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Discussion Starter #1
Ok folks, so on this warm day in NJ, my climate control was set to 68, and the A/C kicked on. Mind you it hasn't been on for a while, so this was the first time in a while that the compressor was spun.

I wanted it a bit warmer, so I went up to 70, and the a/c shut off. I restart the car and get the dreaded EC light staying on.

Here are the results of the test:

1-69 (inside temp)
2-53 (outside temp)
3-118 (left heater core)
4-120 (right heater core)
5-60 (Evaporator Temp)
6-186 (engine coolant temp)
7-03 (refrigerant pressure)
8-76 (refrigerant temperature)

Codes:

234 (sun sensor. Does anybodies work? haha)
241 (Low refrigerant)

Now, the a/c diagnostic site recommended that I replace the refrigerant temp and pressure sensors, and recharge the A/C.

Here are my questions:
1. Is there any way to tell if its a bad sensor or low refrigerant
2. Why would the refrigerant be low? Only a leak would cause a decrease in refrigerant, right? Where might this be leaking from?

3. Has anybody replaced the above sensors? if so, could you give me a step by step.

Rebuilding an engine is no problem, but this is my first foray into the A/C process.

Thanks,
Oliver
 

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That pressure

is low even for a variable by demand system like the mercedes.So since the compressor shut down(the ec light is on)Most likely the r134a is low.Remedy that and the light will go out and the codes will clear.A few places where it can leak from,fittings hoses etc but the only way to find them are a dye kit and black lamp,or a sniffer.The dye kit is messy.The sniffers are pricey.If you are up for either go at it.If not any good ac shop will track it down for a price.Fix the leak ,recharge the system and you are good to go .:thumbsup:
ohlord:bowdown:
 

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Hey, Oliver.

It is important on any car to spool up the compressor periodically as this helps prevent seal deterioration. Most of us that is not a problem, either because we just leave it on auto or we have the defroster on, etc. Probably does not apply to you, just throwing it in for others reading the thread.

A known area for leaks on the 210 is the condenser and it is not a tough job to replace, G-AMG did a great DIY and it is in the sticky. Toss in some dye and if you don't see it around fittings, etc. (be sure to look closely behind the compressor pulley) then inspect the condenser--very, very closely. Leaks in the condenser are microscopic and much harder to spot than those in seals, hoses and fittings. If you simply cannot find it then I would be inclined to replace the condenser. If you do it yourself you would still be money ahead over a shop diagnosis. Whatever you have to replace, buy the part in advance and do not leave the system open to the atmosphere very long or you also get to buy a receiver-dryer. After the fix have the system evacuated and recharged.

Take care and enjoy the ride,
Greg
 

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Discussion Starter #4
Thanks greg and rob.

I reset the codes, and I'll see what happens when the weather gets warmer.

Ec light is now off, but it was too cold to get the compressor to kick over, so it'll have to wait.

I don't see why it would start leaking all of a sudden, but if I recharge it in the summer and it keeps happening, I'll toss in the dye.

thanks.
 

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Thanks greg and rob.

I reset the codes, and I'll see what happens when the weather gets warmer.

Ec light is now off, but it was too cold to get the compressor to kick over, so it'll have to wait.

I don't see why it would start leaking all of a sudden, but if I recharge it in the summer and it keeps happening, I'll toss in the dye.


thanks.
Hey, Oliver. Cold or not the compressor is triggered when you engage the front defroster mode. If the mode won't engage or the EC light stays on them you know the problem continues.:)

FWIW it has probably been leaking very slowly for a long time (especially if it is the condenser), the level just finally got low enough to trigger the problems.

Take care and enjoy the ride,
Greg
 

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The compressor does not come on with the defroster as in other cars. It runs whenever the outside air and evaporator temperatures are both above freezing (actually about 37F, IIRC) unless the climate control is switched off. If it is below freezing out, the compressor does not run, regardless of the setting.
 

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Discussion Starter #7
ok kids, heres the deal. I bought a can of refrigerant (HFC-134a) only, no dyes or stopleak.

I also bought the hose with the gauge.

When putting the gauge on, it shows 90psi with the engine off.

This is on the low pressure port.

That on the gauge indicates that the system is full.

Yet the EC light is on.

what gives?
 

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That should be enough to start the compressor, assuming that you still read 3 or so on #7 in the current-sensor mode. Did you clear the trouble codes before? B1241 will prevent the compressor from operating until it is cleared.

Once you have cleared the code, run the air conditioner panel in current-sensor mode and monitor #7 as you start the compressor and drive the car. If this reading drops too low while driving, it will trigger B1241 and shut down. With a sufficient charge, two things can cause this reading to drop: a bad sensor, or a restriction (in the condenser or receiver/dryer).
 

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Did

you turn the a/c on and both control to lo and fill it running?
:bowdown:eek:hlord
from all the previous readings it still looks like you are just low on r134a and the leak needs to be located.
Electronic sniffers that are ultra sensitive are only about 60 bucks at harbor freighttools or since it needs to be located and fixed which entails a evac of the system a new drier and refill with the proper wt. of lube oil and r134a.It may be easier to take it to an indie a/c guy.
:bowdown:
 

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Discussion Starter #10
ok, so I started the car, cleared the codes, and checked the low press. port again. It read about 32psi. I figured that was a touch low. I hooked up the 134 can, and within about 2 seconds of opening the can, it jumped for 32 to 50 and held there. The compressor was most certainly turning.

After doing this, I checked the pressure reading, and it was 13. with the temps set to about 66.

Ambient temp was about 74.

How is that reading?
 

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13 bar with an ambient temperature of 74 sounds too high, but I don't have the chart sitting right in front of me. I'll try to get a chance to look at it later.

50 psi on the low side with the compressor running is certainly too high. You should not be above 40.
 

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The EC indicates the compressor not running, but requested to do so, on my 01, got it twice once it was a sensor, they drained and measured what came out, the second time it was a bad hose, drain replace, recharge under waranty.
 

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Clear the

errors.Run the tests again.Is it cooling now(should be if comp is running)what are the values and errors.
or is it good to go until the fluid leaks out again?:eek:
:bowdown:
 

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I

meant is the system cooling?At least until it leaks out of the system again,not out of the can:thumbsup:sorry for the confusion:)
:bowdown:
 

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Discussion Starter #16
right, no the system is cooling.

My point with the can was that since very little went in, I can't imagine that a lot is leaking from the car.
 

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Got ya

so clear the errors and run the numbers for the sensors and errors and look at the pressure value.Normal operation varies between 7-19 on a balmy 80f day at Lake Hopatcong:thumbsup:
:bowdown:
 
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