coil and lines freezing

[paulweath]

I purchased a new Trane XLi14 seer heat pump system with variable speed handler in OCT 2004 to replace my 16 year old system "old faithful". This summer ,when set to cool mode the system, I noticed a freezing/frosting on the line going into the handler. After 4 weeks, about 10 visits from a senior tech, a replaced TXV valve and coil the system still frosts at a thermostat setting of "75 degrees". I this normal for a high efficiency unit that the company promises a comfort level never expierenced? I have a tech coming out this afternoon to look at the problem again. (thank goodness for the 10 year warranty) any insights from anyone would be apprteciated thanks.

[Toolpusher]

No it's not normal,

A few things that cause this are,
fautly txv,
low charge,
lack of or low air flow across the indoor coil,
dirty filter,
running unit during cool weather,txv helps in this condition.
System over sized,for ductwork. and or house.

[Jultzya]

No it's not normal.

And whether it has a 10 year warranty or not (10 calls) is ridiculous!

[smokin68]

10 visits from a senior tech? Time to send out the rookie then for a better diagnosis.This problem shouldn't be hard to solve.

[docholiday]

It's indicating a low load of some sort, either low airflow or a starved coil or cold return air (bypassing some supply).

You are saying the large line if freezing right? If its the small one, there is a kink or restriction in the liquid line unless the frosting starts at the outlet of the TXV.

[Mr Bill]

Man what is the deal we have had so much negitive feedback on all this new super high efficient stuff here lately got to be the installation it could not possibly be the equipment.

Give me an old 9 seer system and I am good to go.

[docholiday]

Sorry Bill but it really comes from installers trying to use the same charging, installation, and troubleshooting techniqes from the older systems. The new ones simply work differently and for those who keep up with the changes they just dont see the problems.

As a for instance. On a 8 seer , beer can cold worked ok,
On a 10 Seer, it didnt work very well but you got by.
On a 12 SEER it is a mess because theres a txv in most cases. On a 14 SEER, you just plain killed a unit.

On a 8 seer, the unit had a puny coil, airflow was simply not as critical, the cap tubes prevented some floodback. On a 10 SEER, the airflow affected how you charged it. On a 12 SEER, you will begin to kill the capacity of the indoor coil by slowing the refrigerant down. On a 14 SEER unit, you just plain kill a unit if you dont provide proper air flow. Motors are now more closely sized to operate at a lower static for efficiency's sake, unfortunaltely the static didnt change bacuase the duct was never addressed.

[Mr Bill]

Doc that was a very good explanation.
Thanks Bill