HVAC A/C Heat Pump Failure

[Supervstech]

We do this for a living. Do you know how many times a customer reset the breaker and it started working perfectly again? 1 out of 10, usually due to brownouts. Do you know how many times they called me back two days later saying it was broke again? 9 out of 10. Do not reset a tripped breaker until a professional looks at it. You’ll usually do more damage to a unit. Like burning holes in refrigerant lines where your wiring shorted due to vibration and lack of tie wraps. Like burning your compressor up due to a bad capacitor. Like setting your entire electrical compartment on fire. Like blowing the compressor terminal out the side of the compressor, catching the oil on fire ? flames shooting from fan outlet. Like turning your electric heat elements bright and molten, dripping down inside your crossover flex duct, catching it on fire. Like turning a 10 ga Romex wire bright red, in crawl space going to a shorted compressor where the cheap guy or DIY’er installed an oversized 60A breaker. There’s many more. Don’t reset a breaker unless you’re sure it was a brownout condition. If you have more than one brown out a year and I would advise getting someone to install brown out protection on your unit, then you won’t have to worry about tripped breakers. Also, don’t install one big system because it’s cheaper. Install two separate smaller systems. Then you’ll have redundancy in the middle of the night when one heat pump quits working.

Exactly!

 

[Supervstech]

Customer, lol.

When it is cold out and the family is freezing, it is perfectly reasonable to reset a blown breaker. Your reply added little value.

I assure you... to those that listen to my advice, there is great value.

Please be certain the cause of a tripped breaker is determined before resetting it.

It is a possibility a breaker tripped for non critical reasons... but as a professional, it is a very low percentage...

 

[RV10flyer]

For an additional $300 one can save an inverter based system or any HVAC circuit board containing equipment. I’ve replaced at least five of mine in the last 10 years where lightning struck directly or nearby. No damage to the equipment.

This is one example: DITEK's DTK-KG2 is part of the Kool Guard family of voltage monitoring products. It is specifically designed to protect HVAC equipment from harmful undervoltage and overvoltage events that can damage sensitive electronics and mechanical components within the system. The DTK-KG2 also incorporates DITEK's state-of-the-art surge protection design to shield the equipment from damaging transient voltage surges and spikes. The standard UL Type 4X polycarbonate enclosure allows the unit to be easily installed in harsh outdoor environments.

Product Features:

• Protection for undervoltage and overvoltage events on 120/240VAC or 120/208VAC split phase circuits up to 40A
• Auto-calibration feature eliminates the need to manually calibrate the unit to the specific input voltage
• Safely disconnects power to the system for 3 minutes allowing input voltage to return to normal range
• Ideal protection for inverter-driven compressor systems and mini-splits
• Diagnostic red and green LEDs indicate exactly what voltage condition is present
• Surge protection components included to divert harmful transient voltages away from the equipment
• Accepts either 1/2" or 3/4" NPT flexible conduit
• UL Listed

Product Specifications:

• Operating Frequency: 50/60Hz
• Max. Continuous Current: 40 Amps
• Under-voltage Protection Level: 104VAC (L-G)
• Over-voltage Protection Level: 130VAC (L-G)
• Short Cycle Delay: 3 Minutes
• Surge Current Rating: 50,000A
• Connection Method:
  • Series-wired, 1/2" or 3/4" NPT Conduit
  • Hardwired lugs: 8 AWG Max
• Housing: UL Type 4X Enclosure
• Dimensions: 6.29" L x 6.29" W x 2.36" H
• Weight: 3 lbs
• Certifications: UL 60947-1 Listed; UL 60947-5-1 Listed

And another brand I’ve used…..

Rectorseal 96421 RSH-50 VRM Kit​

 

[kromc5]

For an additional $300 one can save an inverter based system or any HVAC circuit board containing equipment. I’ve replaced at least five of mine in the last 10 years where lightning struck directly or nearby. No damage to the equipment.

Rectorseal 96421 RSH-50 VRM Kit​

That is very interesting I like the rectorseal as it has some logging built in, did not see that on the dtk.

 

[JCSchwarb]

Do you think your inverters or AC are related to the GFCI issue?
Does the GFCI issue change with the AC disconnected?
Do you have a GFCI breaker on the AC? Is that the GFCI giving issues?
Have you already replaced the failed board?
Do you know the default neutral ground bond condition on those inverters?

Inverters are the culprit for sure. No issue in bypass or when sufficient battery voltage or PV input. No GFI on Heat pump, but I did order a surge protector that I plan on installing. Have not replaced the CCA yet. Wanted to get everyone’s thoughts first so I don’t have another mishap. These items take weeks to get. Have been down since 12/24

 

[JCSchwarb]

That is very interesting I like the rectorseal as it has some logging built in, did not see that on the dtk.

Rectorseal is a very interesting marketing name.

 

[timselectric]

Rectorseal is a very interesting marketing name.

It just makes me laugh.
Don't confuse it with a suppository.

 

[bhavin66]

After reading some on the MrCool Universal I guess if my current condenser failed then I would retrofit my current A/C gas furnace with a MrCool HP and make the gas furnace second stage. In the summer months we use the evaporator cooler as primary but during monsoon season when the humidity is high switch over to the central A/C. Thanks for calling attention regarding MrCool HPs as it has been decades since I have had to deal with those. Haven't familiarized myself with inverter HP tech.

