The evil servo is not so evil, but Norm is still AC less!
 

Hey guys,

As you may remember, Tyler posted that Norm had a bad climate control servo and thus ordered a new one to be replaced and installed.

Well I had that done over the last few days, but to no avail. I took Norm in last Thursday, and just got him back today. My mechanic told me that the aux. water pump was ceased, so he replaced it. He installed the new rebuilt servo, and nothing happened.

Now here is where it gets fishy... My mechanic said that the next thing to replace is the "de-ice switch" which would cost about $620. Obviously I told him to hold off on that. But what exactly is a "de-ice" switch? I hope it's not just the defrost switch on my AC cluster, but no way should that be so expensive!

Anyone know what this thing is? And if this is not the problem, anyone know what else might need to be replaced to get the ACCII working? It's a little baffling really!

Thanks for the help guys!

I have no idea what a de-ice switch is. What was the original problem?

^Same here, that's why I'm a bit baffled...

The original problem was thought to be the climate control servo, that it was dead, so Tyler sent me one with Norm when I bought him. While that was being installed, it was found that the auxiliary water pump had ceased, so that was also replaced, but the system still does not work. My mechanic then told me that the de-ice switch was bad, so I'll have to have that replaced.

I'm just a little confused, thats all...

I've never heard of a de-ice switch...
Is the mechanic German?
Maybe he means the monovalve? That can be repaired easily. Does it blow at all, or does it just not blow cold? Do you have heat in high and low settings as well as defrost?

I know you thought the servo was bad. What was it doing to make you think it was bad?

He's probably talking about the ACC amplifier. When the AUX water pump fries, it takes out the amp with it, or vise-versa. You can take off the glove box inside by taking off the small clips inside the glove box. It's a small circuit board in a black plastic housing. If it's fried, the ACC won't work. You can check if it's toast by looking for burned contacts on it, IIRC rebuilt ones are about $100, you can try to fix it by re-soldering all the joints.

To remove the ACC amp, remove the glove box inside by prying the clips off, take off the amp by loosening 2 screws and unplugging a harness. Also you can test the amp with a multimeter, seach for the exact procedure. New from MB the board probably cost $500 or something rediculous, but rebuilts are good.

I have nothing, it pretty much just blows air and thats it. No cold air, no heat, just air.

That might be what he is referring to, that piece I have heard of. Neither one of them are German, but I could see him calling it that.

Tyler's thread was deleted, but I remember him telling me that heat and cool air worked sporadically, and mostly not at all. Finally it just stopped working all together. If he sees this I'm sure he'll explain, I read the thread but don't remember a ton about it.

This actually sounds familiar, because he told me he would have to get behind the glovebox to fix it. I'll have to open up the glovebox when I get a chance and check it out. This might be exactly what he is talking about. From fastlane, $230, not too bad considering what I could pay...

Colin doesn't have a mono-valve.

Check you local junkyards for a climate control amp. That sounds like your problem.

Yup, my thread was deleted because I was posting competitors to fastlane for a servo rebuild.:(

From what Colin told me over the phone, I interpreted it as the guy doing electrical tests of the CCU itself, and the de-ice or perhaps defrost was causing the system to go nuts.

Perhaps he thinks the climate control is fried, and $600.00 retail for a rebuild sounds about right. Of course, you can find good ones for less than half that price.

I was hoping to get the part number so we know exactly what they're talking about.

Soon to be good used Servo for sale in the parts section...:o Oh well, it was a good thing to replace anyway.

^^Oops, forgot to mention that Norm is a 1980 300TD, so there is no confusion again :D

Will do, but sadly there are no really "good" junkyards around here with any 123's sitting in them. I will take a look though!

Thanks for the help guys!

^Yeah I asked about a part number and he said he was going to email it to me tomorrow morning. I picked Norm up on his way out of the shop, so I wasn't going to make him unlock it for me again. I'll post it when I get it in the morning...

Sorry about that!

I have a line of text listing my cars so the dial up folks don't get cranky. Someday they'll enter the 21st century.

George Murphy sells rebuilt servos and amplifiers, and vacuum diaphragms. IIRC, a rebuilt amp from him is around $100.

Used working ones are $30 shipped on ebay. Search "Mercedes climate amplifier" to find them.

http://img329.imageshack.us/img329/7...6123107he7.jpg

They look like this.

I had to deal with fixing the servo climate control system, and it completely works (it's nice!) so if you need help feel free to ask me. There is a learning curve on ACC work, particularly the older version.

That servo amp is very likely your problem. I've never pulled one out of a car at the yards that wasn't fried. Most of them you can see the burned area!! :eek:
I hope your mechanic fused your aux water pump. If not you need to do that or have it done.

