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Samsung RC090MHXEA Service Manual Download Page 23

 

www.freedomhp.co.uk

 ©G Hendra Nov 18 

 

23

E251, Temperature Sensors 

 
E251

 is an error with the compressor discharge pipe sensor. It’s 

the blue sensor on the pipe leaving the compressor. It’s 
connected to the main PCB in connector at the top right of the 
PCB called CN43 in a white and red plug; it’s the 3

rd

 and 4

th

 wire 

from the top.  

 

 

 

 

 

 

 

 

 

 

 

 

To read what this sensor is 
measuring you can ask the unit 
using the interrogation function 
on the outdoor unit main PCB  

At the bottom of the main PCB 
are 4 buttons, you need to press 
K4 5 times. 

The display will show 05 XX, the XX will be the temperature this 
sensor is measuring; this sensor measures the compressor gas 
temperature you will need to compare the pipe temperature with 
the reading, if they are different the sensor needs replacing. 

Note: 

If this temperature is very high (over 80C) it 
usually indicates there are refrigerant 
problems, you will need to do a capacity test 
in HW mode. 

 

Summary of Contents for RC090MHXEA

Page 1: ... heat pumps from 2010 2015 Its all the work of Freedom Heat Pumps if you like it and would like a version for the current units you need to come on service partner training click here https www freedomhp co uk training Samsung Eco Heating System 2010 15 Service Manual Model Numbers RC090MHXEA and RC160MHXEA ...

Page 2: ...front of the remote controller slide it upwards turn it over DON T TOUCH THE PCB there are 8 dip switches near the red sensor using a small screwdriver flick dip switch 1 and 5 to on Cooling will no longer be available and test run will be activated Put the controller back on the wall ...

Page 3: ...Weekly button Run the Hybrid Boiler B4 live press the Set button Open the Hot Water Zone Valve B8 live press the Lock Button Open valve for heating Zone 1 B12 live press the DHW on off button Open valve for heating Zone 2 B16 live press the Mode button DHW Show 5 temperature sensor values in order press the View button Return temperature Flow temperature From heat pump Flow temperature From hybrid...

Page 4: ... relays When lit Led 500 immersion heater A4 live Led 501 backup heater stage 1 B2 live Led 502 backup heater stage 2 B3 live Led 503 backup boiler hybrid B4 live Led 504 pump running B6 live Led 505 Hot water valve open B10 Live Led 506 Zone valve 1 closed B14 off Led 507 zone valve 2 closed B18 off ...

Page 5: ... T S1 in the diagram below If the delta T temp difference across T S1 and T S2 is 5 degrees C the unit is happy this is its main control feature If T S 2 flow is less than 5 c above T S1 return the unit is providing too much heat so the compressor will slow down reducing capacity If T S 2 flow is more than 5 C above T S1 return the unit needs to work harder so it will rev up ...

Page 6: ...nit PCB you can run the units in test modes Normal display Is flashing between AdFO 0000 Button K3 resets the unit it s a quick way of resetting the power By pressing button K4 you enter the service mode here you can monitor the units operation Note there are 16 pieces of data one for each time you press the button K4 to exit press K3 ...

Page 7: ...e the heat pump is ok Now we have to make some more tests If its struggling to heat the house firstly take field setting 2091 and 2092 out of the system set them to 0 Now running the unit at a constant temperature test the unit at a 50C flow temperature If it can t make 50 C against the heat pump is probably not big enough To prove this if you close of half of the heating circuit you will see the ...

Page 8: ...d so it can t pull out Make sure the tank temperature is set to 48C on the remote controller press blue set button until the tap symbol appears and set it to 48C with the silver up button Press the blue view button you can see 4 sensor readings press it until the tap symbol shows This is the tank temperature It will display for about 10 seconds Using your own temperature probe test at the same poi...

Page 9: ...g the heater continues to operate once the temperature in 3044 is met When it goes wrong Legionella function only ends when the tank reaches the legionella set point If the immersion heater trips or is switched off the unit will gets locked in Legionella function It won t heat the house or the hot water cylinder How can I get the unit to heat if it is stuck in legionella To restart the heating you...

Page 10: ...mode is adjusted using setting 3025 For example if HW mode starts and setting 3025 is set to 30 minutes the hot water mode will end IF either the 30 mins is reached or the set point is reached whichever happens first Normally we set the max time to 60 mins for a 300L cylinder But beware if we are heating the cylinder we can t heat the house at the same time If the cylinder has completed a HW cycle...

