[Shelby]

I found this site using a search and found you guys the most knowledgeable.

I had 2 units installed 3 years ago by a local firm (that unfortunately had to close it's doors). I reached out to a another local A/C company that is listed on Mitsubishi's website as a Diamond contractor. This started back in October of this year. One unit is secured to concrete (no problems at all) and the other is suspended from a wall using manufacturer brackets.

Tech1: He was a nice guy, didn't really know the unit all that well and was trying to service it at the head unit. He then called another tech who told him to simply add refrigerant and call it a day. I watched this tech the entire time. Using his gauges, he then proceeded to put refrigerant in the unit. At one point he purged some of the refrigerant as he had put too much in. He left and wasn't confident that this resolved the issue. The unit ran for 3 days making all kinds of noises and never cooled so I turned it off and contacted the company again.

Tech2: Again, really nice guy. He began to use a spray to test the connections on the outdoor unit and found one connection loose. He tightened the connection, used a scale and gauges to put bring the refrigerant to a proper level. He then had me set the temps low (outdoor temp was 95) and verified the unit was cooling properly. He left and I had to pay for his visit. I quickly had the office remove the first charge.

Tech3: This tech was the one most familiar and was the one responsible for training the other techs (yes, I know). He checks all the connections and found the connections at the head unit loose as well. He tightened all the connections and performed the same process as tech #2. He then indicated that he would return 1 week later to check the levels and to call if I noticed any problems.

I called and delayed his return as things were working fine. Then in mid December we had temps drop into the teens. This is when I noticed the heat stopped working. So I called back and Tech#3 returned with another tech (in training).

Diagnosis: Tech 3 verified all the connections on the outside of the unit were to spec. I didn't watch what they were doing this time but they asked to come into the house so they could check the head unit. They used a tool and identified the leak coming from the evap coil (think that's what they called it). They showed me and I could see oil on the aluminum fins. They took photos of the unit (leak) and the serial number and indicated that the office would call me about a replacement coil (?) or possibly a replacement head (if they could find one; Mitsubishi GE09-NA). They also asked who initially installed the unit (I gave them the name of the firm).

(many apologies for the long story)

So is it possible that:
[1] Tech #1 over pressurized the system initially causing the failure.
[2] The unit just failed after 3 years of service.
[3] A combination of #1 and 2.

Thoughts?

Much appreciated...
-- Shelby