Anyone ever see a bad epansion valve/ symptoms?
I just did some homework on the pressures and temps according to the MB cd and mine are off with correct amount of freon. 91 300E with R-12 that was just evacuated, flushed and recharged at an MB independent shop.

MB spec: Ambient 104 F / 40% Relative Humidity, High Blower Speed=
Low side 29-36 psi High side 377-391 psi Duct temp 55-60F.

Actual readings 105 ambient/ 25% RH, Low side 45-47psi High side 220-235 psi and 80-83F duct temp. That is with the front fans on high and helper fan.
Noticed last night that the guages will slowly fluctuate about 10 to 20 psi. the high side will go up 20 while the low goes down 8 or 10 at the same time, then they go the other way and over and over but like 3 or 4 times a minute.
This morning it was 86F ambient 38% RH on the way to work and on low it only blew 65F....same as when it was 105F yesterday. So Im wondering if the expansion valve is limiting the freon to the evap to 65F on low blower or any blower for that matter , or if the evap is dirty and clogged on the outside, but it blows hard.

normally, I wouldn't throw money at a situation....but an expansion valve costs next to nothing...if you can have someone evacuate and recharge....

just make sure you replace the o-rings.... common leakage problem at the expansion valve....

i think the part is about 30 dollars.

__________________
1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


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Yeah, its $21.02 for the valve. Hell, only another $50 for the R-Dryer.
Lucky for me this place is in PHX.
www.***************

with all due respect to Fast Lane... I have used ********az for a majority of my needs... they are incredibly inexpensive

__________________
1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


[/SIGPIC]

That doesn't really look like a bad expansion valve to me although it could be partially open causing such pressures.

It looks to me more like a weak compressor. Niether one of these scenarios would be very common at all. The only thing that usually happens to the TXV is that it leaks on top at the diaphragm. The compressors usually work or they have catastrophically failed.

I have had a similar expansion valve fail open on another make car and it gave hardly any difference in pressure at all. When they fail in function, I think it is more common for them to pinch off and actually draw the low side into a vacuum.

Hope this helps somehow,

Hmmmm, well I know that if I turn off the fans the high side will go right up to 450 or so, so I know the compressor can compress. Im just about ready to say screw it and replace the valve........after I have a look at the evap surface.

hello ,

thanks for your suggestion this is really helpfulll or informative for me thanks again

thanks and regards