I've just had the heater core replaced in my 99 blazer S10, everything works, blower, air direction, ac comes on too - but it blows hot air all the time. I've tried pulling the RDO a few times in order to reset the cold/hot air flap actuator but to no avail.

Could the mechanic have busted something in the dash or is there a plug somewhere he may not have re connected?

I know changing the heater cores on this SUV is a total nightmare of a job but that bit worked fine before it went in!

any help where to look would be great!