So got a s40 guy couldnt get it to run and he replaced the heater core and didnt put it back together... Im having a issue since its running and its 100 degrees outside and trying to get it put back to use the ac..
The black box the heater core is in I put back together but on the passenger side there is a 3 inch by 6 7 inch slit where you can see the heater core but its blowing out straight hot air.... Is there something that goes there? I have the parts all sitting out and cant figure it out for my life what goes there, also there is to screw holes on the left and right of it?
Anyone for info Pictures im trying to find some and came across this site...
Ty

 

volvos constantly run coolant through the heater core - there is no shut off valve. The car controls the heat to the cabin via airflow and "blend doors" that the HVAC controls. So if the dash is not assembled correctly, you will have a way for the heat to get from the core into the cabin. If the blend doors are not working properly - ie failed motors, rods not attached, doors out of sync, you will get warm air into the cabin, plus you will likely see a fault code for the ECC. (it may be a blinking AC/REC light etc...)

 

Is it where the cabin filter is supposed to go? There is a cover over it also - #18 and 19 on the parts page.