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Old 04-29-2010, 12:10 PM   #1
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A/C will not take any more refrigerant - cannot fill to spec

01 CL600. Car bought in winter. AC never worked. Just getting around to fixing it now because it wasn't necessary before.

Vacuumed out all old refrigerant, tried to put in some new R134. It took a can and a half, but not enough to spec. I put it in the low side. Now it's stuck at 6-7 bar of pressure, and if I try to put any more in it just won't take it. When I touch the hoses I don't feel any flow through the low or high. I can see the (torque limiter) shaft turning on the compressor. No, the "EC" button is not on, though after a while it will be forced on and will throw the code "refrigerant low". Low side has same pressure as high side. Both hi and low indicate about 75 psi. I hear some rattling in the area, not sure if it's from the a/c compressor or power steering pump (ABC tandem pump). I manually engaged the compressor through diagnostic computer and it still won't suck any more freon into the low side.

Is my compressor bad?
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Old 04-29-2010, 12:27 PM   #2
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Originally Posted by ch33sehead View Post
01 CL600. Car bought in winter. AC never worked. Just getting around to fixing it now because it wasn't necessary before.

Vacuumed out all old refrigerant, tried to put in some new R134. It took a can and a half, but not enough to spec. I put it in the low side. Now it's stuck at 6-7 bar of pressure, and if I try to put any more in it just won't take it. When I touch the hoses I don't feel any flow through the low or high. I can see the (torque limiter) shaft turning on the compressor. No, the "EC" button is not on, though after a while it will be forced on and will throw the code "refrigerant low". Low side has same pressure as high side. Both hi and low indicate about 75 psi. I hear some rattling in the area, not sure if it's from the a/c compressor or power steering pump (ABC tandem pump). I manually engaged the compressor through diagnostic computer and it still won't suck any more freon into the low side.

Is my compressor bad?
Sounds to me like a bad compressor. Could also be a plugged evap dryer that is not allowing the refridgerant to circulate. If the system was empty or close to empty that shouls be changed as a matter of course anyway.
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Old 04-29-2010, 01:24 PM   #3
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If I vacuum out again, replace drier, and that doesn't solve the problem, can the same drier be used again after I replace compressor? Or should I go straight to replacing the compressor? Thanks for your response.
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Old 04-29-2010, 01:38 PM   #4
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If I vacuum out again, replace drier, and that doesn't solve the problem, can the same drier be used again after I replace compressor? Or should I go straight to replacing the compressor? Thanks for your response.
Seems you may not have the required equipment to do the job correctly. Believe the evap/dryer is soldered in place and do you have a complete set of gages?? Temperture compensation charts?? Just dumping in a can of the stuff does not cut it. Equipment to leak check?
My suggestion to you is to take it to a GOOD airconditioning shop that works on MB's and have it at least diagnosed. Then make a decision as to how you want to proceed. Just throwing parts and your time at it without knowing whats actually wrong is not the way to go about this. The money to do this will be well spent
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Old 04-29-2010, 01:53 PM   #5
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Pressure gauges I have. Temp I can read through diagnostic computer from sensors already in place in the system. Drier is bolted on - can be easily replaced. By evap/dryer I assume you mean the accumulator that attaches to the condenser.
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Old 04-29-2010, 02:01 PM   #6
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Pressure gauges I have. Temp I can read through diagnostic computer from sensors already in place in the system. Drier is bolted on - can be easily replaced. By evap/dryer I assume you mean the accumulator that attaches to the condenser.
You seem to be having difficulty finding out exactly whats wrong. You have a set of the dual gages and valves used to work on refridgeration?? You have the temp conversion chart ?(not just the temp thermometor) You have the leak check equipment? The evap/dryer may be bolted to the car but I believe its soldered in to the refridgerant line. There is no accumulator that I am aware of. My final suggestion is what I said before have it professionally diagnosed and then make a decision. By the way, Compressors are quite expensive. Not trying to be funny or sarcastic but seems that you have enough knowledge to be a bit dangerous and thats not going to resolve your issue.
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Old 04-29-2010, 03:21 PM   #7
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Just a minor point. Accumulators are used with Orfice tube pressure regulators and Receiver/Dryers are used with Thermal Expansion Valves. Their function is pretty much the same -- keep liquid refrigerant from reaching the compressor. People tend to use the two terms interchangeably.
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Old 04-29-2010, 03:36 PM   #8
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Just a minor point. Accumulators are used with Orfice tube pressure regulators and Receiver/Dryers are used with Thermal Expansion Valves. Their function is pretty much the same -- keep liquid refrigerant from reaching the compressor. People tend to use the two terms interchangeably.
OK but the evap/dryer also removes any moisture from the system and thats why it must be changes whenever the system is opened or contaminated. Does the accumulator do that also??
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Old 04-29-2010, 08:48 PM   #9
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OK but the evap/dryer also removes any moisture from the system and thats why it must be changes whenever the system is opened or contaminated. Does the accumulator do that also??
Yes, definitely change the drier if the system has been running without a charge or a conversion from R12 to R134. As far as I know the accumulator does not have a drying/cleaning function just accumulates the liquid refrigerant.

I agree with the advice to see a A/C tech for almost everyone with A/C issues. It's not really a very good candidate for DIY. Just having a set of gauges isn't much good unless you understand the principles. And considering the high side pressure you'll be in for a surprise if you guess wrong.
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Old 04-29-2010, 09:01 PM   #10
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Yes, definitely change the drier if the system has been running without a charge or a conversion from R12 to R134. As far as I know the accumulator does not have a drying/cleaning function just accumulates the liquid refrigerant.

I agree with the advice to see a A/C tech for almost everyone with A/C issues. It's not really a very good candidate for DIY. Just having a set of gauges isn't much good unless you understand the principles. And considering the high side pressure you'll be in for a surprise if you guess wrong.
Agree with you. This is no DIY and from what I read I do not think he has a clue as to how to go about diagnosing and repairing this issue. Wonder what the rest of the car is like?? He knew the A/C was inop when he bought it and he waited till now to play with it. He should turn the whole thing over to a good A/C shop that is familiar with MB's.
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Old 05-04-2010, 09:31 AM   #11
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If the expansion valve has failed closed you will be able to pull a vacuum but not able to fully fill the system. I normally use the first can with vacuum as a wet fill. The rest are gas fill.

I suspect the expansion valve is defective. This can be seen with gauges indicating very high, high side pressures and close to normal low side.
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Old 05-08-2010, 11:22 AM   #12
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if your gauges read the same pressures and your compressor is on the reed valves are bad and you need a compressor also go ahead and put in a expansion valve in and inspect it for debris when you pull it out and a drier if you find debris flush the suction line and the evaporator so it does not happen again

Last edited by mbwhat; 05-08-2010 at 01:13 PM.
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Old 05-08-2010, 11:22 AM
 
 
 
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ac, add, cans, car, completely, dual, fill, freon, high, low, pressure, put, refrigerant, side, system



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