BenzWorld Junior Member
Date registered: Jul 2010
Vehicle: 1998 E300TD - previously owned 190, 82 - 240D 89-E-Wagon & 82 - 300sd &80 - 220 + 69 TR6 & 76-TR6
Location: Greenville, SC
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try this one as you seem to know what you are talking about. On my 1998 E300TD the AC works ok when the car is first started. However is I stop and start after heating up the side vents, both usually, will blow hot, while the center vents blow cool. Sometimes both side vents are hot sometimes only the drivers side. If I wait long enough it "sometimes" slowely corrects itself and starts blowing cold. I can switch to Defrost for a few seconds, allow the vents to shift and then go back to the normal AC postion and this sometime fixes the problem.
I do not think it is the duo valve as both side vents are involved and duo valve would be one side only as I understand it.
Where do I look next. Are the vent damper vacumn controlled. Is there a diagram somewhere. this is a desiel, and on my older diesel vacumn is always the answer to these type problems.
I did open the duo valve and looked clean except that stim seems to be slugish moving inside the solinod. also ran diagnoltics. below.
Here are reading with engine NOT started:Outside Temp 74
1=24, 2=23, 3=30, 4=29 , 5-31, 6 = 32, 7=05, 9=85 Engine at rest
Next: Engine running Outside temp 74 = inside temp set at 72 both sides after 3 min
1=27, 2=26, 3=39, 4=37, 5=39, 6=54, 7=23, 8 = 71 All vent not cold yet.
I then Shifted temp to 68 and noticed system engaged vents moved, center and driver side blowing cold but passengers side blowing hot.
Had 10 minutue commute ( welcome to SC) with everying blowing cool except passenger side vent. Outside temp = 75
1=27, 2=25, 3=23, 4=68, 5=28, 6=80, 7=25, 7=77
got any suggestion. should I go back and lubricate duo valve stem. ??
Still think vent flaps are involved... but will try anything now. have not added r134 as that has not been suggested and center vent blow very cold so do not think freron is problem.