyer is more concerned about the mechanicals of the home a new system may help you sell the home faster in that situation.

Air conditioning and Heating are typically viewed as a needed accessory by anyone looking to purchase a home. So while you don't typically get a higher value for the home for having a new system, the home price can be effected when part or parts of that system have problems and are requiring a repair.

If the home is located in a more extreme cooling climate the amount of time it takes to sell the home could be impacted, but only if the cooling performance is noticed while viewing the property.

Cooling performance can be effected by design of the system, just as much or more than Freon leak related issues.

I service the Katy, Cypress & Richmond, Texas areas.