After about a year from re-charging my A/C with R-12, I'm finally going to wrap the pipes at the expansion valve.

My question is what does the little copper tubing from the expansion valve do and how should I, if at all attempt to wrap it?

Thanks in advance,

Matt

Hi Matt,

The capillary tube with the end wrapped in a coil is the thermal control for the expansion valve. The end must be in good thermal contact with the evaporator outlet at the side of the pipe as Phil says, to be where the refrigerant flows. The drawing in the conversion kit shows it attached right at the crotch of the tee fitting where the equalizer tube connects (the other small tube).

The instructions simply say "Insulate the evaporator pipes and screwed joints. Install the cover. Note! Do not Insulate the expansion valve."

Perhaps Phil can tell you why they recommend against insulating the expansion valve. My thoughts are it would slow down the feedback at the diaphragm. However if I found it dripping condensate on my passenger's ankle, it would get some insulation.
--
Art Benstein near Baltimore

A woman came home, screeching her car into the driveway, and ran into the house. She slammed the door and shouted at the top of her lungs, 'Honey, pack your bags. I won the lottery!'
The husband said, 'Oh my God! What should I pack, beach stuff or mountain stuff?' 'Doesn't matter,' she said. 'Just get out.'

Hi Art,

Long time no type. Hope your Bricks are running well.

Any chance you can shoot me a pdf or post here the drawing to which you are referring to? I'm very visual and I believe I understand exactly what you are talking about, but a picture would really help.

Thanks!

Matt

If you can go to a refrigeration supply house and buy closed cell foam wrap on a roll. It has a peel and stick adhesive that allow you to do a nice sealing job that is compact and efficient. You will have plenty left over for other projects. You do not want to see any of the valve or any tubes from it uncovered as they will sweat and drip on your tootsies or carpet.

As far as the copper tubes go, the one that goes to the very top of the round hat affair is what operates the power head and is the most important. It controls the actually output of the liquefied (condensed) refrigerant from the high side according to the sensing bulb on the end of that copper tube. If there is another tube emitting from the center of the valve body it is only a pressure equalizer. It helps the power head respond better to the evaporator coil and the TXV's distribution system.

You also want that sensing bulb or tip wrapped up and it must be tightly clamped onto it that tube. The bulb needs to be on a SIDE of and not on the bottom of tailpipe or return line to the compressor. A four or eight O'clock position works so you sense for only vaporized refrigerant and not any heavier oil droplets traveling along the bottom.

On vertical lines, this does not come into play but you want the farthest end of the sensing bulb pointing downwards so its own refrigerant inside the bulb collects at the bottom. Liquid refrigerant will migrate or collect at a coldest point. This will then boil off correctly back up tube towards the power head. There is a diaphragm inside there and it is more partial to having only gas operate it due to its surface area for good mechanical response.

The proper location of that sensing bulb, up or down the return line, will affect the systems performance along with insulation and I wish you could have done it before now.

Phil

Phil,

Just got your email.

I think I understand what you are saying, but I'm not sure so I've attached a picture of how mine is set up for you to look at. You say the following:

"You also want that sensing bulb or tip wrapped up and it must be tightly clamped onto it that tube. The bulb needs to be on a SIDE of and not on the bottom of tailpipe or return line to the compressor. A four or eight O'clock position works so you sense for only vaporized refrigerant and not any heavier oil droplets traveling along the bottom."

So I want all of the sensing bulb wrapped up, even the head unit, or not the head unit? When you say tightly clamped to that tube, do you mean the sensing tube needs to be wrapped tightly to side of the expansion valve?

Do I need to wrap pressure equalizer tube as well? If so does it matter where I wrap it to?

Please advise when you get chance.

Thanks in advance,

Matt