Version/revision of the library used

2.7.5

Expected behavior

Shut down my Samsung AC correctly

Actual behavior

@80MHz same code works well 100% of the time.
@160Mhz sometimes the AC is not turned off by this code.

  #include <IRremoteESP8266.h>
  #include <IRsend.h>
  #include <ir_Samsung.h>
...
acir.off();
acir.sendOff();     

Circuit diagram and hardware used (if applicable)

https://github.com/sblantipodi/smart_thermostat

I have followed the steps in the Troubleshooting Guide & read the FAQ

YES

Has this library/code previously worked as expected for you?

NO