Mercedes: no heat, cummings diesel, dsl faq

Question
My friend has a cummings diesel in his truck i think it's a 5.7. 2003 dodge his heat is not there after half an hour or more and never enough to melt the snow on his widow.Been at the dealer's 8 times and still nothing.Thay changed hoses and the stat and still nothing. Can you help as to why there is no heat. thanks Richard.

Answer
Please read the document at this address:

http://dodgeram.org/tech/dsl/FAQ/cold_wx.htm

Long idle will never warm up the engine, only clog the catalytic converter and coke up the injectors.

Have a great day.
P.S.
Here are some other links you may like:
http://www.dodgetalk.com/
http://dodgeram.org/support_pgs/diesel_ix.htm
http://dodgeram.org/