Page 11: ...average bath is run at less than 41C The immersion heater in the cylinder can be controlled in 3 ways Using the std eco pwr button 2nd from top right the mode is changed When in eco mode 1 dot shows by the tap on the display in this mode only the heat pump heats the water the immersion is never used When in std mode 2 dots show by the tap on the display in this mode the heat pump heats the water f...

Page 12: ...ield setting 2091 not set to1 etc There are towel rads keeping the unit running all year long Does the unit stop when you turn all your thermostats off With AU on the screen the unit should only heat is a run signal is sent into terminals B22 or B24 on the unit Switch off the thermostats and carry out the tests on page 2 Hot water The tank stat is too low in the cylinder so the immersion is on all...

Page 13: ... With 2 showing press set grey press up or down until the tap symbol shows at the top of the screen with 2 dots press set adjust hours with up or down button to 6 am press set minutes flash press set Now everything flashes press set grey No3 appears After everything is set no 3 will show Press cancel delete twice the normal screen will show Daily will appear next to the time The timer is active To...

Page 14: ... curves you can just use one in the field settings as per the diagram above You must activate the stats using setting 2091 to activate terminal 22 and 2092 to activate terminal 24 When you make the connection 20 22 on the control box the unit uses the blue curve and lets water flow into the system valve 1 connected to 11 and 14 will be open When you make connection 20 24 the red curve higher temp ...

Page 15: ...n you can see 4 sensor readings press it until the pump symbol shows a circle round a house This is the water temperature if it s below 10C the unit will not start but the pump will run If you are commissioning the unit from cold You must warm up the water to get the unit to run the easiest way to do this is to add a cylinder and use the immersion to warm up the cylinder first the warm water from ...

Page 16: ...ont cover removed All measurements taken 300mm from the service valves with S3 sound meter Note these readings do not relate to the figures given in proper sound testing carried out by Samsung in Anechoic chambers with covers on at 1m The figures should be used for reference purposes only Note how the unit is noisier as it starts and then settles into a fairly steady increase in dB as it speeds up...

Page 17: ...ate the sensor in the remote controller this can but don t be used to control the unit using the Samsung controller as a room stat In this mode the unit runs in weather comp both as a function of outdoor temperature see weather comp and as it gets close to the set temperature the unit also drops the flow temperature Switch 3 if set to 1 brings up a fault code E121 If switch 4 is set to 1 the contr...

Page 18: ...er up the indoor unit note how if you ask it for the flow temperature it shows 50C this is because the indoor can t see the flow sensor which is in the outdoor unit Note also that the unit thinks its 0C outside again the indoor unit can t see the outdoor sensor After about 5 mins everything will sort itself out In the mean time you will see E201 error on the indoor remote and E202 on the outdoor u...

Page 19: ...e across the pins on the board If the Voltage across the pins is between 270mV and 300mV and fluctuating the outdoor PCB is fine and you need to look at the cables between the indoor and outdoor PBC s There is a terminal block on the outdoor unit below the PCB labelled F1 and F2 this is where the communication cables between the two units are wired into if the voltage reading across F1 and F2 here...

Page 20: ...n operating correctly the inverter PCB should have 3 leds showing the red one at the front will be on the green one below it will be flashing and a green led in the middle of the board will be lit If not the PCB is faulty When the comms is faulty or the pcb is broken the red led at the front will be on the green one below it will NOT be flashing and a green led in the middle of the board will be l...

Page 21: ...s the bottom two wires To read what this sensor is measuring you can ask the unit using the interrogation function on the outdoor unit main PCB At the bottom of the main PCB are 4 buttons you need to press K4 4 times The display will show 04 XX The XX will be the temperature this sensor is measuring this sensor measures the air temperature at the back of the outdoor unit you will need to compare t...

Page 22: ...uttons you need to press K4 7 times The display will show 07 XX The XX will be the temperature this sensor is measuring this sensor measures the refrigerant temperature at the bottom of the big blue coil on the back of the outdoor unit it s clipped to the coil you need to remove the back cover to get to it You will need to compare the coil temperature with the reading if they are different the sen...

Page 23: ...asuring you can ask the unit using the interrogation function on the outdoor unit main PCB At the bottom of the main PCB are 4 buttons you need to press K4 5 times The display will show 05 XX the XX will be the temperature this sensor is measuring this sensor measures the compressor gas temperature you will need to compare the pipe temperature with the reading if they are different the sensor need...

