Continuous AC problems with several units

[Frank Houng]

Hi Folks:

I invested a 14 unit townhome in Dallas area end of 2013.   The subject property was built in 2007, so I imagine the AC are about 7 years old (warranty was for 5 years)

Since I bought the units, we have continuous report of AC problem in different units,  most of them seem to be pointing to the same issue:   Coil rusted and leaking.   We ended up replacing the coils on each of the cases.  6 cases so far,  costing $ 1955 each time (to replace 3 ton coil, refill freon, and labor.

Since I live in California, and these investments units are in TX,   I'm not sure if it's wrong to judge these repairs based on my experience from California.   But normally I do expect AC to last longer, 10 to 15 years.   And statistically 6 units out of 14 is a rather high percentage.     My impression is that there could be maintenance issues that my property manager may need to teach or talk to the tenants.  Or perhaps if it's not maintenance problem,  then we could be looking at similar issues with the other 8 units very soon.   If that's the case,  would it not make more sense to take preemptive action and have someone check them out?   This way, if we discover similar problems,  at least we can negotiate a discount for 8 units, rather than pay for each unit as they come along.

By the way,  these AC are Byant model: FA4CNF036

Thank you for your valuable opinion and advise in advance.