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#1
08-23-2008, 12:24 AM
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Replaced Servo - Now I have no heat
I have had a leaking Servo unit for several months and just got around to replacing it today with an aluminum one (used) - went well, easy install. But, now I have no heat in any settings, including Defrost - A/C works fine. It was 90 degrees here today, but I couldn't get any heat.
Any suggestions - or troubleshooting tips? Never had a problem with heat before this... ryan
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RG Newell 1984 300D 1972 250 1986 560SL 1991 300CE 
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#2
08-23-2008, 12:31 AM
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did you completely bleed out ALL air from the cooling system? they are VERY hard to get all the air out. you need to park the car with it's nose up as high as possible, and open the upper radiator hose, and pour all the coolant in through the hose, until coolant exits the upper radiator fitting. then attach the hose and finish the fill.
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread "as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do! My drivers: 1987 190D 2.5Turbo 1987 190D 2.5Turbo 1987 190D 2.5-5SPEED!!!  1987 300TD 1987 300TD 1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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#3
08-23-2008, 02:03 AM
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if i remember correctly the vacuum lines on the bottom of the unit go on one way only, if they are reverese you will not get heat. this is a cold lockout feature that will not allow to operate until the car is up to temp
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1967 250 S 1967 280SE 1968 250S 1971 280 SE 1973 220 1974 280 S 1975 450 SEL 1976 220 D 1979 300SD 1983 300 SD 1985 230 TE euro 1986 280SL 1986 500 SEL euro 1986 190E 2.3 1990 300 SE 2003 C230 K 2004 C230 K 1987 560SEL 1987 300SDL now in canada 2005 C230 1998 C43 AMG Sold to DON 1993 190E 2.6 300TD Former daily driver Totaled current: R320 CDI Ram 2500 Cummins
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#4
08-23-2008, 08:51 PM
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I just tried to add coolant and the upper hose is full - I don't think I have air pockets as car seems to be warming up as it should...
The hoses on bottom are hooked up just as they were before... Any other ideas? ryan
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RG Newell 1984 300D 1972 250 1986 560SL 1991 300CE
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#5
08-23-2008, 09:36 PM
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possibly a bad amp? or the servo you bought may have failed, the aluminum ones also can have issues. after cycling the heat on and then turning the car off, do you hear the servo return to the park position?
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1967 250 S 1967 280SE 1968 250S 1971 280 SE 1973 220 1974 280 S 1975 450 SEL 1976 220 D 1979 300SD 1983 300 SD 1985 230 TE euro 1986 280SL 1986 500 SEL euro 1986 190E 2.3 1990 300 SE 2003 C230 K 2004 C230 K 1987 560SEL 1987 300SDL now in canada 2005 C230 1998 C43 AMG Sold to DON 1993 190E 2.6 300TD Former daily driver Totaled current: R320 CDI Ram 2500 Cummins
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#7
08-24-2008, 03:17 PM
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Quote:
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1967 250 S 1967 280SE 1968 250S 1971 280 SE 1973 220 1974 280 S 1975 450 SEL 1976 220 D 1979 300SD 1983 300 SD 1985 230 TE euro 1986 280SL 1986 500 SEL euro 1986 190E 2.3 1990 300 SE 2003 C230 K 2004 C230 K 1987 560SEL 1987 300SDL now in canada 2005 C230 1998 C43 AMG Sold to DON 1993 190E 2.6 300TD Former daily driver Totaled current: R320 CDI Ram 2500 Cummins
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#8
08-24-2008, 03:20 PM
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Everything was working fine before the switch - except, of course, for the leaking! I guess it's possible that I blew a fuse, or the amp, during the installation process. I have checked the fuses at the panel (driver's side), but I don't know where there any other fuses..???
The AC still works fine... Is there a way to just check the servo - to see if it will even run? ryan
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RG Newell 1984 300D 1972 250 1986 560SL 1991 300CE
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#9
08-24-2008, 03:22 PM
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well it is likely the replacement servo is the issue, as i said earlier the aluminum ones also fail.
