What does error code 4 "Locked Rotor" on a Daikin DZ16TC mean?

[MycoAstroNS]

I had a Daikin DZ16TC (3 ton) with DV37PTCD14 air handler installed 1yr and 9 months ago. This winter I noticed that the outdoor unit fan wasn't running even though the thermostat said heat was on and realized that it was using auxiliary heat and not the heat pump unit. First thing I did was check the electrical panel and discovered that resetting the circuit at the panel caused the outdoor unit to start running again. I hoped that it was a one-off problem but it happened again multiple times so I called the installer and they did a service call. Here's the thing, the installer tech said it was showing Error 4, which he said means "Locked Rotor" but after a couple of hours of testing and tightening up wires, etc said that he couldn't find anything wrong and he hoped that he inadvertently fixed it. It's not fixed. Every 2 to 10 days the outdoor unit stops working and I have to reset the breaker at the panel to make it work again.

Before I call them back for a service call, I'd like to know more about this Error 4 "Locked Rotor" so that I'm more knowledgeable about the problem and can advocate to get this fixed. I'm reluctant to order another service call and for them to tell me they they can't find anything wrong. Clearly something is wrong - one shouldn't have to trip the breaker every 2 - 10 days to keep it running.

Thanks for the help.

[VTP99]

Yeah you're not crazy something isn't right.
Lock rotor is never a good thing especially if it eventually doesn't unlock 😲
Not to panic thou because it could be a simple fix with a competent set of eyes on the system.

[pecmsg]

Call them back, they said it was fixed!

[rundawg]

Fault 4 (Locked Rotor) - is an electrical or mechanical issue with the compressor.

It sounds like your tech checked all the external electrical components that could be the cause of this problem, but with your problem being intermittent, it may be hard to diagnose.

A mechanical issue with the compressor (bad bearings or windings) may take longer to present themselves on every start up.

If you don’t reset the unit when it fails next time, the tech might be able to get a better idea of where the problem lies when he starts troubleshooting.

[Bazooka Joe]

Hopefully you registered your outdoor and indoor section as if the compressor ever fails in the 1st 12 years you get a one time new outdoor unit, not a replacement compressor.

Quebec or California need not to register to receive full manufacturers warranty.

They show as a optional a OEM hard start kit page 25?

https://www.google.com/url?sa=t&rct=...W3gW1VWAQoKtP7

That model has a Advanced Copeland CoreSenseTM Technology compressor protector.

May want to have the Installing Contractor call Daikin Technical Representative for guidance? Typically Technical Rep. does not deal with homeowners, only Contractors.

[MycoAstroNS]

Thanks for the responses. What I'm taking away is that the reason it's hard to diagnose is that it could be anything from a loose wire to a compressor failure? @rundawg I did leave the outdoor unit in the fault condition when the tech came for the service call so he did have the opportunity to diagnose, but as soon as the circuit was reset the fault goes away and everything runs fine. So it sounds like the recommendation would be to wait and see if the problem becomes more frequent, like it's occurring whenever the thermostat calls for heat. At that point it should be pretty easy to diagnose. @Bazooka Joe good to know that I can get a whole outdoor unit replacement.

[pecmsg]

There are several things that can cause LRA on start-up, electrical is just one. Ask the contractor to send a more experienced tech.

[VTP99]

With the CoreSense high discharge temperatures to name just one.
As for code#4
Compressor trips within a run time of 12 seconds and does not start within 35 seconds.

[pecmsg]

High discharge temperatures to name just one.

High Superheat

[Bazooka Joe]

Do you have a 5 minute off cycle time delay at the thermostat? What breaker size are you running for the outdoor section? Did they reuse the old existing breaker? If so what’s the rating and did the tech. pull the breaker and checked the contact connections? or check the breaker itself? The install guide says minimum HVAC type breaker is 20 amp. maximum 30. What are you running now?

Thinking new system new breaker, it’s not a terribly expense part for a Contractor.

Says this under notes: Must use time-delay fuses or HACR-type circuit breakers of the same size as noted

https://www.google.com/url?sa=t&rct=...W3gW1VWAQoKtP7

Page three for a three ton, or check the outdoor unit electrical data plate for what the manufacturer wants for breaker size.

[MycoAstroNS]

@Bazooka Joe,

I recollect that the tech set a 5 minute cycle time delay as he made a big deal about that needing to be set.

New breaker; 30 amp. No idea if it's a HVAC type breaker but they had an electrician in to do all the wiring and connecting to the panel so I assume they did it correctly?

That's all I know,
Keith

[timjimbob]

Had similar issue with inverter heat pump. Armstrong manufacture. Intermittent locked rotor error. Simply, it was bad cch.

[MycoAstroNS]

Thanks @timjimbob. I’ll pass that along to the service tech. But “cch”?

[Sleuth]

Thanks @timjimbob. I’ll pass that along to the service tech. But “cch”?

.
CCH...crank case heater.
..

[Bazooka Joe]

If wiring diagram is accurate and reading it correctly shows Crankcase Heater and the Crankcase Heater Switch as optional, ( page 23/24 ) check yourself by base of compressor for any wires. Certainly you can have one, have them check the CCH if one is equipped.

https://www.google.com/url?sa=t&rct=...W3gW1VWAQoKtP7

Dated 11/2019

[timjimbob]

Without cch, cold compressor has liquid refrigerant that doesn’t compress as gas would. Compressor stalls. Heater “boils” liquid and turns it to a gas that the compressor can pump.
Allied tech help did not offer this solution when asked about the locked rotor code. Thanks to my inquisitive tech he solved this problem.

[timjimbob]

Reading the schematic, looks like a 120 volt heater, on leg tied to the ground. That’s illegal

[pecmsg]

Reading the schematic, looks like a 120 volt heater, on leg tied to the ground. That’s illegal

Only if they get caught!

[timjimbob]

Must be an error. Also a direct short