Hey,
What exactly does this part do?

From information I got from a search this may be causing AC problems for me.

Thanks

Danny

Danny
maybe you can tell us more about your problem with a\c system first we need to know years & model of the vehicle.

__________________
MB STARS Master Guild Technician,17 years MB tech
14 years independent shop owner

Sorry, forgot.

I have a 1984 300SD.

I have been having problems with the AC since I bought the car. I put a can of leakstop in and it seamed to work but the pressures are way off.

I get over 300lbs on the high side with 45lbs on the low side. That is the only way I can get it to cool.
If I drop the low side down to 30lbs it will take the high side down to about 270, but it won't cool hardly at all at that pressure.

Also, the compressor runs continuously, it never stops.

I did notice some oil on the TEV valve if I can't tighten it I will replace it but I think the ETR valve may be causing problems also.
I guess I should just replace that too at the same time. They are both fairly cheap to purchase on line.

Thanks

Danny

Sounds like you have a blockage in the expansion valve. Your eveporator is not getting cool so the AC control is telling the compressor to stay on. This in turn is causing the high pressures and the low pressures are being caused by the lack of freon getting by or to the evaporator. What is causing the blockage we will need more info. Leak stop? Why?. Was the compressor Ok or has it trashed itself and the debris is blocking the expansion valve?
We will need more info. What have you done and what have you added to the system.

Dave

__________________
1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car

Hey,
I agree with your blockage assesment. That's exactly what I was thinking.

I put the leakstop in because there was a leak. I didn't notice it was the expansion valve until yesterday when I was removing the instrument cluster.

The compressor has always worked fine it just doesn't shut off. The previous owner had a service ticket concerning the AC. All they did was pull a vacuum and recharge though. The ticket doesn't say they did anything else.
Don't worry I won't be going to them for repairs.
Anyway, these AC problems aren't something new, i'm just more active in getting to the problem and making a final fix.

Once in a while I can hear the TEV valve spit out some refrigerant into the evaporator. It's just a short hssing sound.

I was wondering if the ETR valve would cause problems like this also but i guess if I'm replacing the TEV then I'll just replace the ETR valve also.

Thanks

Danny

Perhaps you have a blockage but I would think that your low side would go into a vacuum state if the expansion were truly blocked. High side would go up but if the refrigerant was blocked then there is little, or not getting past the blockage. Maybe some other times need to be examined prior to jumping into an expansion valve replacement.

Have you checked?
Mono-valve (split rubber seal on insert)
Mon-valve (electrical control, grounded through pushbuttons)
A/C comp (Always on, regardless OR with A/C demand)
ETR (quite possible IF A/C demand-comp runs continuous)

Let's explore some of these other contributing factors to determine if there is pressure issue to address.

BTW: Was the A/C system converted to R-134?