Got funds together and purchased new duovalve which was indicated by using diagnostics. Had tried "unsticking" and lubing valves on ole unit -- indie says mostly electrical problems with duovalve. A couple of months ago, not only was passenger vent blowing hot air (center was cold) but then drivers' side started with same hot air. So, replaced with new duo. Same problem. Diagnostic #'s 3 and 4 give me elevated readings in upper 150's after replacement. No leaks and job went smoothly. What am I missing?

Does something have to be reset? Please, anyone, advice! Thanks, Rick

Have you had the a/c system checked for leaks? I went through a duovalve replacement on my '98 and when the problem came back, I had a die test done to see if the system leaked. It leaked at the compressor and evaporator. I hope that's not your problem as I just finished paying for mine. OUCH!

No leaks -- foolish me I let out refrigerant and now have to add more as should read in low 20's on diagnostics on a/c panel -- only reading 7 now. But, as it appeared full, initially, and I have no leaks, it still blew hot from both drivers' and passengers' vents. No fuses -- and I checked all three spots containing fuses. Not even sure if it is possible but could I have reversed the three hole connector to duovalve. Thanks for your response and please, anyone, any other comments/suggestions?

Going to shop to buy another can of refrigerant. Maybe......? Will let you all know but, again, any further advices greatly appreciated. Back later today. Thanks, all, Rick

You can't reverse the connector, its one-way only.

Spoke with Ron (Phil's buddy the cert. MB mechanic) says it is probably the control panel module (egads, it's bucks) but that mebbe I should have an indie look at it. I know the system is sensitive to the amount of refrigerant -- am having hard time getting diagnostics to read above 19 on #7 -- should be low twenties -- I should never have let the gas out to begin with -- I know it was fine. Tricky freakin' a/c system and, from what I hear is modeled after the one on Rolls Royce. Further advices always welcome. Will now look for the MB service guys on this site as advised by Ron. --Rick

After speaking with Ron, Phil's MB mechanic buddy who was responsive in calling me back, I was given the the number of a Tennessee salvage yard where I obtained an a/c control panel for 250 bucks! Retail at MB is $873. Plugged it in today and cold air from all nozzles!!!!!!!!

Wasn't easy getting it out. The keys were available at the local MB dealer, the second one for eight bucks while the first had to order 'em for $12.81. It's a little tricky on removal (gotta wiggle the unit downward). Remove wire harnesses (right and a left one) and slide it back it. Now my new duovalves work as does the a/c. Rick