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Help a noob recharge his R134 Pages: 12

curtis73 on Sun March 29, 2009 7:30 PM User is offlineView users profile

Year: 1999
Make: Mercedes
Model: E300
Engine Size: 3.0TD
Refrigerant Type: R134
Ambient Temp: 65
Country of Origin: United States

First of all, a little background. I have done an A/C recharge once with a buddy but that was about 10 years ago. I own a good manifold/gauge set and I need to recharge my wife's car. It leaks evidently because it hissed in the dashboard for about a year, then it started getting warmer, then it quit and the car has disabled the compressor like it should. It was also accompanied by a P0600 code which is a serial communication error which is common on Mercedes with low refrigerant. I know the leak needs to be addressed, but it has taken 10 years and 200k miles to leak out, so I'm just going to recharge for now to get her some cool air.

-I found one AC valve behind the grille near the condenser, but I can't find the other valve. Anyone know where it is?
-How do I tell the car to turn on the compressor so I can charge it? I could run a jumper to the compressor, but its tucked way away and not easy to access. I gotta think that Mercedes has a test lead or a set of buttons I can press to kick it on. Or... do I start charging it and the increased pressure will trip the switch and make it run on its own?
-I won't ask you "how do I charge it," but is there a good link you can recommend where I can read up on it? I'm sure it will all come back to me but I want a DIY rundown of how to do it.
-This is the big question I have: Should I get just plain R134, or should I get some with oil in it? How about leak dye? Both? If I need oil, which kind of oil do I get? It comes in both types. How many cans should I have on hand for a full charge?

-------------------------
1966 Pontiac Bonneville
1973 Impala Wagon
1987 BMW 325 convertible
1996 Impala SS
1997 Toyota Tercel

Matt L on Sun March 29, 2009 9:29 PM User is offline

For general information, there is a lot of information in the "Procedures, Tips and FAQ" forum. That's a good place to start.

No way to jumper the compressor on that car without simply applying 12V to the compressor clutch coil, and I do not recommend that at all. The whole system is computerized. There is a procedure to extract trouble codes from the pushbutton unit, but no way to activate the compressor before adding refrigerant.

I don't recall the procedure (but I'll try to find you a link, or type it in from reading the service manual later), but I do recall the sequence to get current-sensor values. With the key in position 2, press and hold the REST button for >5 seconds, until the left side of the display changes to a 1. Write down the right side value (with a "1" before it, so you know which value is which). Press the auto button and a 2 will appear in the left side, and write down the value in the right. Continue until you get back to "1" and post those here. Press REST again or turn the key to position 0 to cancel the test.

Since your compressor is not starting, it doesn't matter if you do the above procedure with the engine running or not.

curtis73 on Sun March 29, 2009 10:01 PM User is offlineView users profile

Here are you diagnostic numbers exactly as they appeared.

1 73
2 71
3 84
4 85
5 85
6 118
7 05
8 82
9 27
10 0.0
11 2.3
12 4.3
20 3.2
21 32
22 00
23 32
24 11.8
40 164
41 85
42 104
43 136

Ambient temps were 65-ish but the dash read 73F. Probably picking up residual underhood heat from the wife's ride home earlier tonight. Coolant temp was about 50*C according to the gauge. Engine not running

-------------------------
1966 Pontiac Bonneville
1973 Impala Wagon
1987 BMW 325 convertible
1996 Impala SS
1997 Toyota Tercel

curtis73 on Sun March 29, 2009 10:02 PM User is offlineView users profile

Sorry about the formatting on the diagnostic numbers. Let me know if you need them clarified.

-------------------------
1966 Pontiac Bonneville
1973 Impala Wagon
1987 BMW 325 convertible
1996 Impala SS
1997 Toyota Tercel

Matt L on Mon March 30, 2009 10:56 AM User is offline

#7 is the high-side pressure reading, and it is appropriate. While you may be low on refrigerant, the system is not so low as to inhibit the compressor. #5 is the evaporator temperature sensor, and it also looks about right. That's another common fault, but not on your car. You now need to check for any codes. Should have done that before, but I had to track down the procedure. It's not as easy to remember as "Hold the REST key."

