s-10 blazer heater fan

I have a 2000 s10 Blazer.The heat blowes usually in the mourning but coming home at night no fan.I allready replaced the relay.Any ideas?

Manual or automatic climate control?
When the blower works, do all 4 speeds work?
When the blower acts up, do all 4 speeds quit?

Manual or automatic climate control?
When the blower works, do all 4 speeds work?
When the blower acts up, do all 4 speeds quit?
Whats the difference between manual and automatic? How do you tell?

It has dial low to high and an auto setting.Either every speed works or none work.

You have automatic climate control, that system is quite complex and requires a body capable scan tool to acurately diganose the system. You can check the blower motor, the blower motor feed wire and the blower motor ground wire connections. If those are OK, you'll need the scan tool.