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  #1  
Old 06-04-2000, 12:15 PM
Joe-1
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Exactly what is the function of the expansion valve on the a/c system do? Are thee different valves for r-12 and r-134a or is the same one used for a retrofitted car?
Thanks, Joe
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  #2  
Old 06-04-2000, 01:35 PM
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Join Date: Feb 2000
Location: Rancho PV, CA, USA
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The expansion valve allows the compressed refrigerant to be released into the cooling coils in the airconditioning system. This action drops the pressure creating the cooling effect. I do not know if they have to be changed on conversion to R-34.
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  #3  
Old 06-04-2000, 03:21 PM
LarryBible
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Joe,

These are typically not changed during conversion. You did not say what model car you're talking about.

On most models you ideally will change the pressure switch(s).

Good luck,

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Larry Bible
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles
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  #4  
Old 06-04-2000, 05:29 PM
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Although the part number remains the same, R-134a expansion valves have a different calibration than R-12 valves; this calibration difference can affect system performance. If you are converting from R-12 to R-134a, then by all means, switch to the R-134a expansion valve. Its inexpensive and will lessen the possibility of having to go back in for additional repairs due to an expansion valve leak.

If you have a W124 vehicle with R-12 and a leaky expansion valve and wish to stay with R-12, then you'll have to look aftermarket for an R-12 valve. M-B currently only provides R-134a calibrated expansion valves for the W124. I believe the same holds true for other models (e.g., W123, W126).

Does it make a difference? Depends on your ambient conditions. In the deep South, where M-B A/C systems can be easily overwhelmed by summer's heat and humidity, most definitely yes. I've been in R-12 vehicles equipped with R-134a calibrated exp. valves and A/C cooling was less than optimal. Subsequent installation of R-12 calibrated exp. valves greatly improved system performance.

[This message has been edited by jgl1 (edited 06-04-2000).]
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  #5  
Old 06-05-2000, 02:53 AM
Robert W. Roe's Avatar
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Can someone tell me if this part number, 1268300384, is correct for an R12 or R134 expansion valve?

My repair shop gave me an estimate for $55 for one of these parts, 4 new "O" rings, 3 lbs. of R12 @ $45 each, and $150 labor to get my AC working. Total $342 + tax. I'm probably going to get the work done, but now, besides the question of whether this is a good price, I wonder if the replacement part will be correct? I do like cold AC and I do travel south at times. Thanks in advance,

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Robert W. Roe
1984 300SD 170K mi
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  #6  
Old 06-05-2000, 11:12 AM
Joe-1
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My car is a 1986 190 2.3-16, W201.034. Do you know if the expansion valve might be different? Thanks, Joe
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  #7  
Old 06-05-2000, 03:05 PM
Bill Wood's Avatar
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quote:
Originally posted by Robert W. Roe:
Can someone tell me if this part number, 1268300384, is correct for an R12 or R134 expansion valve?


That is the correct part number. $55.00 is list price for that part...it is considerably less in PartsShop.


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  #8  
Old 06-05-2000, 03:14 PM
Bill Wood's Avatar
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quote:
Originally posted by Joe-1:
My car is a 1986 190 2.3-16, W201.034. Do you know if the expansion valve might be different? Thanks, Joe

The correct part for your car is 201 830 06 84.
Submit a Parts Information Request in PartsShop for the latest pricing and availability.


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  #9  
Old 06-06-2000, 08:17 PM
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Thanks for the reply, Bill. I'd love to save some $$, but I lack the know-how, freon license, or the tools to do this type of work myself. I doubt whether my shop would honor their one year warranty on repair work if I brought my own part, and considering the $135 for R12 (ouch!) and the $150 labor charge, I was just wondering whether the part number is correct for the R12.

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Robert W. Roe
1984 300SD 170K mi
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