Hmm, I'll have to check that out. If I can get one for $30 shipped, that's awesome! I need to save any penny that I can with Norm! I'll look in to that, thanks!

Yeah he fused it. This is one of the many things he told me about what he did over the phone. See, I can't retain everything that he says, because if I could I could probably rebuild Norm from the ground up! That's why some times I sort of sound "fishy" when talking about what he has done.

He's really thorough and really a great mechanic, but he really likes to replace EVERYTHING possible. I guess if your pocket is deep enough, that's great, but mine isn't really. He really knows what he is doing, I just have a hard time keeping track of all of it! He also uses terms and part names (like the deice switch) that I have never ever heard of, so that throws me for a loop as well.

Oh well, crisis averted I suppose. Thanks for the help!

For the money spent on the servo and other installation and diag, you could have bought the digital servo and been done with it and have a working system.

You just had to rub it in, didn't you.:D

I need to start pulling these things......*daw makes notes*

... I have a 78 D and an 80 TD... parts cars if you're needing something...

Okay, so I got the part number, and it turns out it's the evaporator temp switch, also known as the "de-ice switch" because it kicks the compressor off if the evaporator is froze/too cold to prevent the compressor from killing itself.

I'm actually leaving for Indy in a little bit, but once I get back I'm going to pull the amplifier and see if that also might need replacing, otherwise it's the evap. temp switch that I'm looking for. Fastlane has it, but here is the part number anyways: 003-820-24-10.

Thanks guys!

Do you know if a failed amplifier will cause the blower to stop blowing? The blower is not blowing on my 116 right now and I'm trying to diagnose it. I haven't been able to get good enough access to check the voltage at the blower motor yet, and the amplifier is far more accessible. Do you know if I can check at the amplifier for voltage to the blower?

Okay, sorry to bring up a dead thread but I am bored and want to try something. How do I "jump" the compressor to see if I can get it to come on? I just want to try it to see if it works, I have a CCU on the way but if it's not too invasive of a process I'd like to give it a try.

Any tips/how-to's on what to do? It's getting hot here!

Applying 12 volts to the compressor clutch will make it come on :) But, without having a temp switch on the evaporator to shut it off at 32* it will turn into a block of ice.

-Jason

^I'm trying a new CCU, then the temp switch. I tried to jump the low pressure switch on the evaporator today to no avail, so I just wanted to make sure my compressor came on at all. I guess I will just wait so I don't have a ton of extra wires everywhere from the jump to the compressor. I was going to do it more as a test anyway.

One place I took it to seems to think it's the CCU, the other the temp switch. If neither of those work then I'll try relays. If that fails, then poop.

Okay, I got the compressor to come on today. I jumped the evap temp switch, and sure enough it switched on. I still think the CCU is bad though, because it will still only blow out warmish air, which is what an indy here told me might be the problem. However, I will also need to recharge the system as well so that might do some good in terms of cooling things down!

Hopefully that'll do it! I'm pretty happy I got it working today!

You sure what you jumpered was a temp switch? If the charge level is too low there's a pressure switch that will keep the AC from coming on.

-Jason

Unless something happened over the past few months , the ac Should have a charge. My guess is it's trying to cool hot air.

That's what my AC does.:P

but anyways I dont have any experience with these servo thingys, so good luck..........



( maybe a heater valve out of an older vehicle and a choke cable mod to control coolant flow- that would be my fix if I was faced with a $1K plus repair bill on one of those units. )

^Well the servo is brand new (well, rebuilt) so right now I'm going to rule that out as a problem. I've replaced the amplifier,and I have a CCU and a new evap. temp. switch on the way.

I have noticed that my center vents don't work but are hooked up to the vacuum pod, and the vacuum pod that closes the blower "door" doesn't close it (it tries though) and the passenger vent is less powerful then the driver vent. Could there be a vacuum leak somewhere causing all of this?? Does ANY of this sound familiar?

I'm just happy I got my compressor kicked on!

Okay, today I went out and bought a recharge kit from Wal-Mart which included three cans of 134, a little trigger dispenser hose thingy with a gauge, and some 134 conversion stuff (but I didn't need that).

Anyway, I hook it up to take a pressure measurement like it says to do, and it shows a whopping zero. So okay, I plug in a can and empty it in to the system. Once again, nothing. I gave trusty Tyler a call, and then dumped in one more can. The gauge would jump a little, then go back to zero.

This is with the compressor on and the dial all the way in the coldest setting. Very interesting, I'm guessing I have a leak somewhere but I couldn't see anything coming out anywhere.

And to add insult to injury, I crushed my phone in the hood today. Killed it instantly. Arghhhh.

