however if this would continue what should I do ?
I would think that depends on your definition of "hot" as to motor temp. Depending on the type of flying you are doing - a couple of motors may get slightly "warmer" than others (but not "hot").
If you are able to...........check the temps on all 4 motors after a flight (
near the bottom of the motor frame or where you notice higher temp by touch) just to see if the difference is appreciable.
Note: A motor that has increased temps (
due to working harder via increased load) is due to drawing more current (
when that happens it will convert the extra current/power/load into heat). So if the temp is appreciably high it is worth getting to the bottom of it and finding the cause and effect........(
well actually you know the effect now - which is heat).
An overheated motor will eventually burn the insulation off the windings and you will have shorted turns and/or motor seizure (which you clearly would not want while flying). Excessively high temps can also cause issues with motor magnet failure - but that's very hot (130'c - 140'c).
This can be a result of .. as mentioned bearing issues, shorted turns in the windings or an issue with the ESC for that motor (
electronic speed control).
It is also possible the issue is the ESC for that motor - did you happen to have a "tip over" that caused a prop to dig into the ground and stop the motor? That can cause ESC issues/failure.
If temps are very high at that motor and the motor looks and feels ok turning by hand, windings look ok etc. - a simple way to check if you have an ESC issue is to switch that motor to another arm on the Phantom (
make sure it is switched correctly with the same rotation of motor).
If the motor you switched is ok temp wise after a flight or perhaps just a very low altitude hover - and the motor you switched to the arm where the "
hot motor" was is now the one with the higher temp - then it is likely an ESC issue.
If you are worried about anything happening (
motor failure) while testing in a hover - just give the Phantom something "cushy" to land on - not saying this will happen at all.