'99 e300d - air conditioning not working
 

I haven't been able to get the air working on my car. It's "new to me", juts bought in January. Yesterday was the first time I tried using the air, no-go.

I should note, I don't have the owner's manual so maybe I'm missing something. I set the temp to "low", turned the fan up and put it on recirculate. Am I missing something simple?

Is the "EC" lamp illuminated on the pushbutton module, and does it fail to extinguish when you press the button?

With a car this complicated, you would be well advised to obtain a copy of the owners manual. If EC is on, no cooling will happen. Steve

For AC mode, you want to red light on the EC button to be off. Usually, the fan would be in the Auto setting and temp ~72. Compressor would then cycle on and off as needed to maintain temp setting.

Answer MattL's questions if that doesnt help.

I accidently left the manual in Montreal at my dad's place. I vaguely remember the PO mentioning EC... is that economy? I can't say I really noticed the light so I'll check that after work.

So, if I turn that OFF, and with the temp on LOW, it should be pumping cold air, right?

That's correct.

It may also be low on freon. Mine has a very slow leak and after a while, it won't put out any cold air. If the compressor is cycling, you will notice a "click" and see the engine load up a little while idling.

No dice. Nada.

I noticed that the compressor doesn't seem to be kicking in. No "click", no drop in idle. If there was a leak, wouldn't it be cycling?

I checked fuses 4 & 7, both are fine. What's the next logical step? Is there a relay I should test?

I have the little sister to your car, its E320, the most expensive surprise with 210 cars when it comes to A/C repair is the darn evaporator, it normally costs somewhere close to $3K to replace the darn thing. Anyone with high mileage 210 is going to face the music sooner or later.

Vahe

Does the red light on the EC button go off, or is it always on?

Does the fan speed increase when the "+" button is toggled in EC mode?

If I hit the EC button, the light comes on. If I hit it again, it goes off.

Yep!

Visually determine whether the compressor is turning with the EC lamp off. If so, you could have a heater fault or very low refrigerant (but still enough to start the compressor). If not, and the pushbutton unit doesn't notice, I have no clue what could be wrong. Perhaps it's a bad pushbutton unit.

Note that it is not normal for your compressor to cycle on this model. The only reason that the compressor should ever shut off is the evaporator getting below 37F. The compressor does not cycle off if cooling is not demanded; rather the heater starts up.

OK, by "visually determine whether the compressor is turning" I take it you mean the center of the pulley. No, it's not moving... only the outside "ring" that the belt touches is turning.

Is there another relay, fuse or elctrical connection I should be checking?

Thanks!

Engine off, key on. Put the left side temp of the CCU on HI and the right side on low (or is it the other way around?) then press and hold EC and Rest for 5 secs. You have 20 secs to do the above. If you take too long just turn ign off and back on and go straight to holding the buttons for 5 secs. Now press right AUTO button to view and toggle through error codes then post. FF means no stored codes. eb1 234 is a code.

Second, turn engine on. Set AC to 72f and AUTO and let warm up. Press and hold REST for 5 secs. Post actual values 1 - 8. Toggle using auto button. Press rest to exit.

There is a fuse in the electromagnetic clutch, but the pushbutton unit should notice if it has blown. Perhaps yours does not for some reason.

If you disconnect the clutch connector and check the clutch coil for continuity to ground, you can determine if this fuse is blown.

Also perform the procedure above to extract the codes and sensor values.

eb1 231
eb1 234
E ff

OK. My display reads in *C, not sure how to change that to F. I set the climate control to 22*C.

1 - 23
2 - 14
3 - 41
4 - 42
5 - 14
6 - 74
7 - 01
8 - 22

B1231 is engine coolant sensor (delays fan speed when cold outside until engine is warmed up and warm air is available)

B1234 is the sun sensor (raises fan speed when in full sun)

#7 is your refrig pressure. Is very low. May have a leak. Pressure is low enough compressor may not be engaging to protect itself. Side issue is why EC light is not permanantly on?

Do you hear any hissing or zing type sounds from the center vents?

Wait for MattL for more, he's much better at this.

So does that just mean those systems were in operation at the time, or are they error codes noting a problem with those systems?

What is the normal pressure? Would my next step be to bring the car in to an AC shop to have its refrigerant recharged?

I'm not sure I understand this part. Why would the light stay on? Or is it only supposed to go out if the AC is engaged... ie compressor turning?

Nothing that I noticed

Thanks again! I am trying to find threads with this kind of info but coming up short... I appreciate your help

If the climate control unit shuts down the compressor due to low pressure, the EC lamp should be illuminated.

There's a version code to ignore low refrigerant level, which doesn't seem to do anything for my pushbutton unit. Perhaps yours is so coded and it works.

The first thing that I would do is check the static pressure on the system. If it really is <2bar, you are almost certainly low on refrigerant (especially at 23C ambient temperature).

