High Pressure Lock Out - Capacitor, Compressor, TXV or something else?

[KB99]

I have a Lennox XP13-048-230-01 Heat Pump
Recently it has started happening 2-3 times a day that the Heat Pump will shut off after running several hours. It will come back on if I turn the breaker off and back on. The Defrost Control Board was showing solid green light on the DS2 LED indicating High Pressure Lock Out. I did all the maintenance stuff like of course changing the air filter (which I do regularly) cleaning the condenser coils (inner and outer), and cleaning the evaporator coils. The fan runs plenty fast and pushes up hot air when it is running. After I exhausted everything I could figure out I caved and had a technician out and I'm not feeling super confident about what he told me though it may just be because it wasn't what I expected.

Of course you'll all want specs as well as the measurements he took to make heads or tails of this so here we go:

System Specs (Obviously I can't put everything so I tried to pick out the most relevant)
13 Seer
Rated Load Amps - 21.79
Subcooling for Normal Operation - 7 degrees F
Approach Value for Normal Operation - 11 degrees F
Liquid Line Pressure +or-10 / Vapor Line Pressure + or -5 at 85 F - 318/143
Liquid Line Pressure +or-10 / Vapor Line Pressure + or -5 at 95 F - 369/145


Measurements
Geographic Location - Central Florida (Lots of Heat and Humidity)
Outside Air Temp - 92 F
Refrigerant Type - R-410A
Suction Line Pressure - 125.5 PSIG
Vapor Saturation - 43.1 F
Suction Line Temperature 73.7 F
Actual Superheat - 30.6 F
Liquid Line Pressure - 329.6
Liquid Line Saturation - 102.4 F
Liquid Line Temperature - 102.0 F
Actual Subcooling - 0.4 F
AMPs while running - 21.83


I expected that he would tell me that there was likely an issue with the TXV valve that would be causing the high pressure lock outs, but before he even got to measuring the pressures he saw the AMPs while running and was telling me I probably need a new compressor. When he left he gave me choices to try ranging from replacing the Capacitor (), replacing the Compressor (), or replacing the TXV (). He was definitely of the opinion that the Compressor was about to go. Plus he was giving me the push over "wouldn't I like to have a more energy efficient system" when honestly I'd rather save my money right now for me and my two kids living in the house for the other things we need unless I really need a new system.

Other random info if it is helpful, it is for a 2,600 sq ft one story single family home. The air handler is in the garage and of course the heat pump is outside.

I'd love if some of you folks can validate whether replacing the Compressor or getting a whole new system is really the way to go or if the numbers here indicate something else, or if there is something else that needs to be checked.

[pecmsg]

1St
Pricing is not allowed, its a regional thing.

2nd
Are you licensed to be connecting gauges and taking readings?

[KB99]

I'm sorry about the pricing. Regarding the readings, I was just including the information provided by the technician. I didn't take the readings. I'm sharing what he provided to me. I don't want to do any of the work myself, I'm just wanting the right work done.

[jacob-k]

Looks undercharged to me.

No issue with high head pressure

Certainly would not recommend any kind of replacement based on those numbers. More investigation is required

Sent from my SM-G998U using Tapatalk

[Snapperhead]

Those amps lean toward a weak Capacitor also ...

For that price I hope he uses AMRAD USA made capacitor ...

[Bazooka Joe]

Outdoor fan shutting off? Short of sitting there and watching it, may be a tough find what’s causing the high pressure lockout, even with gauges hooked up. Thinking the HPC cuts out at a much higher pressure than what your running at, to prevent nuisance tripping and lock out.

Thinking if it trips at 2 to 3 times a day, you should have a idea of how long it runs before it trips ( if thermostat never satisfied ) then when that time period gets close watch your high side gauge and outdoor fan motor or just pay attention for any abnormalities.

You don’t mention how old this system is?

[pacnw]

Those amps lean toward a weak Capacitor also ...

For that price I hope he uses AMRAD USA made capacitor ...

RLA 21.79
LRA 117

[pacnw]

Looks undercharged to me.

No issue with high head pressure

Certainly would not recommend any kind of replacement based on those numbers. More investigation is required

Sent from my SM-G998U using Tapatalk

Actual Superheat - 30.6 F
Actual Subcooling - 0.4 F

[jacob-k]

Actual Superheat - 30.6 F
Actual Subcooling - 0.4 F

Are you saying you see something different or are you agreeing?

[pacnw]

Are you saying you see something different or are you agreeing?

Agreeing nad just pointing to some numbers to point in that direction for the OP to use when asking questions of the onsite tech.

[mgenius33]

I’d be looking at the condenser fan overheating, and possibly slight undercharge.
Fan over heating can be due to bearings or low capacitor. If you turn off the disconnect while the unit is running, does the fan spin more than 3 full rotations? What is the current draw on the condenser fan alone? I don’t quite understand why the cap wasn’t changed if it was bad? A bad capacitor can reduce efficiency, reduce motor speed, and increase motor heat. Does the tech actually know how test a capacitor under load, or was this a guess?
Also, I would make sure that condenser was cleaned properly from the inside out. Were the measurements taken while the coil was still wet from cleaning? If so, this could explain the low subcooling.
You’re system is drawing way too much current.

Hope we’re not crossing the DIY line here…
No necessarily for this person, but in general.

