Absent parent/ paying for things

My sons dad has not been an active dad even when we lived together he called him by his first name, he moved back out and is off living his best life yet again but I’ve finally gotten a spot at the day care of my preference but it’s a bit outta budget, we still occasionally communicate about things other than my child (he doesn’t bring him up) I’m perfectly fine him fdoing his own things not being involved but I cannot do this alone. I’m a single parent recently divorced from my daughter’s father who is very active and helps where he can. Should I ask my son’s dad to at the bare minimum help with the day care cost? I have him 24/7 my other child 50/50 I’m having trouble maintaining work and really need the preschool/child care.