IV–102P23 Water Heat Exchanger Unit Interlock Error (for only water heat exchanger unit)c Error detection methodAn error is detected when the following conditions are met:• After a hot and cold water pump operation command, when the hot and cold water pump interlock signal (novoltage, a contact) is not ON within 5 minutes.• When the hot and cold water pump interlock signal turned ON once, but turned OFF again while the hot andcold water pump operation signal continued.d Troubleshooting1Water heatexchangerunit’selectricalbox1-1Is the hot/cold water pump operation command wiringconnected to the auxiliary hot/cold water pump electricalrelay? (Notes 1, 3)Yes 1-2No Request equipmentwiring1-2 Is a hot/cold water pump interlock connected? (Notes 2, 3)Yes 1-3No Request equipmentwiring1-3 Are any signal lines severed, faulty or short-circuited? Yes RepairNo 1-41-4 Is the power to the auxiliary equipment’s control boardswitched off?Yes Switch on the powerNo 1-51-5Is there any chattering in auxiliary equipment’s hot/cold waterpump electrical relay or in the hot/cold water flow switch?(Note 4)Yes Request equipmentrepairNo Replace the water heatexchanger unit boardNote 1: Hot/cold water pump operation command TB3: between No. 1 and No. 2 (No voltage a contact output)Note 2: Hot/cold water pump interlock TB4: between No. 1 and No. 2 (No voltage a contact input)Note 3: Operations are possible when there is a short-circuit between No. 3 and No. 4 on the TB3 terminalboard, but this may lead to the coolant freezing or other problems owing to a reduced flow volume, soan interlock must be connected without fail.Note 4: Switch on the flow switch to confirm that the correct flow volume is being maintained in series with thesignals operated by the coolant pump. Check the settings for the flow switch.● See “5. Reference Document” for details on the procedure for replacing the water heat exchanger unit’scontrol board.
