Need help diagnosing Goodman heat pump problem

[HomesteadHVAC]

I have been in the hvac industry for 17 years but heat pump repairs are not too common for me. I want to be great at what I do but lack experience in this area.
I was called to a one year old Goodman heat pump install that was apparently noisy, gave no heat, and froze up in heat mode. I like to start from scratch so I checked out everything. It is a 5 ton, 2 stage unit but it was only wired as a single stage, the thermostat setting were all wrong, the blower was only moving 1300 cfm, the furnace has return air on right side only(no way you can move 2000 cfm through that), capillary tubes off outdoor txv were rubbing and vibrating so much that they almost made a hole in the tubing. Phew, I think that's most of it. I am trying to be thorough.
It has a piston at the coil but I have not checked the size yet. I had 5 degrees of superheat, with a 57F od ambient and 51F wet bulb. It works well in cooling mode. I switch to heating mode, and it runs for only a few minutes before the outdoor txv freezes up and the compressor shuts off. The condensor fan continues to run so I assume this is the defrost cycle?
I really want to learn so could you please help me understand?

[mark beiser]

Well, you definitely don't have enough indoor airflow.

Those old Goodman 2 speed units specifically REQUIRE a TXV on the indoor coil. It is in the installation instructions AND on a sticker on the control box cover inside the unit.
With that system, there is no such thing as "correctly charged" if it has a fixed orifice on the indoor coil.
With just having an orifice inside, I would strongly recommend against "fixing" the control wiring to allow 1st stage to run by itself.
If you were to fix it so it would use both stages, and adjusted the refrigerant charge so it is "correct" in 2nd stage, the system will be over charged for 1st stage.
If you adjust the charge so it is "correct" in 1st stage, the system will be under charged for 2nd stage.

The condenser fan still running when the compressor shuts off is an indication that it is NOT in defrost.

On those units, the condenser fan is switched on and off by the control board in the unit, so will stay running if the compressor is turned off due to a low or high pressure switch tripping, or the compressor protection module turning the compressor off due to the compressor windings getting to hot.

You didn't really give enough information to know why the outdoor TXV ices up in the heat mode, or why the compressor shuts off, but they could be related.
If the outdoor TXV is failed closed, the system would operate "normally" in the cooling mode, but in the heating mode the TXV and distributor tubes can/will frost up, and the low pressure switch would open, causing the compressor to turn off.

[beenthere]

Kind of sounds like they knew it had a problem when it was installed. So they left it only able to run in first stage to prevent the system from locking out on high head in heat mode, and low pressure in cool mode.

Sat pressures and temps help us to help you. Along with all temp readings including the inside temp.

[hvacvegas]

As far as the staging goes:

There are some tech's, on heat pumps, that abandon first stage. Homeowner complaints about air temp tip their hand. Then it seems like the HO never calls to complain again.

Personally, I think I would fix the installation issues and then try and charge the system.
Charging a 2-stage heat pump, without a txv, is gonna give you problems.
Model #'s?

[dandyme]

1st_ I'll take your word that you're a tech, nothing in the profile to confirm or deny

2nd_ not near enough information as stated above

discharge_ psi & temp
suction_ psi & temp
liquid_ psi & temp
ID temp
coil condition ID & OD

that'll give us a clue what's happening

[HomesteadHVAC]

Sorry, you're right. I have more info to offer but with 2 young children and performing heat loss/gain calculations in the evenings, I guess I rushed.
I am a tech and will fill out my profile ASAP.

Furnace model was the variable 95090 with 5 ton blower. Sorry, didn't record it.
Heat pump model number is SSZ160601AE
Indoor coil model not known but is an 060.
Condition of both coils is good and clean
Outdoor ambient is 57F
Indoor temp is 66F
Indoor wet bulb is 51F
Suction pressure is 101 psi
Suction line temp is 37F
Liquid leaving temp is 57F
Liquid pressure is 173
R410a system

Yes, it was running on 2nd stage only. Maybe the original tech knew of a problem. He was a refer mechanic in his 60's but passed away a month ago. I've been to several of
His jobs that look and work great but this one is out of his character.

Anyway, I hope this all helps. I am suspecting a failed outdoor txv. What would cause it to fail closed?

[dandyme]

is that liquid psi from the small pipe or the insulated pipe?

txv failure-cap tube rub, crimp around head of txv leak, previous leak....

the info passed on will be limited because of open forum

[SandShark]

...capillary tubes off outdoor txv were rubbing and vibrating so much that they almost made a hole in the tubing. This caught my attention. Did you look at capillary tube coming from the power element.

