Water gets in his nose when he washes his face during wudu

Firstly: 

There is nothing wrong with you expelling the water that gets into your nose when you wash your face, after you have finished rinsing your mouth and nose. This is not regarded as something extra in addition to the three times that are mentioned in the Sunnah, because you did not deliberately make the water get into your nose. The scholars (may Allah have mercy on them) have stated that it is better when washing the face to start at the top, so perhaps if you do that, no water will get into your nose. 

Al-Nawawi (may Allah have mercy on him) said:  

Al-Maawardi said: The mustahabb manner of washing the face is to take the water in both hands, because that is more effective in making the water reach the whole face etc, and to start with the top of the face and move downwards, because the Messenger of Allah (peace and blessings of Allah be upon him) used to do that, and because the top of the face is more noble, as it is the place of prostration, and it is more effective as the water naturally runs downwards. Then he should pass his wet hands over his entire face so that he can make sure that the water reaches all the parts it is supposed to. But if he makes the water reach all parts of his face by any other method, that is sufficient. End quote. 

It also says in Mawaahib al-Jaleel (1/187), describing the manner of washing the face: He should start at the top. 

Secondly: 

The Sunnah indicates that one should snuff water up into the nose and expel it three times, as al-Bukhari (186) and Muslim (235) narrated from ‘Abd-Allah ibn Zayd that he demonstrated for them the wudu of the Prophet (peace and blessings of Allah be upon him): He rinsed his mouth and nose using one handful (of water), and he did that three times.  

This hadith indicates that the Sunnah is not to separate the rinsing of the mouth and nose, and to rinse both the mouth and nose from a single handful of water, then rinse the mouth and nose from a single handful, then rinse the mouth and nose from a single handful. This is unlike what many people do by separating them; they rinse the mouth three times then they rinse the nose three times.  

Al-Nawawi (may Allah have mercy on him) said in Sharh Muslim: 

Our companions said: However the water reaches the mouth and nose, this fulfils the aim of rinsing them. As to which way is better, there are five opinions, the first of which is that the mouth and nose should be rinsed with three handfuls of water, rinsing the mouth and then the nose each time… this method is the correct one, and is described in saheeh ahaadeeth in al-Bukhaari, Muslim and elsewhere. As for the hadith which indicates separating the two (actions), it is da’eef (weak). This leaves us with one correct way, of washing both the mouth and nose together with three handfuls, as we have indicated, because of the hadith of ‘Abd-Allah ibn Zayd which is quoted in the book. End quote. 

Rinsing them more than three times is makrooh. The evidence for that is the report narrated by al-Nasaa’i (140), Abu Dawood (135) and Ibn Maajah (422) from ‘Amr ibn Shu’ayb from his father from his grandfather, who said: a Bedouin came to the Prophet (peace and blessings of Allah be upon him)and asked him about wudu. He showed him how to do it washing each part of the body three times. Then he said: “This is wudu, and whoever does more than this has transgressed the limits and wronged himself.” 

This hadith was classed as saheeh by al-Albaani in Saheeh al-Nasaa’i. 

Al-Nawawi (may Allah have mercy on him) said: 

The scholars are unanimously agreed that it is makrooh to do that more than three times. What is meant is washing that part of the body thoroughly three times, but if on one of the times the part is not washed thoroughly and the washing has to be repeated, then those two times will count as one.  

If a person is uncertain as to whether he was washed two or three times, he should regard it as two and do it a third time. This is the correct view, as stated by the majority of our companions. Shaykh Abu Muhammad al-Juwayni, one of our companions, said: He should do that three times and no more than that, lest he commit an act of bid’ah by doing it four times. The fourth is bid’ah and is makrooh if he does it deliberately, and Allah knows best. 

The point is that there is no sin on you if you expel water that gets into your nose by mistake, and this is not regarded as doing something extra in wudu, because you are not doing it deliberately. 

And Allah knows best.