Missing TXV?

[romac]

:confused: Hi guys. I am licenced but I have to learn still bunch of things. I moved in to a doublewide mobile home and some one before stole the condensing unit outside from this split system. Some technician installed used heatpump Carrier 3 ton unit which doesn't have TXV but on its sticker it says: Indoor TXV subcooling. I don't remember to see anything like that inside the evaporator but I might have to get in there one more time plus I saw in the past TXV's inside other condensing units. The unit I have now was fitted before it was installed here with something else what I might not have. The unit was undercharged about 2Lb of R22. I remember some other technician before I was licenced didn't want to charge it full cause it was rising the presure. Just recently I opened the system and recharged to the recomemded 6.38Lb or refridgerant. I am getting 55F from the evaporator but the High is around 350-375psi and Low is 80-85psi at 110F outdor. Almost 15amps is drawn by the compressor of 18RLA. I suspect that I don't have the TXV and if I am correct can I brasse to the condensing unit some TXV from the store I can get? THX

[The MG Pony]

First off I'd check for non condencibles, and ensure the evap is matched to the unit, TXV or Cap tube dosn't matter, what matters is that it is of the correct capacity.

Secondly the TXV would be at the evap for an air conditioning only unit, heat pump would have one inside the unit as well.

The unit was used you say? Did they change the oil or pull at least a full vacuum with a new F/D? Did they purge well brazing it on?

Some thing is sounding very dodgy about this.

[lana]

Hi romac,

As MG Pony said the TXV or cap tube has nothing to do with high discharge pressure.

High discharge pressure is due to three reasons :

1- Excess refrigerant.
2- Non-condensible present.
3- Lack of condenser capacity.

The first two items above make the sub-cooling to rise, but the third reason decreases the sub-cooling value.

It is relatively easy to diagnose.

Good luck

Cheers

[romac]

Hi.
I don't know how to check for non condensibles but I checked for accid and no accid present. I assumed there might be some after I recovered the refrigerant last week so I vented a bit before charging it back and naturally I pulled full vacuum on the system before and purged hoses.
I contacted the manufacturer to help me figure out if my system is matched up but they sent me instead only an offer to sell new A coil so I don't expect to get any help from these guys.
Here are the specs: condensing/heat pump: Carrier, Model-HA1CJ036-A (3 tons?)
Evaporator Nordyne: model-C1DA-046U-B (4 tons?)
Is there any table or guide so I can carry with me all the time so I would be able to determine if units are matched up?
Since it's a heat pump it should have the TXV inside the cond. unit but it's not really there but again I don't know what was here before the original unit got stolen so to see if there is a match up I would have to look at the evaporator? If evap. is 4 tons and heat pump is 3 tons I really don't have any idea where to get the information about matching these parts.
Filter/Dryer is new as well and when I moved in the home the replacement unit was already here so I don't know if they changed the oil and if they purged while brazing the F/D on it.
To check the oil level do I have to remove the compressor and pour the oil content out in order to measure it plus there might be some oil still in the evaporator and piping?
Yes the unit is used and replaced for what was stolen from here.
I shouldn't have Excess refrigerant since I was using a scale while charging it last time.
Then I need to know how to check for noncondesibles and if you suspect some present how much to bleed out. Also how to check for condenser capacity or possible internal blockage (coils are clean).
Thanks again.

[lana]

Hi romac,

First measure the sub cooling.

For non-condensible check the link below post #5.

http://www.refrigeration-engineer.com/forums/showthread.php?t=7328&highlight=condensible

Cheers

[The MG Pony]

You don't purge! you recover the refrigerant into a tank, set aside some where cold as plausible, pull a min of a 500-micron vac, lower is better though and let site there for 30-1 hour. Now go back to your tank and look at the PvsT chart, if it matches, no prob, if it is higher then the temp, open the valve ever so little until a tiny bit of gas escapes, check again, repeat till the P&T Match.

This is of course if it is due to non condencibles.

[romac]

Tnanks MG Pony, while I was writing this post I didn't noticed your post so I am going to do what you are discribing and then come back. What I ment with the purging that I purged hoses before charging to make sure there isn't any air since I knew it's rising the head pressure.
I can't pump down as it's described in the post since the low side back seating valve was removed by some one but I checked for accid presence and the content is clean. About a year ago the refrigerant was put in new with the F/D and both low and high side right while charging was showing higher pressure. Low 80-85Psi, High 350-375psi at 100F outdoor and at the full capacity of 6.38Lb of R22. The guy noticed it so he removed some of the ***** in order to lower the presure and told me it might be due to the unmatched evap./cond. which is:
Evap:4 tons and cond. 3 tons each different brand, Nordyne/Carier. Some one told me if the evap. is bigger it's not that big problem.
THX again.

[The MG Pony]

I don't purge my hoses, refrigerants to valuable for that, I instead pull a vacuum in the hose set via the pump then charge the system, once system is running and the charge is set, I turn off the valve at the tank and then pump down the system and let it draw a vacuum on the LS, at this point the HS valve is shut off from the gauges, I then open both the low and high side valves ON the gauges so they can be vacuumed out by the LS port on the machine. So when both the HS & LS valves are closed there is a vacuum in my hoses, virtually no gas is wasted aside from vapour of such insignificant amount remaining in the gauge set. It is a slightly slower methode, but it reduces escaped refrigerant by such a larg degree it is worth it to me.

[Lowrider]

I don't purge my hoses, refrigerants to valuable for that, I instead pull a vacuum in the hose set via the pump then charge the system, once system is running and the charge is set, I turn off the valve at the tank and then pump down the system and let it draw a vacuum on the LS, at this point the HS valve is shut off from the gauges, I then open both the low and high side valves ON the gauges so they can be vacuumed out by the LS port on the machine. So when both the HS & LS valves are closed there is a vacuum in my hoses, virtually no gas is wasted aside from vapour of such insignificant amount remaining in the gauge set. It is a slightly slower methode, but it reduces escaped refrigerant by such a larg degree it is worth it to me.

Beside the cost of refrigerant, it's also the way it should be done, or at least I think so! No refrigerant should be lost, but we should at least keep it to a minimum.

[romac]

I am back guys and I have to apologize for confusement I created. My JB gages were reading on the high side 60psi more than it suppose to. I connected it to new R22 in green bottle and it was still too high so I new where the problem was. I put different gages on and the problem is gone. I don't get what happened to the gages. Is it possible that some one connected it before me since it's used to something like 410A system and made some damage to it. Did it ever happened to any one else that gages were reading more than they suppose to? Thanks to all again.