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Old 05-10-2019, 11:32 AM   #1
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Heat Pump Diagnosis & Defrost Board Replacement Question


Helo All!

We have a Haier Heat Pump outdoor unit, model HR30C1VAR. The indoor unit is Hi-Velocity brand fan coil unit. It's a mini-duct system because we have hydronic heat.

When the thermostat calls for cooling, the unit will operate normally for about 5 or 6 minutes (varies) and then the contactor coil for the compressor and condensing fan is de-energized. After a 3 minute delay, the system starts back up and runs for a few minutes, then the coil is de-energized again.

The diagnostic LED on the board gives no code when the contactor is de-energized.

My work experience was with chillers, so I am fairly unfamiliar with heat pumps and residential units in general, thus my confusion.

To diagnose, I watched the gauges and see that it is not turning off on high pressure or low pressure safeties. I did many other tests, including bypassing the thermostat and indoor unit completely to determine if the problem was from the indoor unit or the outdoor one. I concluded the outdoor unit circuit board is the problem.

My first question is about two sensors:

One is called "Pipe Sensor" on the schematic and is called "Defrosted Sensor" on the piping schematic. The bulb is brazed on the lowest distributor tube where it enters the outdoor unit's coil. (Condensing coil in cooling mode)
The Ohm meter shows that the resistance drops as the temperature of the bulb rises. (Tested with warm air gun)
I believe this either initiates or terminates the defrost cycle based on the temperature of the tubing.

The other sensor is called "Vent Sensor" on the wiring diagram and "Discharge Sensor" on the piping schematic. It's bulb is brazed to the compressor discharge line just before the reversing valve.
I can only guess (and this is a guess) is that it will turn off the condensing fan when the compressor discharge line is cool during heating mode. I based this guess on the fact that one leg of the condensing fan passes through the circuit board.


Since the circuit board is not available, I am thinking about getting another brand's board or a generic board and using that instead.

My questions about doing that are:
Since the purpose of the two sensors are a mystery, what sensor(s) should I add to properly operate and protect the system?

Would the one called "Vent Sensor" be adequate to act as a defrost thermostat with a new board?

Also, do any of you know what the two sensors mentioned above are for?

A photo of the board is attached just in case one of you all recognizes it as a brand name in disguise.

Thank You for your help & advice!
Paul
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Old 05-10-2019, 02:15 PM   #2
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Re: Heat Pump Diagnosis & Defrost Board Replacement Question


the board shuts the condenser fan during defrost cycles so the outdoor coil can warm up fast and melt the ice.

it sounds like this unit has a demand defrost system which can sense when the coil is iced up.

can't find the model on the net.
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Old 05-10-2019, 03:27 PM   #3
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Re: Heat Pump Diagnosis & Defrost Board Replacement Question


https://appliancejim.com/vb551005

https://www.appliancefactoryparts.co...hr30c1var.html
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Old 05-10-2019, 07:17 PM   #4
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Re: Heat Pump Diagnosis & Defrost Board Replacement Question


The defrost board should not be "defrosting" while in cooling mode. that function is for heating only.

if you don't do an OE replacement, I like the white rogers/Emerson 47D01U-843 Universal Heat Pump Defrost Control. lets you set up for demand or timer based defrost.
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Old 05-11-2019, 07:26 AM   #5
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Re: Heat Pump Diagnosis & Defrost Board Replacement Question


Thank You All for helping.
Those sensor names sure are misleading! "Pipe Sensor" senses the coil & "Vent Sensor" senses the discharge pipe. (On one schematic it's called "Suction Sensor", but it's on the compressor discharge pipe. Oh Boy!)

I've been bench testing the board with interesting results.
(I can;t bring the sensors inside for testing, as they are brazed to refrigerant tubing.)

Shorting the HPS/LPS connector was required, as expected.
Shorting the Vent Sensor makes the board throw an error code "Vent Suction Sensor Short Circuit".
Shorting or leaving the Pipe Sensor connector open gives a code of "Pipe Sensor Open Or Short Circuit". That makes me fairly certain that this sensor is a thermistor. The colder the condenser coil gets, the higher the resistance. I checked it this morning at 38-F outside. The resistance was, indeed, higher than it was yesterday at 55-F and when heated with warm air.

It's interesting that originally, while still in the unit, I got no Error Codes. On the bench, I received codes.

On The Bench Results:
LPS/HPS = Shorted
Vent Sensor Connector = Open
Pipe Sensor = 4700 Ohm resistor across the pins.
Operation = Normal Operation

Next-
As soon as I can, I'll re-install it in the unit, leaving the resistor in place.
I'll add back one sensor at a time until the system fails.

I think the Vent Sensor (senses compressor discharge) might be the culprit.
Or, it is entirely possible that the discharge temperature is high, which is a project in itself.

Thank You User_12345a for the explanation of the board's function for defrost.
I see the outdoor fan (CFM in cooling) passes one leg through the board, but didn't know what controls it.

Thank You 6t7gto for the links. The Appliance Jim was a link to eBay. The board turned out to be, I think, I think it is for their companion indoor unit. Appliance Factory Parts said they might not be able to get the board & will let me know next week. (That board is different, but should work.)