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1967 250 S 1967 280SE 1968 250S 1971 280 SE 1973 220 1974 280 S 1975 450 SEL 1976 220 D 1979 300SD 1983 300 SD 1985 230 TE euro 1986 280SL 1986 500 SEL euro 1986 190E 2.3 1990 300 SE 2003 C230 K 2004 C230 K 1987 560SEL 1987 300SDL now in canada 2005 C230 1998 C43 AMG Sold to DON 1993 190E 2.6 300TD Former daily driver Totaled current: R320 CDI Ram 2500 Cummins
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#10
08-24-2008, 03:29 PM
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Yea, you're probably right - is there a way to check the thing before I just ditch it? I bought it on ebay a couple of years ago - got a good deal, but I'm stuck with it.
ryan
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RG Newell 1984 300D 1972 250 1986 560SL 1991 300CE
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#11
08-24-2008, 03:37 PM
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i have never opened one before, you could try to open it and see if the jam is obvious, there is a way to test tthe motor but i do not recall what it is
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1967 250 S 1967 280SE 1968 250S 1971 280 SE 1973 220 1974 280 S 1975 450 SEL 1976 220 D 1979 300SD 1983 300 SD 1985 230 TE euro 1986 280SL 1986 500 SEL euro 1986 190E 2.3 1990 300 SE 2003 C230 K 2004 C230 K 1987 560SEL 1987 300SDL now in canada 2005 C230 1998 C43 AMG Sold to DON 1993 190E 2.6 300TD Former daily driver Totaled current: R320 CDI Ram 2500 Cummins
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#12
08-24-2008, 03:50 PM
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I found this post- see reply #15 where a procedure to test the servo motor is explained.
http://www.peachparts.com/shopforum/showthread.php?t=194635&highlight=checking+ACC+servo I tried it and my wires got really hot, really fast! And the motor wouldn't run... Not sure why they got so hot, but it appears that I clearly have issues with the servo... ryan
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RG Newell 1984 300D 1972 250 1986 560SL 1991 300CE
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#13
08-24-2008, 03:52 PM
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Quote:
__________________
1967 250 S 1967 280SE 1968 250S 1971 280 SE 1973 220 1974 280 S 1975 450 SEL 1976 220 D 1979 300SD 1983 300 SD 1985 230 TE euro 1986 280SL 1986 500 SEL euro 1986 190E 2.3 1990 300 SE 2003 C230 K 2004 C230 K 1987 560SEL 1987 300SDL now in canada 2005 C230 1998 C43 AMG Sold to DON 1993 190E 2.6 300TD Former daily driver Totaled current: R320 CDI Ram 2500 Cummins
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#14
08-25-2008, 10:32 AM
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A couple of operational questions - 1) does the servo motor run at all when the system is on A/C? I still have good A/C...
2) Also, if there is an air pocket, would this prevent the servo from operating? 3) Will the heat even operate in this car if ambient temps are in the 90's? 4) Would a bad auxiliary water pump contribute to this problem? I am just not yet convinced that this rebuilt servo is bad - I tested the old one by connecting a 12v source to the leads on the servo (according to the above link), and the old motor didn't run either. Now it's possible that if the servo doesn't operate while the system is cooling, maybe that old servo is/was bad as well - since I haven't operated the heating system since Feb/Mar. ryan
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RG Newell 1984 300D 1972 250 1986 560SL 1991 300CE Last edited by rgnprof; 08-25-2008 at 11:04 AM.
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#15
08-26-2008, 04:24 AM
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Quote:
2. unit should cycle even if there is an air pocket 3. yes 4. no, the aux pump will only run when temp is below specific temp
__________________
1967 250 S 1967 280SE 1968 250S 1971 280 SE 1973 220 1974 280 S 1975 450 SEL 1976 220 D 1979 300SD 1983 300 SD 1985 230 TE euro 1986 280SL 1986 500 SEL euro 1986 190E 2.3 1990 300 SE 2003 C230 K 2004 C230 K 1987 560SEL 1987 300SDL now in canada 2005 C230 1998 C43 AMG Sold to DON 1993 190E 2.6 300TD Former daily driver Totaled current: R320 CDI Ram 2500 Cummins
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