Preparations for DTC readout:

Ignition ON
Temperature selector left "HI", right "LO".
Within 20 seconds, press REST and EC simultaneously for more than 5 seconds
The led in the RECIRCULATE button flashes and the display shows "di R"
Press AUTO repeatedly until all DTC's (refer to DTC table) are displayed. Record each DTC as it is displayed.
Each malfunction (short circuit, open circuit, etc.) has a specific DTC assigned to it.
The letter "E" (Error) is displayed in the left side of the display and the DTC is displayed in the right side of the display. By pressing the right AUTO button, the next DTC stored in memory will be displayed.

To erase: Only possible after all DTC's are read out. Simultaneously press both AUTO > 2 secs. "d" will be displayed in the left side of the display window and "FF" on the right side.
To cancel erase: By pressing AUTO the current faults will appear again.

Set temperature selector to normal setting.
Turn ignition OFF to end test.

DCT table:

B1226 - In-car temperature sensor (B10/4)
B1227 - Outside temperature indicator temperature sensor (B14)
B1228 - Heater core temperature (B10/1)
B1229 - Heater core temperature (B10/1)
B1230 - Evaporator temperature sensor (B10/6)
B1231 - ECT sensor (B11/4)
B1232 - Refrigerant pressure sensor (B12)
B1233 - Refrigerant temperature sensor (B12/1)
B1234 - Sun sensor (B32)
B1235 - Emissions sensor (B31)
B1241 - Refrigerant fill
B1416 - Coolant circulation pump (M13)
B1417 - Duovalve (Y21y1), left
B1418 - Duovalve (Y21y2), right
B1419 - Electromagnetic clutch (A9k1)
B1420 - Idle speed increase
B1421 - Pulse module (N65)
B1422 - Series interface (K1) connection to instrument cluster (A1)
B1423 - Switchover valve block (Y11)
B1424 - Activated charcoal filter actuator (A32m2) open
B1425 - Activated charcoal filter actuator (A32m2) closed
B1432 - Non-USA DTC
B1459 - Series interface (K2) connection to instrument cluster (A1)
B1462 - Wide open throttle (WOT) position signal: diesel engines

(http://www.benzworld.org/forums/w210-e-class/1384396-automatic-climate-control-diagnostic-trouble-code.html#post2947104)

curtis73 on Mon March 30, 2009 3:49 PM User is offlineView users profile

Ok, I'll do that as soon as the wife gets back with the car.

I have an OBD2 code reader. Would that work as well, or are these just codes that are only retrievable by the climate control?

If they can be read by the OBD2 reader, then the only thing that came up yesterday was P0600 which is a serial communication error which is sometimes associated with malfunctioning AC.

-------------------------
1966 Pontiac Bonneville
1973 Impala Wagon
1987 BMW 325 convertible
1996 Impala SS
1997 Toyota Tercel

curtis73 on Mon March 30, 2009 6:14 PM User is offlineView users profile

Ok... got the codes.

I got a B1234 Sun sensor and B1241 Refrigerant fill

Just those two.

-------------------------
1966 Pontiac Bonneville
1973 Impala Wagon
1987 BMW 325 convertible
1996 Impala SS
1997 Toyota Tercel

curtis73 on Tue March 31, 2009 5:59 PM User is offlineView users profile

Is that "sun sensor" what I think it is? The little dome on the dash that tells the AC when the sun is shining?

Jeez. I'll be there is a caviar dispenser and a bidet in it too

-------------------------
1966 Pontiac Bonneville
1973 Impala Wagon
1987 BMW 325 convertible
1996 Impala SS
1997 Toyota Tercel

Matt L on Tue March 31, 2009 9:33 PM User is offline

I would not expect a refrigerant fill code with your reading on #7, above. That's the high-side pressure in Bar. (#8 is the temperature at the dryer.) Reset those codes, press the EC button so that the lamp is illuminated, start the car, select the current-sensor mode (as in post 2 here) reading #7, then activate the compressor. The reading at #7 should do something. If it goes down, you have a restriction in the condenser or dryer. If it goes up, things are normal and you may be low on refrigerant. Or not.

There is a pressure chart in the FSM, but it advises you to not use that to determine refrigerant quantity. Rather, you charge to specs by weight, then read the charts to see if anything is too far off.

As for the sun sensor, these all fail, and it's really not worth fixing. It increases the fan speed by about 3% if the sensor is being hit by direct sunlight; you don't notice if it is not working.