Thanks u3b3rg33k for the name of the White Rodgers/Emerson universal board. That may prove helpful if the board is bad. I may even go with it if the sensors are bad since I can know the value of the sensors the universal board needs.

Plan B- Gut the controls and make the unit Cooling Only, adding compressor protection, low ambient shut off, etc as needed.
Having heat pump mode available is nice for if the boiler ever fails on a moderate day. Our 22 cents per Kw makes heat pump too expensive to operate day-to-day.

May I Ask A Couple More Questions?
In case the sensor is bad, what temperature does a Compressor Discharge Pipe Sensor usually open at (R-22)?

Is it possible that the sensor on the outdoor coil not only sense ice, as user_12345a mentioned, but terminate defrost as well?

Thanks Again for Helping!
Paul
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Old 05-11-2019, 10:29 AM   #6
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Re: Heat Pump Diagnosis & Defrost Board Replacement Question


The thermisters may be okay - i wouldn't rush to change them.

Need to find a manual with sequence of operation to troubleshoot this properly.

A regular time/temp based defrost board will not work. I'm unsure if even a universal demand defrost board will work.
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Old 05-11-2019, 02:59 PM   #7
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Re: Heat Pump Diagnosis & Defrost Board Replacement Question


Quote:
Originally Posted by user_12345a View Post
The thermisters may be okay - i wouldn't rush to change them.

Need to find a manual with sequence of operation to troubleshoot this properly.

A regular time/temp based defrost board will not work. I'm unsure if even a universal demand defrost board will work.
the universal one I mentioned comes with sensors - also lists what they are in the manual. no need to worry about what's already there. OP FYI, many heat pump units default to heat if the board fails, because it's better to have accidental heat than AC only if it fails in the winter. depends on how the reversing valve is set up. keep that in mind if you decide to re-design it.
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Old 05-12-2019, 10:29 AM   #8
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Re: Heat Pump Diagnosis & Defrost Board Replacement Question


Thanks Again Guys! I appreciate the help & education.

Need to find a manual with sequence of operation to troubleshoot this properly.

Unfortunately Haier's Service Manual is mute on the subject. Their tech support said they have no further information.

I do have a few questions about the Universal Replacement you mentioned UB3RG33K:

A) Do you know if the contacts for the Outdoor Fan are isolated ("Dry") contacts?
---------------------
B) The propaganda sheet says it has "Reversing Valve Shift Delay - Limits noise in and out of defrost cycle. Selectable 0, 12, 30 second delay"

What does this mean in operation? Does it somehow slow the de-energizing of the reversing valve's solenoid?
This would be great if I can somehow use the delay in cooling since my reversing valve screams quite loudly at the end of a cooling call. (Makes the neighbors crabby)
The fast opening valve is great for fast equalizing of pressures, but quite noisy!
-----------------------
C) Also, the wiring diagram (attached) show one leg of the terminals to the contactor coil shares with the Compressor Run Winding, the Run Capacitor & the Outdoor Fan Motor Run terminal. How can this be?

It also shows the line voltage from the motors as grounded. (Right side of the drawing, under a mounting screw tab) And one leg of the coil is grounded on the left side of the drawing.

This has me quite confused.
Drawn like shown, it would mean the contactor coil is line voltage or the motors are low voltage. Of course, neither is the case. (Also note that there isn't a Line In to the board.) And, 240 volt motors don't have a grounded leg.

My initial reaction is that the diagram is incorrect. But I may simply be reading it wrong.

My plan would be to send the "CC" terminals from the board to the existing 24 volt compressor/outdoor fan contactor coil.
I'd pass one leg of the outdoor fan through the contacts on the board for defrost (assuming they are dry contacts).

Does my interpretation of the wiring make sense?

Thanks Again!
Paul
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Last edited by Bird Doo Head; 05-12-2019 at 10:31 AM. Reason: I Type As Crummy As I Spell
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Old 05-12-2019, 11:58 AM   #9
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Re: Heat Pump Diagnosis & Defrost Board Replacement Question


The diagram does not look right at all.

I think the shift delay shuts the compressor and waits before switching the reversing valve when coming in and out of defrost.

Doubt it does anything for cooling.

Though the universal board manual should explain sequence of operation.
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Old 05-12-2019, 04:25 PM   #10
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Re: Heat Pump Diagnosis & Defrost Board Replacement Question


Quick question.


How did you bypass the indoor unit completely. Since it provides the 24 volts to the defrost board of the outdoor unit.


Also, are the DIP switches set up properly for your unit.


Is the CT wrapped twice for your unit.
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Old 05-13-2019, 08:03 AM   #11
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Re: Heat Pump Diagnosis & Defrost Board Replacement Question


Thanks All For Helping!

How did you bypass the indoor unit completely. Since it provides the 24 volts to the defrost board of the outdoor unit.
Also, are the DIP switches set up properly for your unit.
Is the CT wrapped twice for your unit.