This has not been my experience on my '98. When the refrig. level leaked down sufficiently, the AC comp quit running, simple as that. The EC indicator did not come on and the button continued to work "normally" with the indicator turning off and on.

The only thing that told me the AC wasn't working was that fact that there was no cold air coming out of the vents. A look under the hood confirmed that the comp. wasn't working. I have an air gauge type r134 checker and it read nothing so I added some refridg. and it's good to go now.

Ok, so if I understand correctly, if my compressor isn't engaging because of low pressure, the EC light should be on?

How do I check the static pressure?

Before I bring this car to a shop, are their any other issues that can prevent the compressor from engaging... relays, overrides, etc?

I want to do as much troubleshooting as possible before I start paying someone who will likely just start swapping parts in it.

FWIW, the AC hasn't been used since september (by the PO). Don't know if that's a consideration.

Ok that's good to know, sounds similar to what I'm dealing with.

How did you add your own refigerant? I thought only shops could do that, or do you have a shop?

You don't need anything special to work with r134. What I did was this:

Went to Advance Auto and bought the following:

http://www.partsamerica.com/ProductDetail.aspx?MfrCode=IDN&MfrPartNumber=MB134A&CategoryCode=3569

And a couple of these:

http://www.partsamerica.com/ProductDetail.aspx?MfrCode=ADV&MfrPartNumber=A1300&CategoryCode=3571B

And a couple tools:

http://www.partsamerica.com/ProductDetail.aspx?MfrCode=RBA&MfrPartNumber=10945&CategoryCode=3569

http://www.partsamerica.com/ProductDetail.aspx?MfrCode=IDN&MfrPartNumber=GEZ1&CategoryCode=3569

Locate the low side AC fitting on the left inside fender wall near the intake manifold. It has a fluted pastic cap on it. Mine was nearly impossible to get off and I had to take pliers to it. When I put it back on, I just seated it gently rather than horsing it down.

Once the cap is off, start the car, turn on the AC (EC button off) and press that gauge into it to get a reading. If it's low, attach the hose to the can of r134 and to the connector on the car. Turn the valve all the way IN to pierce the seal on the can then back out to let the r134 flow into the system. Leave the car running at this time.

If it does the same as mine, you'll hear the compressor start clicking on for a second or two then shut off. It'll do this repetedly at longer intervals until it stays on constantly. You'll also want to get a bowl of hot water and dunk the r134 can into it in order to get the last bit out as the can will go cold when charging the system and lose pressure.

If you use all of the first can and the comp. is still not running constantly, hook up another and keep filling. Once it does quit cycling, close the valve, remove the connector from the car and take another pressure reading. If it's within spec, take the thermometer and stick it into the center vent with the AC temp set on LO and the fan set in the middle - like 4 bars. You should be able to get the temp to read down to about 45 deg or so, maybe less. If it's not as cold as you like, re-connect the hose and add some more, in small amounts but don't over charge it. Keep checking with the gauge.

That's about it in a nutshell...

great stuff, thanks!

I'll have to check on those r134 cans... I'm not sure if we can get those in canuckistan.

Oh, didn't realize you were in the GWN...

Yes I should update my profile.

I am getting conflicting info on the recharge kits. The FLAPS says they are illegal, need a license to recharge systems here. But my Friendly Local European Auto Money Syphoning Shop says they have seen them at walmart here, but for ~$100

I don't know the status in CA for HFC refrigerants, but I can tell you to avoid using a recharging system which only monitors the low side.

Be sure to measure the high side WITH A GAUGE while filling. DO NOT rely on the reading at #7 to tell you if your high side is too high. There are a few things that can cause the head pressure at the compressor to greatly exceed what you see at reading #7. The fact that this reading exists makes people want to cut out this very essential corner.

B1231 & B1234 are error codes.

The first is providing implausible data. The second is a very common failure that most of us ignore.

That's good to know. I'm typically VERY conservative when adding refrig. - only putting in as much as needed but you're right, no substitute for using the right equipment.

I needed a set of r134 gauges any way unless I can just convert my existing set of R-12/22 gauges! :)

The engine coolant sensor could have been getting some odd reading when I first Tee'd into my coolant lines for my WVO system. I had some air bubbles for the first week or so, and poor flow through the heater. Working fine now, I wonder if that's what triggered the code.

not much luck finding those AC recharge kits up here.

The fittings are different for R12 (1/4 SAE) than for R134a (1/2 ACME), but there are adapters available.