Page 24: ... s the top 2 wires Its not possible to test this sensor using the inbuilt check functions you need to test it with a multi meter Details of how to do this are at the end of this chapter E320 happens when the circuit is open sensor damaged or not plugged in correctly Or if the compressor temperature is super cold below 2C this error is not a shortage of refrigerant or overheating problem The sensor...

Page 25: ...ssor refuses to kick in because the temperature outside AND inside is too cold it all comes down to where the remote controller is located If located in an unheated space you ll find this fault You ll also find this fault if you have left the power off to the outdoor unit in cold weather for a long period of time ...

Page 26: ...oor unit in the first 60 seconds If so the HP switch is faulty Call Freedom HP for advice the HP switch will need to be replaced See below Installing the HP switch Turn off power to outdoor unit remove front cover On front of unit there are 2 service valves they are brass Remove the front cover from the left hand valve and check the valve is tight using a 4mm Allen key clockwise Using a spanner re...

Page 27: ... T reset the power Now start the unit up does it now work If so the valve was stuck It s a very good idea to replace the outdoor unit pcb When the new PCB is to be installed with the unit operating kill the power gently tighten the valve head don t over tighten it use had tightness only Now kill the power and replace the PCB with the new one restart the unit Test 3 If the unit starts up the compre...

Page 28: ...heck if the sensor is place where it could be exposed to higher temperatures If everything looks normal with the sensor then it could be faulty E441 This is the reverse of E440 This error occurs when the unit is in cooling mode and is being asked to cool when the temperature is below 5C It is even more unlikely that this fault would appear as the units should have the cooling function disabled at ...

Page 29: ...ly DO this with the power off once the power is off wait for 60 seconds and make sure all the LEDs are off The plug can be found on the front of the inverter PCB and is white with 6 wires in it Even though the size 9 only has 1 fan there are still 2 sockets the fan motor plug should plugged into the bottom socket if it is not plugged in or plugged into the upper socket this will be the cause of th...

Page 30: ...This would point towards a communication error between the indoor and outdoor unit The fault is actually caused by the small PCB circled on the front of the main PCB in the outdoor unit being loose To fix the problem turn the power off and make sure the PCB is properly attached by carefully pressing it until there is a small click E461 and E462 Over current detected in inverter See E467 ...

Page 31: ...operation continues for long periods the unit will be damaged Eventually you will see E464 error The reason for the whooshing is simple it happens when the water returning to the unit is not significantly lower in temperature than the flow in other words no heat is being rejected in the house Is the compressor faulty Likely if the unit has been running for ages in condition above Please note that ...

Page 32: ...cb 16kW Set your meter to Ohms put the red lead on P shown and measure the resistance to each of the 3 compressor terminals the reading should be the same on all 3 terminals it should be above 2M Ohms If any readings are low below 500kQOhms the inverter is broken ...

Page 33: ...cb 16kW Set your meter to Ohms put the red lead on N shown and measure the resistance to each of the 3 compressor terminals the reading should be the same on all 3 terminals it should be above 2M Ohms If any readings are low below 500kQOhms the inverter is broken ...

Page 34: ...18 34 Testing the inverter pcb 9kW Set your meter to Ohms put the red lead on the diode shown and measure the resistance to each of the 3 compressor terminals the reading should be the same on all 3 terminals it should be above 4M Ohms ...

Page 35: ...35 Testing the inverter pcb 9kW Set your meter to Ohms put the red lead on the solder blob shown and measure the resistance to each of the 3 compressor terminals the reading should be the same on all 3 terminals it should be above 4M Ohms ...

Page 36: ...is the reverse of removal but put more white paste comes with the new PCB on the cooling fins first make sure tighten all 4 screws When you plug the board back in leave the fan motors and the compressor disconnected Power up the unit and check the 3 leds light on the front light up if they do turn off the power wait 40 seconds and plug the compressor in and try again if all is ok now power off and...

Page 37: ... wires and 2 white wires You must check they are all plugged into the inverter pcb If they are un plug the reactor and test the resistance of the reactor it should be 0 ohms across the two black wires and 0 ohms across the 2 white wires Reactors NEVER go wrong We had one unit size RD160 with this fault which was caused by the inverter pcb being faulty new pcb and it works Just had an rc090mhxea un...

Page 38: ... after 60 seconds all the lights will go out DON T TOUCH anything until this happens Now remove the electrics cover from the top of the compressor using a spanner and after making a note of where the wires go disconnect them Test 1 Using a meter measure the resistance of the compressor windings to do this set your meter to the ohms or Ω setting put one lead of the meter on one compressor terminal ...

