1998 P-38 heater issue
 

Aside from my 2008 l322 I also have a 1998 P-38 I have had for about 15 years now. Motor has been replaced due to a deranged mechanic screwing it up. I also had a new heater core installed about 3 years ago and the heater was fine until recently. My daughter took the truck to a car wash and claims all she did was steam clean my motor inside and underneath. Now, not much heat. I cannot find a leak and you can get some warm air but I am fresh out of ideas on this. Any insight into what it could be. No coolant loss either.

thanks