Have a carrier hh93az173a and installing a rth7500d unit is not cooling fan old unit has 8 wires on it

Guessing maybe you didn`y tag/label the wires as you removed them from the old tstat
The colors are not always put where the rule of thumb says they should go

Did a installers manual come with the honeywell?

http://customer.honeywell.com/techlit/pdf/PackedLit/69-2487ES.pdf