No heat could mean a clogged heater core or a failed thermostat. Get the Haynes repair manual for the Ram. It's not the best book in the world but it does have some good basic troubleshooting steps when certain symptoms are present for various vehicle maladies.

 

And since we now know the AC compressor is low on 134a and doesn't work anyway, it could very well be a blend door problem, and it's broken in the cold position.

https://dodgeforum.com/forum/2nd-gen...-door-fix.html

http://www.heatertreater.net/index.html

 

And if it's low on R134 he should have it checked for leaks.

 

Yup, more than one problem for sure.

 

****. Is all I have to say.
Thanks guys