Page 39: ...sure all the LEDs are off Once the plug is properly connected to the inverter board the fault should clear If a size 16 main outdoor PCB is put into a size 9 outdoor units you will see this error It s because a 9 kW is programmed to have 1 fan motor The symptoms of the fault will be the same but the error will not clear when the both the plugs are connected to the inverter board correctly The only...

Page 40: ...ill see E500 Tighten the screws put heat paste under the chip s and check the fan motor top runs when the compressor is running E554 Gas leak error The unit has detected that there is no rise in compressor discharge temperature despite the compressor operating this means there is a refrigerant error Carry out test on page 6 Fault code E601 see E604 ...

Page 41: ...he unit If you hold the remote controller with the red sensor at the top from factory all of them are switched off Down Switch 1 is on the left if switch 4 is set to on or up the controller will not start up properly all that will be seen is some flashing lines going in a circle under schedule and will show E602 error after 5 mins ...

Page 42: ...2 is brown and V1 is orange The cable plugs into the back of the PCB using a white plug it only fits in one place The plug is on the right hand side half way down the board if you are holding the controller with the red sensor at the top If the remote controller is not connected properly the red flashing LED 900 in the middle of the control box PCB will not flash Wire V1 is 12Vdc wire V2 is 0V DC ...

Page 43: ...t be unplugged for testing so with the power on press the blue set button until a house symbol appears with a thermometer by it this is measuring the temperature at the remote controller If the reading is not realistic the whole remote controller needs changing All is not bad news the unit will continue to work perfectly with this fault showing ...

Page 44: ...he test mode from the remote controller inside To access TEST mode press blue set button and test button together for 6 seconds The controller will display TEST Press the blue view button once a temperature will be displayed and the word IN shows This is the reading from the sensor If you compare this with the actual water return temperature it should be exactly the same If they are different the ...

Page 45: ...the test mode from the remote controller inside To access TEST mode press blue set button and test button together for 6 seconds The controller will display TEST Press the blue view button twice a temperature will be displayed and the word OUT1 shows This is the reading from the sensor If you compare this with the actual water flow temperature it should be exactly the same If they are different th...

Page 46: ...emperature available from the system If you have this fault but don t have a backup heater then reset field setting 4021 back to 0 Hybrid systems do not use this sensor You can view this sensor in the test mode from the remote controller inside To access TEST mode press blue set button and test button together for 6 seconds The controller will display TEST Press the blue view button twice a temper...

Page 47: ...t has a tank To test this sensor press the blue set button until the tap icon appears this will show the temperature its measuring if this reading differs from the tank temperature the sensor will need replacing NOTE The tank sensor has a yellow plug which goes into a yellow socket on the control PCB It is possible to put it in the red plug on the PCB this will not work Wrong Correct ...

Page 48: ...n valve sensor It s connected to a yellow plug on the bottom right of the main PCB connector CN44 in a yellow plug it s the bottom two wires This sensor is red it s clipped to the refrigerant pipe under the white switch box It is not possible to test this sensor unless you use a meter this can be seen at the end of this chapter ...

Page 49: ...esponds to But it s still worth checking to see if the sensor is at fault before changing it All you ll need is a temperature probe and a multi meter Using the K4 button on the outdoor unit you can check what almost all the sensors in the outdoor units are reading if your probe s reading is massively different to what the unit is reading you have a problem If the sensor that you re looking for has...

Page 50: ... CN44 yellow plug blue sensor for outdoor unit heat exchanger inlet Return Top sensor of this plug Wire 1 and 2 Number 7 in the K4 menu E902 CN44 yellow plug blue sensor for outdoor unit heat exchanger Flow outlet Middle sensor of this plug Wire 3 and 4 This sensor can be viewed from the indoor unit using the view button E221 CN43 white plug red sensor for ambient air Back of the unit The bottom s...

Page 51: ...mode to run it permanently clear the air and when finished begin the commissioning process We have found that getting the air out of the system is difficult normal auto air vents don t seem to work as the water speed is high We recommend using a de aerator Spiro vent do one The flow switch too close to a pump bend or valve the flow switch should be at least 150mm from any other fitting The flow sw...

Page 52: ...low meter should be 0 If it s not going looking for other pumps they are causing the problem If the pump continues to run check it s wired live to B6 and N to B7 If this is correct the PCB is faulty In a few cases there has been a problem with the flow switch causing an E912 To test if the flow switch has a problem you need to make sure that the power to the unit is off and there is no flow Remove...

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