Matt L on Tue March 31, 2009 9:36 PM User is offline

I just noticed that you had not found the low-side service port. It should be on the low-side line, on the left side of the engine house (driver's side). Mine has a black cap.

curtis73 on Tue March 31, 2009 10:05 PM User is offlineView users profile

Will resetting the codes let me activate the compressor? Right now it won't let me because its stuck on EC

-------------------------
1966 Pontiac Bonneville
1973 Impala Wagon
1987 BMW 325 convertible
1996 Impala SS
1997 Toyota Tercel

Matt L on Tue March 31, 2009 10:13 PM User is offline

The B1241 code will deactivate the compressor and clearing it will let it run.

curtis73 on Tue March 31, 2009 11:45 PM User is offlineView users profile

Ok, here we go with more numbers. I cleared the codes and did like you told me. I started it in EC, scrolled to #7 and it was saying 7 bar. Kicked on the compressor and it rose. Ambient temps tonight are about 60F so its blowing really cold (still hissing like mad from behind the center vents) and here are the sensor numbers. Anytime you see two or more numbers they indicate what they were the first time through the list, then the second time as things got colder/hotter. If there is just one number, it was the same both times through. Total run time was about 4 minutes.

1 = 69-67
2 = 84-93
3 = 53-42
4 = 48-40
5 = 46
6 = 181
7 = started at 7 bar without the compressor, then with the compressor on it rose to 13 and 14 at idle and 16 at 3000 rpms
8 = 130-134
9 = 30
10 = 2.0
11 = 2.3
12 = 4.3
20 = 6.7-7.3
21 = 42
22 = 00
23 = 32
24 = 13.1
40 = 164
41 = 85
42 = 104
43 = 136

So, now we're back to where we were in my last thread about hissing and cold/warm air. Do these numbers suggest anything that needs attention? Should I duplicate this test with a hot engine during the heat of the day?

-------------------------
1966 Pontiac Bonneville
1973 Impala Wagon
1987 BMW 325 convertible
1996 Impala SS
1997 Toyota Tercel

Edited: Tue March 31, 2009 at 11:50 PM by curtis73

Matt L on Wed April 01, 2009 10:49 AM User is offline

The hissing indicates low refrigerant flow, but it's really hard to tell for sure when it's that cold and the system isn't loaded.

You can try to adjust the level until the hissing nearly goes away, but I would wait until it's hotter before touching it. It's really easy to overcharge the car when looking at the pressure alone, and you won't know it until it really starts to get hot and the high side spikes (and then you won't know it if you aren't looking).

If you do decide to just add some, use pure R134a only. No oils, sealers, etc. Be sure to purge any hoses of air (or evacuate them) so that you don't inject air with the refrigerant.

curtis73 on Wed April 01, 2009 1:01 PM User is offlineView users profile

Its supposed to get in the 80s tomorrow and the wife is off work, so I'll post more sensor numbers when the car and ambient temps are hotter.

Matt... you are truly a great man. I thank you so much. Its so nice to not only have an AC forum with experts, but to have someone who knows my W210 inside and out is a HUGE bonus. Thank you, thank you, thank you.

I'm nominating you for a Golden Condenser award. I just made that up.

More tomorrow.

-------------------------
1966 Pontiac Bonneville
1973 Impala Wagon
1987 BMW 325 convertible
1996 Impala SS
1997 Toyota Tercel

curtis73 on Sat April 11, 2009 11:40 PM User is offlineView users profile

Ok, finally had a good chance to spend a few days testing while it was hot.

The other day it was 87-90 ambient. Driving down the freeway (with the sensor mode activated and on #7), it read anywhere from 09 up to 14 bar. Then all of a sudden the vents blew hot and it read 7 bar. I couldn't verify that the compressor was running, but I still heard the hissing in the dash. That could be residual pressure, but it continued to hiss the whole time which made me think the compressor was still running. Normally the hiss quits in a few seconds if I manually shut off the compressor. After about 3 minutes it started blowing cold again and the display started saying 09-14 bar again.

The same thing happened on another hot day (85+ degrees) but I was unable to access the display before it started blowing cold again.

Sounds like low refrigerant to me, but I don't know what those hi-side pressures mean.

