Arrived at a job today and found the isolator had been turned off by the customer, after turning it on the indoor unit started working so i went outside and after a few minutes the outdoor fan started shortly after i heard a crackle and a bad electrical burning smell i quickly turned the unit off at the circuit breaker & isolator, i then proceeded to open up the unit to find that a coil had been fried inside leaving alot of soot inside. Having never worked with these units i don't exactly know what that coil does, but it has 2 wires going to the pcb and the others are the A +N. The N looks pretty burned and so does that whole half of the coil.

The compressor, soft starter & start cap had been replaced 1 1/2 years prior to my visit and the unit had been working fine untill now.

Didn't have a megger on me but i tested resistence of the compressor windings with a multimeter and got 4, 1 & 5 Ohm which seems normal.

I'm guessing this coil has something to do with the compressor as the burning smell happened as soon as the compressor was supposed to kick in.

Is it worth finding a replacement coil or is it best to replace all coils and the PCB as well?

Anyone have any ideas?