What is this?

What is the copper wire for at this evaporator coil? It was all wrapped up with tape.

I think it might be a refrigerant return line. Should be warm to the touch. I could be wrong on this but believe I am right. I’ll be looking for someone else to reply to either back me up or educate me as well.

Is it as wire or a capillary tube for a control thermostat??
Expansion Valve.jpg

A thermostatic expansion valve ( TXV) is precision device used to meter the flow of liquid refrigerant entering the evaporator at a rate that matches the amount of refrigerant being boiled off in the evaporator, This is it’s main purpose but like all the other metering devices it also provides a pressure drop in the system, separating the high pressure side of the system from the low pressure side. thus allowing low pressure refrigerant to absorb heat onto it’s self.

More info at:


Thanks for the replies. Micheal I believe you are right. First time to see one of these. :smiley: Good link. Thanks.

It looks like there might be a mold problem threr also

Michael Is Right. For may years, these were installed inside the cased coil. Carrier, Lennox and a few others are now putting them outside.

Mold problem? What is the problem? That is mildew from being wet and cold all the time.