PANASONIC AIR CONDITION CS-S13SKH TURN OFF AFTER ON[SOLVED]

 Salam all, anyone having the same issue as me?

Mine have old panasonic air condition (AC) model CS-S13KKH inverter model [Fig 1]. Been used for many years..but suddenly wife reported that AC unit turn OFF by itself.

Fig 1: Indoor unit of Panasonic AC 1.5HP

Symptom?

Unit has been running for several hours before reported symptom. Try to restart the AC, resulted in having the same symptom again after several minutes. We tried ON the AC unit several times which then causing our 16A MCB circuit breaker in DB unit tripped.

Upon checking the circuit breaker unit, the breaker body is hot suggesting the AC unit drawing large amount of current. Return the breaker switch to ON again to test the AC unit, still resulted in breaker being tripping down (OFF) again. So, no more trying (a bit dangerous if MCB breaker keep trip which might be caused by short circuit) and, the system and their connection from supply to AC unit need to be troubleshoot and verify.

AC Unit Specification:

FYI, the AC unit got 1.5HP cooling capacity where rated current around 7.4 A. AC have split unit indoor and outdoor.

Common issue?

This model have common issue with the copper and coil sensor (Fig 2) that attached to the cooling fin on indoor unit. However, ther are also some other issue such as power supply pcb board, fan motor unit, and the low presure gas due to the leak.

Fig 2: Copper and coil sensor [pic from google]

What To Do?

Before knowing the real issue behind the problem,  troubleshooting work start with below steps:

1. Checking the main supply from distribution board (DB) and 16A circuit breaker (MCB) that connected to the AC unit. Fig 3 illustrates our home electrical system in single line diagram. While, Fig 4 shows  breaker arrangement in our DB. Main supply voltage is trace on the Main switch and ELCB as well MCB circuit breaker.

Fig 3: Single Line diagram for our home

Fig 4: Main switch, ELCB and MCB arrangement in DB

2. Supply from Main Switch and ELCB is measured and shows 241V voltage supply. Meaning no problem on these sides.

3. After that, input and output of the MCB 16A is evaluated. It is found that, once the MCB breaker is ON, the voltage reading on output side (reading from multimeter and are measured multiple times) is only around 12+V, indicating that there is an issue with this breaker. Normal working voltage on the output side of the MCB breaker should be the same as breaker input during ON state condition, which is around  240V as measured on Main switch and ELCB. 

So, this damaged MCB circuit breaker is taken out from DB and replaced with the new working MCB breaker. Fig 5 shows the damaged MCB breaker that are replaced by the new MCB from the DB. New MCB breaker are isnpect and measured 240V volatge output once its turning ON. New replaced MCB breaker are shown in Fig 4 above, on the top row, third MCB from the right

Fig 5: Damaged 16A MCB circuit breaker 

4. On the AC unit side, several work has been done such as taking out PCB unit of digital and power supply board to visually inspect the board condition. From the visual inspaection, no damaged are visible. Then all pcbs (shown in Fig 6, Fig 7 and Fig 8) are cleaned using the electrical and contact cleaner spray.

Fig 6: Power supply analog board

Fig 7: Digital pcb board

Fig 8: LED status pcb board

5. Meanwhile, as the coil and copper sensor part still on the way, old coil and copper sensor are taken out and clean using alcohol with the hope that it might solve the issue (as on Fig 2).

6. Indoor unit cooling fin are also cleaning out using chemical spray.

7. Then, everything are installed back before doing the run test.

Electrical Circuit Diagram for References:

Attached here the circuit layout for both indoor and outdoor AC unit. can be observed that, both Fig 9 and Fig 10 contained resistance measurement for motor unit, which can be use to check your motor condition on both indoor and outdoor unit. In our case, no testing require on the ac motor side, since the motor are perfectly fine.

Fig 9: AC indoor unit electrical diagram

Fig 10: AC outdoor unit electrical diagram

Replacement Parts?

Copper and coil sensor cost as much as RM15 on the online retail store. Upon realising this issue (although not 100% sure on this) are from the coil sensor, the part is ordered as a replacement sicne the cost is minimal (only RM11 including shipping from online store) and dont want to wait longer.

Outcome and discussion?

After all pcb and part are assemble back, we run the test to check the AC condition. When MCB breaker is put to ON condition, and the AC unit is turn ON using the remote, AC unit able to operate. AC unit is left running for 2 hours with normal setting (cool mode and 26 deg C) and current reading from supply to AC unit is monitored on the MCB breaker output.

The current reading after almost 2 hours run (temperature is stabilised and AC unit is working is steady state) are around 2.2-3A. Currnt reading just after compressor started is around 4.5A-6A. Thats mean, current draw by the AC unit is settled down after temperature reaching its desired level.

On the DB side, the broken MCB breaker, happened probably due to the dirty coil and copper sensor in the AC unit causing the AC unit not able to correctly read the temperature near the coil fin and room temperature. This caused the compressor unit to work harder that usual, leads to drawing large amount of current from the main supply in DB. We also notice that the coling coil fins are really wet, when we first discover this issue, which probably due to the icing condition on the cooling coil.

Taking the chances by cleaning the copper and coil sensor really help us, where our AC unit working flawlessly again. Although, RM11 are wasted when we purchased the part, but that part can be kept as a replacement, if the actually sensor get damage in the future.

Need service manual?

Please find below pdf link for service manual for this model. Hope this manual help

Link: http://gofile.me/5KhVk/RNwQmtTpP

Thanks a lot for reading this. Hope this help anyone having the same issue.