RE: Heat problem with Plymouth Voyager

I have a 1996 Plymouth Voyager (3.0l) with about 185,000. Recently the heat has not been working. The air blows but it is lukewarm at best. My usual mechanic looked at it and orginally thought it needed a new heater control module. After being scared away by the price of a new one, I looked online for a used one and was about to order it when when one of the sales guys happened to mention that it needed to be brought to the dealer to be programmed. I mentioned this to my mechanic, who then checked with his "computer guy" who told him, based on the mechanic's summary of the problem, that replacing the heater control module with a used OR new one would not necessarily solve the problem because (and I don't really follow all of this) Chrysler is not like GM and doesn't readily share the codes (?) Or something like that. So, they both advised that I simply take it to a Chrsyler dealer. No offense to dealers, but I loathe to do that because I think they often overcharge. So, I had another mechanic friend (who works for GM) look at it and he thought the heater core needed to be flushed since one hose was hot and the other was not. But he could not do it since he was on his lunch hour and was doing me a favor. So, I brought it to another mechanic around the corner from me (mechanic #3) and asked what he thouhgt the problem was. He flushed the heater core, disconnected the a/c compressor, and said it was fixed. The only problem--it is still the same lukewarm air and is defintely NOT fixed. For the record, mechanic #1 (my usual mechanic) said it is definitely NOT the heater core. I still have to talk with him to see why he thinks this. Although he appears to be right (contrary to mechanics #2 & #3), how does he explain the one hose being hot and the other not? At any rate, I have three guys with conflicting diagnoses and a van with very poor heat and a wife who wants to give me her van and take my car. HELP!