Service And Maintenance; Basic Troubleshooting For Cylinder Unit - Mitsubishi Electric Ecodan EHST20 serie Para El Instalador

7

Service and Maintenance

The indoor cylinder unit is UNVENTED. Under UK law* the system must be
serviced once a year by a qualified individual. Servicing and maintenance of the
outdoor unit should only be done by a Mitsubishi Electric trained technician with
relevant qualifications and experience. Any electrical work should be done by a
tradesperson with the appropriate electrical qualifications. Any maintenance or

Basic troubleshooting for Cylinder Unit

no. Fault symptom
1 Main controller display 1. There is no power supply to main
is blank.
2. Power is supplied to main controller,
2 "Please Wait" remains 1. "Please Wait" is displayed for up to 6
displayed on the main
controller.
2. Communication failure between the main
3. Communication failure between FTC4
3 The main screen The main controller operations do not work
appears with a press for a whilst after the settings are changed in
of the "ON" button, but the service menu. This is because the system
disappears in a second. takes time to apply the changes.
4 LED2 on FTC4 is off. When LED1 on FTC4 is also off. (See <Figure
(See <Figure 5.2.1>.) 5.2.1>.)
<FTC4 powered via outdoor unit.>
1. The outdoor unit is not supplied at the
2. Defective outdoor controller circuit board.
3.
4. FTC4 failure.
5.
51
Possible cause
controller.
however, the display on the main
controller does not appear.
minutes.
controller and FTC4.
and outdoor unit.
rated voltage.
FTC4 is not supplied with 220 to 240V
AC.
Faulty connector wiring.
'DIY' fixes done by a non-accredited person could invalidate the Warranty and/or
result in damage to the cylinder unit and injury to the person.
* Building regulations – England & Wales Part G3, Scotland P3, Northern Ireland
P5. If outside of the UK please refer to local building regulations regarding un-
vented hot water storage.
explanation - Solution
1. Check LED2 on FTC4. (See <Figure 5.2.1>.)
(i) When LED2 is lit.
Check for damage or contact failure of the main controller wiring.
(ii) When LED2 is blinking.
Refer to No. 5 below.
(iii) When LED2 is not lit.
Refer to No. 4 below.
2. Check the following:
• Disconnection between the main controller cable and the FTC4 control board
• Failure of the main controller if "Please Wait" is not displayed.
• Refer to No. 2 below if "Please Wait" is displayed.
1. Normal operation.
2, 3. Main controller start up checks/procedure.
(i) If "0%" or "50-99%" is displayed below "Please Wait" there is a
communication error between the main controller and the FTC4 control
board.
• Check wiring connections on the main controller.
• Replace the main controller or the FTC4 control board.
(ii) If "1-49%" is displayed there is a communication error between the outdoor
unit's and FTC4's control boards.
• Check the wiring connections on the outdoor unit control board and the FTC4
control board.
(Ensure S1 and S2 are not cross-wired and S3 is securely wired with no
damage. (See section 4.6.)
• Replace the outdoor unit's and/or the FTC4's control boards.
Normal operation.
The indoor unit is applying updated settings made in the service menu. Normal
operation will start shortly.
1. Check the voltage across the terminals L and N or L3 and N on the outdoor
power board. (See section 4.6.)
• When the voltage is not 220 to 240V AC, check wiring of the outdoor unit and
of the breaker.
• When the voltage is at 220 to 240V AC, go to "2." below.
2. Check the voltage across the outdoor unit terminals S1 and S2. (See section
4.6.)
• When the voltage is not 220 to 240V AC, check the fuse on the outdoor
control board and check for faulty wiring.
• When the voltage is 220 to 240V AC, go to "3." below.
3. Check the voltage across the indoor unit terminals S1 and S2. (See section 4.6.)
• When the voltage is not 220 to 240V AC, check FTC4-outdoor unit wiring for
faults.
• When the voltage is 220 to 240V AC, go to "4." below.
4. Check the FTC4 control board.
• Check the fuse on FTC4 control board.
• Check for faulty wiring.
• If no problem found with the wiring, the FTC4 control board is faulty.
5. Check the connector wiring.
• When the connectors are wired incorrectly, re-wire the connectors referring to
below. (See section 4.6.)
L
N
FTC4 powered Black
CN01
via outdoor unit
S1
Cylinder unit
S2
control board
S3