As Sun is functional benefic planet for Aries , Gemini , Cancer , Scorpio , Sagittarius ascendants , in 3rd house , Sun will give positive results unless it is afflicted with functional malefic planets for particular ascendants.
For Aries , Sun will help persons who wants to make there career in sports and it will give them enough strength and courage to pursuit there goals.
For Gemini , Sun will give enough courage , stamina and communication skills to finish of there personal and professional commitments on stronger note.
For Cancer , Sun will give better relations with brother and Sisters .
For Scorpio , 10th house lord Sun in 3rd house might leads to frequent travel in relation to his /her professional life and one might be in the profession , which involves lot of traveling .
For Sagittarius , 9th house lord Sun in 3rd house will involve traveling in relation to spirituality or in relation to family life . One will get sufficient support from his/her father too .
Sun will give average results for Taurus ,Aquarius ascendent natives.
For Taurus , 4th house lord , Sun in 3rd house might leads to stay away from his/her house which might be due to professional commitments .
For Aquarius , Sun in 3rd house might pull pressures in one marital life which might be due to lack of quality time for each other.
Sun will be malefic for Virgo , Libra , Capricorn and Pisces ascendent natives .
For Virgo , Sun might creates tensions between brother , sisters and father which might be due to money .
For Libra , One might had to work harder in order to gain from finances . Due to this , He/She might not able to enjoy his family life fully.
For Capricorn , Sun might pull pressures in one family and professional life .
For Pisces , Sun in 3rd house might give communication and concentration problems . Aggression might be more which might be bad for health .
Here , special emphasis had to be given Leo as Sun in 3rd house for Leo makes Sun , debilitated (weaker) and one had to put lot of efforts in his/her personal and professional life to get life moving for him/her in right direction.