How difficult is it to rebuild a A C servo
 

The a c servo is not working on my 1980 300d. The lines to the servo are hot but the lines leaving to the heater are all cold. A new on is far to much for me. I've checked the yards and couldn't find one. Is there a kit out there to rebuild one. Is it very complicated once you've opened one up. Perhaps someone knows of a DIYS tutorial i can link to. Is there a part of it that fails more often than the rest. Are there any places they sell them cheap. My car is a keeper, I would just like HEAT. Thanks RAY M

Does anyone think it could be my heater valve. I've never seen one of these but along with my servo i have a heater valve. see pic.

Where did you find that picture? I own a 79 and haven't seen that part. I think that the rebuild would be easier than finding the parts for it. There are several places that run auctions on E-Bay that rebuild them for aprox 350 exchanged. This is the way I would go.

I found it on ebay for $17.00 Item number: 300079746973
I don't understand why I have both. or are they both suppose to be there. RAY m

Perhaps someone has bypassed the servo in the past. There shouldn't be a heater valve and a servo. The servo serves the function of a heater valve.
I don't recall anyone successfully rebuilding a servo on this board. A used, rebuilt, and the new solid state ones are your best choices I think. Or, bypass the hoses (which may already have been done).

ray, kerry
i have the servo and the valve. well at least i have a valve that looks a heck of a lot like that, just next to the firewall on the passenger side.

when you suck on the line does the part move? if it does then the part is good.
Your A/C servo is like a giant watch. my 1980 300TD and I went around this issue for a year before she would work properly- and that was because I had acces to a/c servos in the yards here of south florida. Lithium grease, digital pics and a steady hand are your friends if you intend to repair your current unit. I could find several unit in the yard her that may or may not work- but my cost is $40-$60$- no testing at all- and I have a 30 day return. Finding, pulling, packing, shipping and taking the risk of returning and non payers makes the do it/dont do it value to me in dollars about twice my cost. So take yours apart, slowly, carefully, with pics, and see if you cant fix it- if you are mechanically inclined and have tools. If not, buy a $15 12 volt space heater.

Thats exactly where mine is. The vac line that goes to it comes from the servo. it is a white vac line. Do you think this was an unsuccessful attempt to by pass the servo. RAY M

thats where mine is, but mine is a white/black line i believe. its too dark to go see right now. i dont think its a aftermarket bypass. on mine it looks very very factory/stock. also, i HAD to completely bypass the servo by completely removing it before i had heat inside. so i doubt very seriously that this is a bypass. why would mine have the servo still connected as well as the valve?

If i remove the servo or just reroute it by running another hose from a Y split around it will that bring heat. Will that affect the a/c later in the summer. Maybe fitting an open shut valve to shut it off in the summer. Is this sounding easy or am i missing something big. Please advise. I don't want to mess up anything. RAY M

i cant speak of the ac issue, since i have not had mine working. was broken when i bought the car. if it makes sense, this is what i did. i removed the all four hoses from the bottom of the servo. pulled the electrical and vacuum lines, there are also two on the very bottom of the servo as well. and pulled the servo out of the car. my aux pump is attached to the same bracket as the servo, so it came out as well. i then just put plastic hose connectors/pipe between the hoses and i have full heat in the car now. so hot that i have to turn it off and on, and then eventually roll down the back two windows to even it out. i know, i know....but i just havent had the time to go to part yards to pick another servo up. and i REALLY dont have the money at this time for a new or rebuilt servo.
here is a pic of your system, i think, and you can see how the water runs through the servo (regulating valve).
http://www.peachparts.com/shopforum/attachments/diesel-discussion/40174d1168228570-hose-locations-heater-servo-79-300d-123_heating_water_circuit.jpg

I have a Good servo, and a bad servo, and one that works for a little while, then you have to turn it off, wait a sec and then turn it on... I plan to swap in the good one, and take apart the bad one, then figure out what could be wrong, then fix the sorta working one. I also have two unknown ones... if anybody wants pics, I could post them.
John

Show any pics you have and let us know of your disassembleage luck. RAY M

how about this do o you think this would work. see picture. red is the bypass blur a shut off valve

i had to take my aux water pump out as well, since it was shot. when i took it apart, it had more than a few burned windings. so im gonna have to pick up another one as well. even without the aux pump, i still get blistering heat inside. the reason i say this, is because you have a valve after the aux pump in your drawing. with the valve off directly after the aux pump. if the pump isnt being shut off when the valve is switched, then you could have some pressure building up and a leak develop. you might want to set it up where some flow recirculates back around to your other bypass hose when the valve is closed.