Volvo: No heat

Question
2002 S60 non turbo

Fan works , AC works, temp gauge rides in middle, but I have no heat

Before I change out the heater core, I wanted to make sure to properly diagnose it

Could it be coolant level or t stat?

Thank you
Dwayne

Answer
I would run your vehicle to operating temp and then check the in and out hose that goes to the firewall.They should be about the same temp ,if not you may have a clogged heater core .If this is ok then i would look into the temp dampners that control the flp doors inside the box but it would be unlikely for both sides not to work .Hope this helps ,if possible use a infa red heat probe ..later rob .