[HomesteadHVAC]

This is liquid psi measure off the 3/8 service valve.

It should be noted that when i read pressure from the 3rd port( i don't know what else to call it), I had a negative reading. Could this be from a closed txv, which is shutting off the compressor?

I did not look specifically at the capillary coming from the power element. I assume that by this, you mean the solenoid?

[dandyme]

that psi port alone by itself is the suction psi tap in heat mode

capillary from power head to bulb


me believes you just found your problem

[beenthere]

This is liquid psi measure off the 3/8 service valve.

It should be noted that when i read pressure from the 3rd port( i don't know what else to call it), I had a negative reading. Could this be from a closed txv, which is shutting off the compressor?

I did not look specifically at the capillary coming from the power element. I assume that by this, you mean the solenoid?


The third port, is known as the true suction port. Its the suction port in both heating and cooling. And should have the same pressure as the large line when the unit is in cooling mode.

Are you sure the vapor/large line's service valve is completely open.

[HomesteadHVAC]

I have not checked to see if the service valve is completely open, however this unit has worked well up until recently so it sounds like the rubbing of capillary tubes over the months has caused the txv to fail.
I will check to see if the valve is fully open when I go back to be sure.

Do you suppose that the low airflow has caused the capillary tubes to vibrate in the first place?

[beenthere]

I have not checked to see if the service valve is completely open, however this unit has worked well up until recently so it sounds like the rubbing of capillary tubes over the months has caused the txv to fail.
I will check to see if the valve is fully open when I go back to be sure.

Do you suppose that the low airflow has caused the capillary tubes to vibrate in the first place?

Its possible.

[ga-hvac-tech]

This is liquid psi measure off the 3/8 service valve.

It should be noted that when i read pressure from the 3rd port( i don't know what else to call it), I had a negative reading. Could this be from a closed txv, which is shutting off the compressor?

I did not look specifically at the capillary coming from the power element. I assume that by this, you mean the solenoid?

Might want to read a few recent posts; remembering the highlited statement above.

[mark beiser]

Wow, I really need to not be posting at 4am.
Somehow I read the OP as being a 17 year old Goodman 2 speed unit!
Now I see that it is a 1 year old unit, which is a COMPLETELY different animal than the old mid 90's Goodman 2 speed units, so ignore most of my last reply. :o



It should be noted that when i read pressure from the 3rd port( i don't know what else to call it), I had a negative reading. Could this be from a closed txv, which is shutting off the compressor?

Yes, the 3rd port is the true suction pressure for the compressor, and is the same pressure acting on the units low pressure switch.

[HomesteadHVAC]

Thank you all for your help. I feel confident that I will be able to fix their problems upon my next visit. I will have to address the airflow issue but we'll get it done.

I'm very happy how quickly you all responded and how much you were able to help.

I will update this thread after I have been back to this site next week.

[ga-hvac-tech]

Thank you all for your help. I feel confident that I will be able to fix their problems upon my next visit. I will have to address the airflow issue but we'll get it done.

I'm very happy how quickly you all responded and how much you were able to help.

I will update this thread after I have been back to this site next week.

Get your post count up to 15, and apply for PRO status. If you are a business owner, at 25 posts you can apply for business and marketing status.

If you think H-talk has some cool stuff now... you have not seen anything until you get behind the Pro door... :)

[HomesteadHVAC]

I returned to the heat pump today and replaced the txv, filter/drier, and contactor(spider problem). After adjusting the spring on the txv, it seems to be working decently. I would say that the problem is solved and I can invoice the client.

The system is not working as well as it should be though. It is a 16 SEER unit and is using a fixed orifice rather than a txv at the evaporator. The furnace is not moving the desired 2000 cfm due to single point entry of return air(on the motor side to make things worse).

That being said, I was hired to fix it. I wasn't hired to point out all the mistakes made by the installer, since he is the one who hired me ;)

Thank you for all your help. I have learned much from this experience.

[beenthere]

masumparveg, this is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise here. Please apply to the AOPC today, thank you.

You can find the rules for posting and qualifications here (http://hvac-talk.com/vbb/showthread.php?t=957002).


Further infractions may result in loss of posting privileges.

[SandShark]

Ahh, another Goodman lives to see another day. All is right with the world.