Heating Help

Txv

Recently at the shopping center I work at, I had a couple of txv's that i believe are malfuntioning.  They are non bleed txv's, and are passing absolutely no refrigerant through the valve. I hate to make a diagnosis based on supposition and guessing.  Is this a normal failure or am I not understanding how these things work?  Is there maybe something else i can look at? It seems like no matter how mucgh refrigerant I put into this thing, the compressor always pulls the suction side into a vaccuum. Thanks for your help!!!

TXV

Could be! What size TXV are these? It might be the Power Assembly. Turn the superheat stem all the way out,and it might bleed some freon thru. Wrap a hot towel around the TXV thermal bulb and you might get some freon to leak thru.

More numbers.

If it's pulling into a vacuum, I'd suspect a total restriction, in either the TXV or a filter/drier.

txv

Ok, so I wrapped a hot towel around the txv bulb and got nothing.  I had to back the superheat stem almost all the way out before I got any bleed through, but there was charge coming out of the stem.  I'm going to go with a bad diaphragm in the txv.  Or possibly a pinhole leak in the bulb cap tube.  Either way, I'm going to replace the txv.

TXV

It's not supposed to leak thru the superheat stem packing/seal.What size TXV /system ?

txv

Its just a 2ton unit.  Not sure about the size of the txv. 

Typical

Common failure on a little TXV. Probalby not adjustable. Have to replace it. Hopefully it is a bolt on!

Opening pressure on the TXV

There are three pressure that control the operation of the TXV: The bulb pressure, the spring pressure and the evaporator pressure.

If the valve is closed and not passing any refrigerant, than there is no opening pressure, indicating that the charge in the thermal bulb (powerhead assembly) has been lost.

Pretty much an open-and-shut (no pun intended) case.

Good luck!

txv

Thanks Eugene.  It's funnny that you mention that, when I went to replace the txv, I noticed that there was a spot on the cap tube for the bulb that had been rubbing on a refrigerant line that had rubbed all the way through. Thanks everyone for all your input.  I think this is a sight I will use in the future for help when i get stumped.