I have an bad capacitor of 3.7uf with 3 wires,gray,blue and yellow,is it possible to replace it with a 3.5uf capacitoe with black and red wires.how do I connect the 3.5 to where I removed the 3.7uf

This forum is for electrical questions, not electronic design questions.

Regardless, we would need more information from you. For example, what is the "Effective" range you need for the cap? What type of circuit are you working on? Is it a ceiling fan?

There is an electronic forum on this site and I will see if I can get this post moved to that forum.