Maybe use skillfuture go learn and DIY and also can do side hustle
https://www.myskillsfuture.gov.sg/content/portal/en/portal-search/portal-search.html?fq=Course_Supp_Period_To_1%3A[2025-09-09T00%3A00%3A00Z TO *]&fq=IsValid%3Atrue&q=Air Conditioning
mine everything is exposed, i dont even paint the trunking. everything in my home is modular, design to be replaced easily
the reason why i feel AC is not worth it to repair like pcb board spoil or any repair + servicing (combine together since once over $600 and over 4 yo, it cheaper to get a new one) a new 9k btu is 1.1k, 12k btu is 1.3k, 15k btu 1.6k and 18k btu is 1.9k
here the price of the pcb board if you get from starmex and replace yourself VS get aircon vendor to replace any they charge over $700 for pcb board and thermistor at least $150.