I have the setup when MrCool heat pump is primary and the gas furnace is secondary. I have 2/3 ton setup as 3 ton and set to go to secondary below 25f and everything has been fine so far the last year or so here in NJ. During the cold freeze a few weeks it ran the gas furnace and my ecobee kept complaining that secondary is running more than certain hours please check the system but I knew it was freezing and gas furnace had kicked in so all good.

 

[JCSchwarb]

I have the setup when MrCool heat pump is primary and the gas furnace is secondary. I have 2/3 ton setup as 3 ton and set to go to secondary below 25f and everything has been fine so far the last year or so here in NJ. During the cold freeze a few weeks it ran the gas furnace and my ecobee kept complaining that secondary is running more than certain hours please check the system but I knew it was freezing and gas furnace had kicked in so all good.

Excellent. Replaced the entire board today, but getting code PH which is a high voltage bus alert. The unit then shuts down. Not sure what is causing it. Voltage remains steady during the entire cycle at 238.5 across L1 and L2.

 

[NEpowerandlight]

I have the setup when MrCool heat pump is primary and the gas furnace is secondary. I have 2/3 ton setup as 3 ton and set to go to secondary below 25f and everything has been fine so far the last year or so here in NJ. During the cold freeze a few weeks it ran the gas furnace and my ecobee kept complaining that secondary is running more than certain hours please check the system but I knew it was freezing and gas furnace had kicked in so all good.

Curious why you have go secondary at 25F?

 

[bhavin66]

My HP unit is still on grid just the fan is on off grid inverter. Did you try to contact Mr Cool support? Did you check your grounding?

 

[bhavin66]

Curious why you have go secondary at 25F?

Because I have a gas furnace that is available to me that I can use, no other reason.

 

[NEpowerandlight]

Because I have a gas furnace that is available to me that I can use, no other reason.

Thanks

I asked because I also have a gas furnace as my secondary and a combined 30k BTU's of mini split units as my primary. On 12/23 we hit -2F up here near the Poconos and both systems were blowing enough heat. I was surprised because I plan to add another 12K unit. I considered my systems a little undersized for heating purposes but they work great when temps reach single digits.

 

[daklein]

house shows other unbalanced issues in the GFCI circuitry when the battery voltage gets low or when system enters bypass mode. I am running six (6) EG4 6500EX in split phase

What sort of unbalanced issues? do you mean seeing other than 120v on both legs? could be loose neutral somewhere or some circuits.

 

[OilCan]

Excellent. Replaced the entire board today, but getting code PH which is a high voltage bus alert. The unit then shuts down. Not sure what is causing it. Voltage remains steady during the entire cycle at 238.5 across L1 and L2.

Their documentation shows
2. Unit operating power must be within the nominal range stated in the instruction manual. Use a
specialized power circuit for the air conditioner. Do not draw power from another power circuit.

They indicate a range of 208-230V, hope that is not a strict MUST. I highlighted must in bold.

 

[JCSchwarb]

Their documentation shows
2. Unit operating power must be within the nominal range stated in the instruction manual. Use a
specialized power circuit for the air conditioner. Do not draw power from another power circuit.

They indicate a range of 208-230V, hope that is not a strict MUST. I highlighted must in bold.

Mr Cool Universal Condenser Compressor died after one week of commissioning my new solar system. Unit was only one year old.

 

[OilCan]

Mr Cool Universal Condenser Compressor died after one week of commissioning my new solar system. Unit was only one year old.

Were you able to meter out the compressor for a short, open or ground? I have no familiarity with the durability of the inverter type compressors but it seems the national brands such as Trane, Carrier and Goodman are into making them. Perhaps the original board failure also took out the compressor?

 

[JCSchwarb]

Were you able to meter out the compressor for a short, open or ground? I have no familiarity with the durability of the inverter type compressors but it seems the national brands such as Trane, Carrier and Goodman are into making them. Perhaps the original board failure also took out the compressor?

yes, it was a dead internal short. I originally was going to test this, but the manufacturer techs didn’t think it was necessary based on failure mode.

 

[Solar Guppy]

yes, it was a dead internal short. I originally was going to test this, but the manufacturer techs didn’t think it was necessary based on failure mode.

Your 50 amp breaker is likely why the compressor is toast, a 50 amp breaker is going to melt the windings before it trips. Take a look at the trip curves to understand why.

The 4/5 Ton is listed for a MAXIMUM of 50 amp and a minimum circuit of 29 amps, and run of 22 amps, I would use a maximum of 30 amp breaker on the compressor.

On my MrCool 2/3 Ton universal ( different model than yours ) I'm running a 15 amp breaker and its ice cold.

 

[JCSchwarb]

Your 50 amp breaker is likely why the compressor is toast, a 50 amp breaker is going to melt the windings before it trips. Take a look at the trip curves to understand why.

The 4/5 Ton is listed for a MAXIMUM of 50 amp and a minimum circuit of 29 amps, and run of 22 amps, I would use a maximum of 30 amp breaker on the compressor.

On my MrCool 2/3 Ton universal ( different model than yours ) I'm running a 15 amp breaker and its ice cold.

Appreciate the feedback. I may step it down, however the CB did trip. When I reset it on a cold morning, the PCB blew.