Nordyne 2.5 ton with matching add on coil to carrier furnace

[JBocc]

We attended to a service call to a nordyne heat pump. The on site tech reported back to me that they are new owners (2 months). He reported to me that the unit when checked in cooling the head pressure rose slowly then quickly to 600 psi before shutting it off the suction maintained steady at 125psi. In heating the same thing but not a fast on the rise in head pressure. I told him to pull a a pound of gas out to see it if made a difference. It improved but the pressure still rose. Noredyne is pointing toward and foouled plugged outdoor metering device, which was one of my suspicions , overcharged another, non condensibles???. Any one else got any ides ....on site tomorrow to sort this out.

[jtrammel]

Is it a dual fuel unit? Heat pump?

[jtrammel]

Is it a dual fuel unit? Heat pump?

Sorry, missed where it said heat pump. Sounds like overcharge since it is happening in heat and cool. Charge to recommended sub cooling value. Condenser coil clean?

[BaldLoonie]

Microchannel indoor coil or not?

[JBocc]

coils clean inside and out, will check on the microchannel

[JBocc]

returning to this problem this coming tuesday...For BaldLoonie whats up with the Microchannel???

[JBocc]

I also stand corrected on the model its a frigidarie .... can any one point me to where I can get subcooling values for equipment. no material on site

[ryan1088]

Micro channel coils look like car radiators. They don't have large fins on them and are made of all aluminum. They are far more apt to not like being overcharged. I'd pull the gas out and start over by weighing it in or take a bunch out to see where you're at.

[JBocc]

Micro channel coils look like car radiators. They don't have large fins on them and are made of all aluminum. They are far more apt to not like being overcharged. I'd pull the gas out and start over by weighing it in or take a bunch out to see where you're at.

Thanks, am aware of what microchannel is and have seen it..... the question was asked and it sort of left me hanging. Will post the results of what I find

[beenthere]

With a micron channel coil, charge is critical.

Pull charge, and weigh it back in.

[BaldLoonie]

We're nervous about micro channel indoor coils on heat pump. Since pumps need less charge in heat mode, having that small condenser that holds almost no refrigerant is asking for trouble. At the end of last spring we had just put in a couple and had trouble heating due to outrageous head when we got the sucker charged for cooling. With a 13 SEER outdoor unit, piston is called for. The 14 SEER calls for a TXV. We found putting a TXV on the 13s even if not "needed" helped. We also tried weighing in charge to compensate for the added lineset over 15' but that usually had us low. I don't trust mfrs. on their base charge and Nordyne seems to be low most of the time. 1 job froze up after we installed it. It had a TXV, ended up adding 2 more pounds to get subcool down.

In the days of the C6 TXV coils, didn't have these problems.

The outdoor meter is a piston. I suppose it could be plugged but cool mode, it is out of the way and not metering. In cool mode, I'd think if it were plugged you'd see a cool liquid line. Makes me wonder about non condensibles too.

[mark beiser]

I also stand corrected on the model its a frigidarie ....

You stand corrected about what? Your OP said it was Nordyne, the Frigidaire name tag doesn't change that. ;)

[JBocc]

You stand corrected about what? Your OP said it was Nordyne, the Frigidaire name tag doesn't change that. ;)

Good to know, thanks

[JBocc]

Perfect, thanks for the insight

[JBocc]

Personnaly returned today to have a look as too what I will now refer to as a " dogs breakfast".
no non condensibles
Its not a Microchannel channel add on coil... its a C6B.
Found the cool speed tap on furnace board on med -hi, changed to high speed. Was told by supplier this model of furnace has max cooling cfm of 880. So right off the hop were short for a 2.5 ton heatpump.
Ran in AC found to have 22 deg sub cool, pulled refrigerant until we steadied out at 10 deg with a 20 degree temp differential between supply and return air.
Did it ever work properly???? who knows. Did the previous owner understand how the system was to work??? who knows. Did they not use the AC...who knows????
Feel sorry for the new owners of the home.
Will see what happens