Thanks Been There for these helpful verification questions.
To bypass the indoor unit, I removed the wires from the thermostat and the 24 volt incoming power at R & C. Next, I made up a test transformer with a fast blow fuse for R + C. Jumpers were available to simulate heat/cool calls, using Y and/or O. Plus...

The sensors and HPS/LPS are not removable without evacuating the charge, so when the board was on the bench:
For the LPS/HPS, jumping the board's connector out was sufficient.
For the compressor discharge pipe sensor (Called Vent Sensor), leaving it open was the answer to allow bench testing.
The outdoor coil sensor (called Pipe Sensor) a 4700 Ohm resistor was used across the terminals because that was the resistance I measured when the sensor was at 65-F outside.

The DIP Switch is as the manual wishes and the CT has the compressor line wire wrapped twice. None of these got changed this year, so they are as-was since when this was installed.

The diagram does not look right at all.
I'm glad to hear your comment, User_12345a!
As I age, the 'switches' in my brain have lots of glitches, but I was sure I could still read simple wiring diagrams & schematics. This one had me concerned about my old-guy cognitive skill decline.

That board has had a lot of quirks since the first time I ever saw it.
Whether they are defects or simply goofs when the manufacturer wrote the diagram or programmed the SMD is not known.

One is that the chart shows a code for "Solid LED On = Power Applied To R + C". In real life, the LED only illuminates when 24 is applied to the Y terminal and also still present at R + C.

The chart also shows an LED Flash code for HPS/LPS Open. When either one is open (they are in series), no code is ever generated. The compressor contactor is de-energized after FIVE minutes, and after 3 minutes, the compressor is allowed to re-start and run for 5 more minutes- even if the HP or LP condition remains.

I sure don't like this feature, as it would make for quite a project if there were a suction side leak someday!.

And, codes are often 5-10 minute delayed after any event.
Such Is Life With Electronics!

My next step will be, with the board re-installed and all sensors connected, remove the 24 volt source from inside and the thermostat wiring from the board. Then I will set up a temporary test transformer and Heat/Cool call test jumpers.
This way I can be 100% certain that the fault is not coming from the indoor unit.
When it fails, if no code is generated, I'll have to bypass each sensor one at a time- as when bench testing. Hopefully I'll find the culprit or cause (paying close attention to system pressures, outdoor coil temperature and discharge line temperature).

I think, but am nor sure, the board is a clone of GE WJ26X24064. But, if the board is bad, I'll go with the one suggested by u3b3rg33k. That way, I'll know all sensor specifications and have control over some features.

Unfortunately, I've been called away for an unknown time, so I have to temporarily leave the project. I'm quite interested to go back to it and track down the cause. (And report back here).

Thanks Again All!
Paul

Last edited by Bird Doo Head; 05-13-2019 at 08:12 AM. Reason: Edited because it is way easier to read if I actually complete sentences!
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Old 05-13-2019, 11:03 AM   #12
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Re: Heat Pump Diagnosis & Defrost Board Replacement Question


If that diagram is for the oem board i'm not surprised considering it's a chinese haier unit - probably used the cheapest unqualified labour, to do the literature.
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Old 05-13-2019, 04:10 PM   #13
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Re: Heat Pump Diagnosis & Defrost Board Replacement Question


It's the diagram for the Universal Board.

But, as you can see from the odd sensor names, the Haier diagram isn't all that perfect, either.

For fun I wrote to Emerson (They own White Rodgers) to ask about the shown wiring diagram. It will be interesting to find out if I get a useful answer (which I will share here).
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Old 05-13-2019, 07:17 PM   #14
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Re: Heat Pump Diagnosis & Defrost Board Replacement Question


Your defrost board only shows codes while the unit is running.
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Unread Today, 02:45 PM   #15
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Re: Heat Pump Diagnosis & Defrost Board Replacement Question


Your defrost board only shows codes while the unit is running.
Thanks for that mention! I thought something was wrong with the board because the LED-Off situation didn't match the Diagnostic Chart or manual.

What you said is exactly how the board is acting, as opposed to the Haier Diagnostic Chart and manual which say the LED is illuminated whenever power is at the 24-volt terminals (R & Common). Chinese translation problem, I'd imagine.

I'm curious about the temperature sensor on the Universal Board. After reading all the Universal Board literature from White Rodgers, it appears that the outdoor ambient temperature sensor is used in conjunction with the coil temperature sensor in the Defrost mode.

Do you guys know if that sensor also keeps the unit from operating the compressor (heat or cool) in low ambients, such as below 30-F ? Mine has that feature, but I don't know if this Universal Board does the same.

That's just a curiosity, as a generic ambient sensor is easily added in series with a leg of the contactor coil.

I also wonder what the reason for the Haier sensor on the discharge pipe of the compressor. I've seen discharge temperature sensors, tied to the alarm circuit, on chillers, but never saw one on a small unit. Is it necessary on a residential heat pump?

I am anxious to get back so I can work on this and track down the problem. (Was called away a few days ago.)

Thanks Again For Helping & Enjoy This Day!
Paul

Last edited by Bird Doo Head; Today at 02:49 PM. Reason: I Spel Verry Crummie And Have To Fix My MesUps
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