HVAC heat pump thermal expansion valve

[ethilo]

Hi all,
We have a hybrid HVAC system with a heat pump for mild weather and natural gas furnace for the very cold season. Since I bought this house the heading comprehend of the heat pump hasn't worked, only AC, so we've been using the gas furnaces for all hearing mess. I had a guy come and tell me the thermal expansion valve is stuck and needs replacing but that may or may not resolve the issue. Just wondering out amongst the group if that is something DIY-able or even serviceable, or if the whole thing should just be replaced. The unit is 12 years old now. Thanks!!!

[Takk]

It's serviceable, not really DIY without refrigerant handling training (laws and stuff involving that).  -- gotta drain all the refrigerant, capture, braze, replace, pull a vacuum, replace refrigerant.

Whole thing could be replaced, if it's older than 15 years (ASHRAE average life expectancy chart - Google as necessary).  He did identify it may not solve the issue, if the issue is controls oriented (is it telling the system to go into heat pump mode? or just turning on that gas furnace?), could be something else I'm missing as well, I'm not a residential expert in these things, just work with HVAC too much.

[ethilo]

When heat pump mode is running, refrigerant line is freezing over when you lol down into the unit and no cooling of the air happens. When you switch it to heat, the line thaws out and it heats the house