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

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.

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,

------------------
Larry Bible
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

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).]

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,

------------------
Robert W. Roe
1984 300SD 170K mi

My car is a 1986 190 2.3-16, W201.034. Do you know if the expansion valve might be different? Thanks, Joe

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.


------------------
Bill Wood - Webmaster
MercedesShop.com, LLC

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.


------------------
Bill Wood - Webmaster
MercedesShop.com, LLC

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.

------------------
Robert W. Roe
1984 300SD 170K mi