Quick question... Are these the guages I need to do what Matt describes?

http://cgi.ebay.com/ebaymotors/a-c-ac-Manifold-Gauge-and-Hose-Set-r134-r-134_W0QQcmdZViewItemQQcategoryZ43989QQihZ017QQitemZ270231185451QQrdZ1QQsspagenameZWDVW

http://cgi.ebay.com/ebaymotors/MAC-134-AC-guage-set_W0QQcmdZViewItemQQcategoryZ43989QQihZ012QQitemZ220224932464QQrdZ1QQsspagenameZWDVW

http://i23.ebayimg.com/06/i/000/eb/c6/7287_1.JPG

How do the lines hook up? Looks like 5 lines... one to the 134 can, one to the "high" side, one to the "low" side... where do the other two hook up?

It's been 4 years since I worked for Benz, but I recall leaks at the line (low side ?) to the dryer to be common on 210's.

Notfarnow, that set looks to be what you need. There are lots of brands and models, but they all share the same stuff. Skip Ebay and go with a reputable seller, such as a brick and mortar store or a place like ackits.com.

You need to ensure that you get R134a fittings (which it looks to have) and 1/2 ACME fittings for the refrigerant hose (yellow). I can't tell the fitting size from the image. 1/4 SAE is standard for R12 and R22, so these are sold too. Of course they are not interchangeable, but adapters are available.

There are three lines there. There is one red and one blue hose. There are "blank" connectors on the sides of that unit to clip unused hoses, and that's where they are clipped.

Thanks a ton, matt

So when I get the guages (I am having a hard time finding them locally), what pressures am I looking for as I charge the system?

I maybe could've perhaps not-quite-sure have/will have/could have some r134 that mighta(maybe) fell off a truck

There isn't one correct pressure. It's a set of charts. When you get the equipment, I'll track down the charts (if someone else doesn't beat me to it).

right on, thanks

Be sure to thoroughly understand the operating instructions on the gauges. Unless they're different than mine, it's possible to open the valve on the high side and allow high pressure gas into the r134 supply can and blow it up in your face.

I have never seen a manifold set where this was not the case.

So the "blow up in your face" feature is non-optional? Not ideal

Less than ideal, that is true. But it is the industry standard tool.

OK, I expect to have the gauges tonight, and I have some r134.

My understanding is that I feed to the low side, and periodically close the valve before checking the pressure on the HIGH side.

Also, where is the fitting for the "high" side? I haven't been able to find it

I occasionally top off my AC via the low pressure side feed with a simple guage from Walmart - don't really need anything else if you're looking to add freonto the system - on the ACC panel, if the #7 (I believe) reading goes to 30 then it kicks off the compressor. Usually in the high teens or low 20's is where I've found my AC to run nicely. If it's lower than that I will add a small can of r134 freon to the system to "top it off" ....

The high-side fitting is located at the left (US driver's) top corner of the condenser, in the front. There is a small plastic cover on mine which clips to the auxiliary fan shroud.

At some point, it is a good idea to check the reading at #7 against what you read at the high-side port. The pressure and temperature transducers are located on the outlet of the receiver/dryer.

A restriction in the condenser or dryer will cause the high-side to exceed what you see at the transducer (and thus at the #7 reading, if everything is working correctly). Sometimes it will exceed the value significantly. If so, the compressor will see dangerously high pressures but the climate-control system will not shut it down.

The compressor will kick off if the pressure is too high on #7.

If the pressure reading at #7 is incorrect, what shuts it off?

As I said, a restriction in the condenser or the dryer will cause the reading at #7 to read artificially low.

Mine reads 4 with 350psi at the high side.

As for specifics, I can't tell you. But, if the value for #7 hits 30, the compressor kicks off and it will go back on when it lowers. As soon as it hits 30, it'll kick off.

Been there, done that. I topped of my system a few years ago and this occurred. Nothing like a ballpoint pen to relieve some pressure on the low side when in a pinch...

I believe that I went into the specifics. Specifically, the value read at #7 can be dangerously wrong if there is a restriction prior to the sensor. In fact, there is a DTB for my car for this very issue. See the attachment.

While this does not apply to your later car, it is possible to plug the drier even if it contains no fault. Too much water in the system can do this, as can using sealers.

I infer that my drier is plugged from several pieces of information. First, the value at #7 is very, very wrong. Second, both values at #7 and #8 go DOWN upon compressor engagement. Third, the line coming from the dryer is cold to the touch. It should be hot.

Don't worry, I'm getting it fixed. But note that with the fault that I have now, there is absolutely no cutout for high head pressure. I believe that I have been venting refrigerant because of this, since no leaks in the system are apparent. I haven't checked the evaporator except by sniffing the vents, but tomorrow it is going on a lift to sniff the drain tubes.

I got my AC gauges.

Two questions:
-what pressures should I be watching for?
-I still can't find the "high side" port. Where is it exactly?

It's at the upper left corner of the condenser. Remove the cover over the auxiliary fan, then remove the small plastic door at the top left of the fan shroud.

As for the pressures, the chart is in the FSM and I don't have that with me just now.

anyone have a set of charts handy for the high & low side pressure I should be watching for?