-------------------------
1966 Pontiac Bonneville
1973 Impala Wagon
1987 BMW 325 convertible
1996 Impala SS
1997 Toyota Tercel

Matt L on Sun April 12, 2009 1:18 PM User is offline

You should usually be below 14 bar while running down the road, and especially at only 90F ambient. You do have the dual-blade electric auxiliary fan in front, right? If so, it should start on low speed at 14 bar, and stop when the high side drops to 11 bar. I don't recall the cutout for high pressure, but it's close to 30, so that shouldn't be a factor.

Almost certainly, the event where you saw 7 bar and felt hot air was the compressor shutting off. Other than too-low or too-high high-side pressure, the compressor will shut down if the evaporator sending unit (reading #5) shows freezing or an illogical value (way too hot), if the engine temperature nears 125C, or if the outside temperature drops below 3C.

Chick on Sun April 12, 2009 5:32 PM User is offlineView users profile

Ok, a little late jumping in here, but if what Matt says, the compressor shutting down, check the clutch gap..could be that simple..Should be around .02. I don't understand the "bars" only pressures..sorry..

-------------------------
Chick
Email: Chick

---------------------------------------------

Freedoms just another word for nothing left to lose

Matt L on Sun April 12, 2009 6:09 PM User is offline

1 bar is about 14.7 psi. That's the high-side pressure as reported to the climate control pushbutton unit (with 1 bar resolution). You can watch it while you drive.

Quick reference for the above:
14 bar is about 205 psi. 11 bar is about 160 psi. 7 bar is about 100 psi.

Certainly the clutch gap could be a problem, but you don't tend to see clutch problems on these cars since they are always on or always off.

Chick on Sun April 12, 2009 6:35 PM User is offlineView users profile

Just one thing to check, especially when it cools, but then goes hot when the car warms, or cycles off for whatever reason, the coil sometimes can't pull it back in until it cools down. I don't work much on mercedes, but I'd check it just to rule it out..

-------------------------
Chick
Email: Chick

---------------------------------------------

Freedoms just another word for nothing left to lose

curtis73 on Sun April 12, 2009 7:29 PM User is offlineView users profile

So far I've seen nothing to suggest that there is any external factor. I verified the temp readings on the gauge using a code scanner and a laser/IR thermometer; it never goes above 85C, even on very hot days with the AC working hard. This is something I believe to be internal with the climate control. My code scanner does real-time data, but I don't think it tells me if the AC clutch is getting 12v. That would at least determine whether or not its a clutch issue or something else. If the compressor is getting 12v but not spinning, one can assume its the clutch. If it goes hot and and the computer is telling it to shut off, I can probably assume its a sensor value parameter or a malfunctioning sensor.

I'll try viewing #5 the next time it happens and I'll get back to you.

-------------------------
1966 Pontiac Bonneville
1973 Impala Wagon
1987 BMW 325 convertible
1996 Impala SS
1997 Toyota Tercel

Chick on Sun April 12, 2009 7:34 PM User is offlineView users profile

Could be, but check the clutch gap, if for no other reason to rule it out...Just my opinion...

-------------------------
Chick
Email: Chick

---------------------------------------------

Freedoms just another word for nothing left to lose

Matt L on Sun April 12, 2009 9:30 PM User is offline

If the refrigerant is low, it is possible that the evaporator is nearing freezing temperature and shutting off the compressor. However, it did re-engage, so I doubt that the clutch is the issue; of course, it is always prudent to check.

If the system is properly charged and everything is working as it should, the compressor runs whenever the engine is running and it is over 3C outside. The compressor does not disengage with low cabin temperature; rather, the heater is used to raise the vent temperature as needed. Because it does not cycle at all during normal use, the clutch normally outlasts the car.

curtis73 on Mon April 13, 2009 5:39 PM User is offlineView users profile

Ok. So far the most obvious answer is low refrigerant. Hissing, B1241 code, poor performance... I'll get my manifold on it and see what it says one of these days. I'll post a new thread at that time because the next step will be getting help filling it

Off to read some recharging threads... Thanks guys!

-------------------------
1966 Pontiac Bonneville
1973 Impala Wagon
1987 BMW 325 convertible
1996 Impala SS
1997 Toyota Tercel

Matt L on Mon April 13, 2009 8:54 PM User is offline

The FSM agrees with what you will read in many threads on this forum: fill by weight, check pressures for verification.

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