I have not had a txv on a new unit bad from the factory but it is possible. When they installed the new unit outside did they replace the inside unit or line set? Did they flow nitrogen through the lines while they were brazing?

Yes, They replaced the entire Inside coil unit, the Furnace and the outside coil unit. Along with new Line set. (I had a Heatpump with dual fuel XR15 intalled With XV95)

Not sure if flowed Nitrogen during brazing but I'd assume so.

They just replaced the TXV about 1/2 hr ago and still only 15 deg delta between indoor ambient and duct temp (air closest to the coil supply). Used to get 22-23 delta on the older unit taken out.

Will have to wait and see if the outdoor coil fan stops starting up again after a few hours leaving me where we started.

Asked if the Check valve or Dryer filter or if the unit could be over charged and was told no to all 3.

Not sure what else they can check. But definitely not as cool as used to be with the older unit that had leaked from the indoor coil set.

Well 15 degree difference is below standard - sounds like it could be low on charge. Once it stops is it then when it will not restart? If so it might just need a start kit installed. Not all TXV equlize pressures and make it hard to start thus needing a start kit.

Update:

Replaced TXV valve. After 30 minutes, system started to cool to a 20 deg delta and then all of a sudden, stopped cooling again.

Outside unit tries to start and won't.

Tech came back and said Bad TXV again.

To keep the unit going (but at not so great cooling) he took a bulb of some kind from the inside coil and places it on the Lineset before the lineset enters the coil case under the house. . That seems to keep the outside coil/fan running ok and starting up without problems. He double checked the pressure readings making sure not over charged.

Heading towards a different but 3rd TXV valve. He mentioned I have a 2 Ton HP unit with a 3 Ton inside coil which should be ok. So they will try a 2 Ton TXV valve instead of the 3 Ton one.

Troys,

Beginning to see how this TXV works. Seems the tech is forcing the TXV valve to stay wide open by attaching the temp sensing bulb to the hot pipe in the line set. Keeping the TXV fully open instead of shutting tight. Seems that would reduce the pressure seen by the compressor and allows the Compressor to start up without issues.

So either the TXV is closing too much and causing this issue, or the compressor can't handle the different size coil set (Trane said it is a certified combination)
XR15 4TWR5024E1 HP (2 Ton)
XV95 Furnance 60KBTU
4TXCB036BC3HCA coil (3 Ton with 3 ton TXV)

Wouldn't these new units be able to handle the higher pressure already (does the XR15 already come with the ability to handle the hard starts?)

I did ask about the Hard start kit with the tech, but he kinda brushed it aside as not being a possible issue with this setup. Wondering if I should push to get one installed or continue to replace TXVs

Most TXV's go from 2-3 and 3.5-5 ton, I have never installed one that is matched excatly with the tonnage of the unit. Most new units do come with a hard start kit from the factory due to the higher pressure during start up. If it does not have one I would request one be put on. The way they have it hooked up on the liquid line will work but when it is over 90-95 degrees it will not cool very well.

thanks. Yes if the next TXV valve still has the same issue, I think I'm going to be pushing for a replacement coil and condenser HP set. Might ask for a smaller coil set to match that 2 Ton HP unit. I haven't paid the installers yet since we haven't got the unit working since it was installed a week ago but expect alot of pushback on taking the unit out. Last thing I want is to start replacing different parts like compressors and switches until something clicks right. Somethings not right, either the condensor to coil match or the TXV valves.

Hello,

Sounds like it might be a couple of issues. First thing I would inquire about is why the condensing unit is shutting off... Is it off because the system Tstat has been satisfied? Are there any pressure switches on this particular condensing unit? If so, are they opening during operation? If so, either a low or high pressure condition exists and will need to be addressed. One scenario could be moisture remaining in the system that eventually freezes at the TXV. This would eventually restrict the flow of liquid refrigerant, causing low suction pressure. Telltale symptoms include the observation that it "runs fine for a while" then just stops. Or, maybe the unit is going out on a high pressure condition... Think overcharge or non-condensibles in the system. Either way, it sounds to me like the install company needs to spend more time troubleshooting/repairing and less time parts changing.

As far as the unit failing to restart, as already mentione above, most definitely sounds like a hard start kit is needed. Common problem with a TXV system. Simple relay and start capacitor will solve that problem.

Ken

Got the third TXV valve replaced yesterday. Finally system is now working as it should.

Condenser unit starts when called for cooling and temp deltas are 20-23 deg. He ordered this one with Trane's recommendation rather than using the TXVs from their inventory. His next step would have been to get a Trane rep in to check the unit out but hopefully, this will be it!.

Thanks for all the help on this site. It really helps to know what questions to ask to avoid getting too frustrated and allowing the Techs to do their job but also making sure we're not getting the run around.

I had the same experience with traine they have an electronic txv. I used a heat paste to avoid damage to the txv. The txv was bad grom factory I got a replacement and it was bad. They had no more txvs. I had no option but to replace the entire system. I never bought those units again. The customer was mad in 2011. I hope that he reads your post.