Automotive Air Conditioning Information Forum

bohica2xo wrote:There it is. The TXV is passing just enough liquid to make the evaporator inlet cold...

If the suction line to the POA is not cold & dripping, the evaporator is starving for refrigerant. The POA is holding 29psi, but I suspect the compressor side of the POA is in vacuum.

Time to recover & bench test that TXV.

I am on my third TXV...the original one, a new one & another used one...what is the procedure for testing the txv?...also is it possible that the drier is a faulty new one?...if the drier is partially plugged, would the symptoms be the same?

It would take a pretty badly plugged dryer to restrict refrigerant that badly.

Some dryers can be put in backwards - this will cause all of the refrigerant liquid to stack up in the dryer. Usually obvious because the dryer gets cold, and the line to the TXV does too.

Where ever the restriction is, expansion takes place - and it gets cold.

A TXV should be wide open at room temperature. With the sensing bulb in a thermos filled with ice & water it should close noticeably.

What does the sight glass look like with the system running?

Before you break the system down again, run it & see where the cold happens.

Filled system with 4 pounds of R12...line from dryer is cold...dryer fittings look like they are different sizes so cannot be put in backwards...verified that end of dryer stamped "IN" is coming from the condenser...sight glass looks foamy...I am thinking restricted dryer?

With an R-12 system, steady foaming and bubbling in the sight glass suggest that it's still a bit low on refrigerant. A full charge typically shows a mostly clear sight glass.

Jesse is the dryer cold at some point?

Because any liquid line restriction acts as an expansion device

Run your had over the outside of it starting at the inlet line and work your way to the TXV. It should all be close to the same temperature.

For example a receiver with a clogged inlet will have a 140f inlet line from the condenser, but the body may only be 85f from engine heat.

Line entering the dryer is hot as one would expect...the dryer body is slightly cool near its bottom...the line leaving the dryer is MUCH cooler (at least 25 degrees cooler) and this same temperature extends all of the way to the TXV.

Restricted right at the end of the dip tube. Hence the foam in the sight glass. Bad dryer it is.

Dryer on order...will install in a few days.

A wheel type pipe cutter will pop that dryer can in half with no fuss if you want to see what went wrong with the old one. Cut the bottom 2 inches off for fun...

Bad dryer it was...now I have to locate a small leak...suspect that it is the original evaporator leaking in the case...fluorescent dye is gathering around the evap inlet edge of the case ...many thanks for the help!