Thank you @murtoz for your answer, it was very useful. I spent many hours playing and investigating more deeply on how IR codes works, and want to share some details that can help others.
I have two Broadlink IR remotes that works fine with these A/C. So I used the Broadlink Base64 code and decode it to HEX. So I could “read” the pulse timming and found that in my IR code has a LOW pulse (negative in RAW format) for 20ms. Reading again ESPHome Remote Receiver component docs, I’ve found the “Idle” configuration variable to set the timeout for a stable state of the signal. Default value is 10ms, setting it to 25ms give me the correct read from the IR Receiver, with only one “Received Raw” event!
My next problem was that if I send that negative value of “-20,000” microseconds (or 20ms) in the RAW format, an IR receiver read values of 4ms to 6ms of LOW pulse, not 20ms. Reading the source code I found that the ESPHome Remote Transmitter component works well with values below 16ms.
So I found a workarround replacing the original “-20,000” pulse with “-10,000, 1, -10,000”, and that works fine!
Today I’ve update HA to version 0.110, and now I can use SmartIR with ESPHome by using a custom service to send Raw IR Codes! 