[BNME8EZ]

Looking at the numbers I would agree with the undercharge, I would also be checking the cap because of the amp draw. If it is a dual cap then it could be causing the fan to drop out.

One other thought to the OP, do you hear any odd noises when it is running. Thinking something like shifting into defrost. I haven't seen a newer system do this but have seen bad sensors cause the defrost board to think the system needs to go through defrost which drops the outdoor fan. This would cause a HP lockout. My 1st thought was you may here the valve shift but it is already in defrost position so scratch the odd noise part.

You may also want to seek a different tech if he looked at these numbers and concluded a bad compressor.

[KB99]

Outdoor fan shutting off? Short of sitting there and watching it, may be a tough find what’s causing the high pressure lockout, even with gauges hooked up. Thinking the HPC cuts out at a much higher pressure than what your running at, to prevent nuisance tripping and lock out.

Thinking if it trips at 2 to 3 times a day, you should have a idea of how long it runs before it trips ( if thermostat never satisfied ) then when that time period gets close watch your high side gauge and outdoor fan motor or just pay attention for any abnormalities.

You don’t mention how old this system is?

The heat pump is able to shut it self off once the temp inside the home meets the temp set on the thermostat and it can come back on independently when the temp goes up. So it's functioning ok some of the time. The trouble with figuring out when it will shut off is that sometimes its in the middle of the night/wee hours of the morning. The only way I notice is when it starts to get hot inside the house. I'll try going out maybe every hour to check on it so I can get a better idea of how many hours in between lock outs. I also haven't heard any strange noises coming from it. To answer your last question, it appears the system is from 2006. I've only lived in the home since last Sept. so I can't speak to much of its maintenance history or how it was last summer or anything like that.

[KB99]

Looking at the numbers I would agree with the undercharge, I would also be checking the cap because of the amp draw. If it is a dual cap then it could be causing the fan to drop out.

One other thought to the OP, do you hear any odd noises when it is running. Thinking something like shifting into defrost. I haven't seen a newer system do this but have seen bad sensors cause the defrost board to think the system needs to go through defrost which drops the outdoor fan. This would cause a HP lockout. My 1st thought was you may here the valve shift but it is already in defrost position so scratch the odd noise part.

You may also want to seek a different tech if he looked at these numbers and concluded a bad compressor.

I haven't heard any odd noises while it's running. I'm not 100% on whether it is dual cap or not. There does appear to be two capacitors with the other components in the heat pump. Once I've met my minimum posting quota I can share a picture of what's in there. The system I believe is from 2006, so it's definitely not new.

[Bazooka Joe]

Dated 2009 reading it the fault light locks out the system after a high pressure condition occurs ( single demand cycle ) after the 5th time not the 1st time it occurs ( Page 23 ) if single demand cycle means the unit cycles off after thermostat satisfies then your system should be tripping more frequently ( you may be able to catch it ) as it takes 5 times before it actually locks out??

https://www.google.com/url?sa=t&rct=...h0wDCxsO_hfwyD

[KB99]

I’d be looking at the condenser fan overheating, and possibly slight undercharge.
Fan over heating can be due to bearings or low capacitor. If you turn off the disconnect while the unit is running, does the fan spin more than 3 full rotations? What is the current draw on the condenser fan alone? I don’t quite understand why the cap wasn’t changed if it was bad? A bad capacitor can reduce efficiency, reduce motor speed, and increase motor heat. Does the tech actually know how test a capacitor under load, or was this a guess?
Also, I would make sure that condenser was cleaned properly from the inside out. Were the measurements taken while the coil was still wet from cleaning? If so, this could explain the low subcooling.
You’re system is drawing way too much current.

Hope we’re not crossing the DIY line here…
No necessarily for this person, but in general.

I pulled the disconnect while it was running and the fan kept spinning for maybe 30 seconds or so. He did check the amps on the condenser fan but I don't remember what the number was and he didn't include it in what he sent back to me with the other diagnostics. Regarding the capacitor, he said, and I hope I am getting this close, was that he could put a capacitor with a hard stop. But it sounded to me when he was explaining it that it would throttle the amps on start up but I didn't see what that would do to address the amps while it was running. I had done the cleaning of the heat pump coil 2 days before the tech was out and it hadn't rained or anything, all that to say it wasn't wet when the tech was taking the readings. Once I meet the minimum posting quota I can share pictures of the diagnostics and the other components in the heat pump.

If anything I say or ask crosses the DIY line, please let me know. I appreciate the help but I don't want to take advantage.

[KB99]

Dated 2009 reading it the fault light locks out the system after a high pressure condition occurs ( single demand cycle ) after the 5th time not the 1st time it occurs ( Page 23 ) if single demand cycle means the unit cycles off after thermostat satisfies then your system should be tripping more frequently ( you may be able to catch it ) as it takes 5 times before it actually locks out??

I'm doing my best to follow here. So are you saying I should try to see if I can watch when the heat pump shuts off after the inside temp has met the desired temp on the thermostat? And if I have that correct, what am I watching/listening for?

[Special-K]

Pricing removed

[BNME8EZ]

He is saying for the code to appear the fault has to occur 5 times while the system is running on the same cycle (thermostat on to thermostat of). So on a 100 minute cycle it would happen about every 20 minutes or less. More than likely it will run for 75ish minutes then cycle off on HP every 5 minutes.

[KB99]

Pricing removed

Thank you. I'm sorry about that.