Does it not have the dye? I'm kind of worried that you were not able to find where 2 cans leaked out. Hopefully not the evaporator.

It doesn't say anywhere that the cans I bought have dye in them, so I think I will go get some tomorrow that has it in it. I have a couple things to get at the autoparts store as well.

Should I try stopleak just to try?

I pray it isn't the evaporator. That's going to be a hell of a repair for me to do.

My two experiences with AC have been very fortunate, just charge and go, so I don't know what to look for. Hopefully someone will chime it.

Yeah, I was hoping that this would be the case but alas. Oh well, I'll have it looked at again but man the labor would kill me. I would totally do it myself if I had a garage.

First off, as I have also learned, do NOT set your phone down under the hood. My son slammed his Iphone in his hood {Mazda 3} and even sticking halfway in/out it was undamaged. My Samsung Eternity didn't fair quite as well when I slammed it in the hood of the white wagon. Bottom buttons are cracked but believe it or not the display was OK. Whew......
On your AC, I really wish there was a forum member close that could help you with this. Don't just keep throwing cans of freon in there. Go to Autozone and use the tool loner program and get some of their gauges. We need to see pressures.
Then consult the forum on proper hook up of them and go from there. Don't trust the little gauge you got with the kit.

^Okay, I'll go out and get some tomorrow. Might be worth it to me just to buy. Harbor Freight has some for like $40. Not too bad.

And my phone is just completely smashed. Nice penetration right in the middle (that's what she said) that cracked the board. Won't even light up a little.

A can of green dye is cheap, you can put that in and see where the leak is. It lights up bright under a UV light.

-Jason

My only question with the dye is how would I be able to see it at the evaporator?

Process of elimination :(

Also, keep in mind that the leak may have leaked all the oil out of the compressor too. If it were my car, once I found where the leak was I would remove the compressor, dump the remaining oil out, and add the correct amount of new oil, then fix the leak and vacuum the system down.

-J

I give up, Norm is going to the mechanic. I replaced the evap temp switch today which worked, the compressor comes on, but the CCU replacement is way too involved for me.

It's all confusing, the receiver gets cold and frosty, but yet all my vents are warm. Ugh, I quit. I just want to be cold again.

So, the condensor gets warm/hot like it should, and the return line (big one that goes to the compressor) gets cold?

If so, your heater core may be staying filled with hot coolant, like in winter time. Does the Servo systems also sport the monovalve?

Sorry, I meant condenser. But yes it gets cold, didn't check for hot but I can do that easily (I'm assuming it does as the frost goes away rather quickly). Where is the heater core? I haven't checked the engine line either, but I will do that now. I am under the impression that the servo does not have a monovalve, but hey what do I know, it might!

The servo is a rebuilt one freshly installed in January.

Let me go check those things out.

Colin,

The condensor should not get cold. That is the part in front of the radiator. The evaporator gets cold (inside the dash). The heater core is also in the dash.

The heater core is the last thing the air goes through before exiting the vents. That is why you can run the compressor, but still get warm/hot air through the vents on cool, humid days, to keep the windows from fogging up.

On cars without the servo, like mine, an open monovalve lets water into the heatercore, resulting in hot air, even though everything is set for cold air.

Okay its the thing that's behind the glovebox, with the four tubes going in to it. Looks like a little aluminium box. I know it's one of the things you replace along with your dryer when you replace the compressor, the name just escapes me right now.

What would cause the heater core to stay on or keep hot, or whatever?

There is a monovalve repair kit under the 1980 300TD category on fastlane, so I'm assuming that there is indeed a monovalve. Where is this normally located?

The little silver thing is the expansion valve. The monovalve is usually on the fire wall near the battery. I do not know for sure, as my car does not have the servo.

http://i435.photobucket.com/albums/q...n/IMG00008.jpg Is it this thing?

There is a little lever on the back that does NOT change position at all, even though it looks to be vacuum operated.

Also I would not say my return side line was freezing cold, but it was cool to the touch.

The non servo type monovalve is electrically controlled. It is possible that the servo type is vacuum controlled. It is hooked up to a heater hose, so that may be it. When the engine is a normal operating temp, one side should be cooler than the other. Both sides having the same temp means either the heater is on, or the valve may be defective.

Yeah, the black hose coming out of it goes straight to the servo. I traced it there. I also tried manually closing the valve by pushing it forward, but didn't feel a difference in vent temps. Maybe I should try and hold it down longer, I don't know.

I will still take it in on Monday to see what they can tell me is wrong. I might just do the work myself, I know I'm capable of it, I'm just not capable of diagnosing!

Man I wish there were more people around me to help out!

I understand that one! Lucky for JimmyL is close by.

Good luck!