My air conditioning problem :( - Page 2 - PeachParts Mercedes-Benz Forum

vstech · #16 02-28-2007, 08:53 PM

yup, generic reference to the screen. however, if you have a cold line on the condenser side of the receiver then you have a restriction at that point, possibly in the condenser itself. liquid refrigerant will expand downstream of a restriction causing a cooling effect. if the cool line is on the evaporator side of the receiver then all you need to do is replace it. I would not replace the expansion valve, until it is proven bad.
John

1981_300sd · #17 02-28-2007, 10:10 PM

Ok hmmm, that is interesting. Because it seems that the reciever drier is the coldest point, that and soon after. A little further on down right before it enters the car, its not hot or cold - about the same temp as the line before the reciever drier. So would that mean that I may just have a restriction on the reciever drier right?

vstech · #18 03-01-2007, 02:52 AM

yup

#19 03-01-2007, 07:31 AM

You need to attach gauges and post pressures along with ambient temperature so we can take the next step.

vstech · #20 03-01-2007, 08:41 AM

Larry, if he has cooling at the receiver, then there is a restriction there. gages are not going to tell us anything. I bet pressures will be 40 and 120 or so, depending on where the restriction is and where the head take off is. if the head take off is after the receiver, it will show 50 or so there.
John

#21 03-01-2007, 08:51 AM

Yes I agree, if it is cooling there, there is something acting as an expansion device. My goal was more to get him engaged by knowing that he will need gauges to service the system.

vstech · #22 03-01-2007, 08:51 AM

ahh, good show.
John

1981_300sd · #23 03-01-2007, 01:23 PM

I will be picking up some gauges this weekend. When I do, I will report my readings. This weekend should be about 75 degrees. At that temperature, my readings should be about 30 psi low side and about 250 on the high side, correct?

Im so lost, I went to work today, leaving the AC on, got to work, the condenser is cold, as well as reciever drier, but im not sure if thats just because it was cold outside (50 degrees).

So I guess I will wait till I get my hands on some gauges. One other question though, if I get to the expansion valve, the lines going to the evaporator should be cold right?

Thanks a bunch for everyone's help - im trying to beat the heat, as well as avoid a 2000 dollar AC bill from a mechanic.

dannym · #24 03-01-2007, 02:09 PM

Get a set of metric o-rings. The green ones and some Nylog to seal them with.
I don't know if auto part stores sell it. you can get it here:
http://www.ackits.com/merchant.mvc?Screen=CTGY&Store_Code=01&Category_Code=Nylog

They also have some good tutorials. And getting the manual won't hurt either.

I'm betting your going to have pressures like 240 high 20 low.
The thing is you want to do this right and do it right the first time. You do not want to keep doing repairs on this over and over again.
For this reason I don't agree on not replacing the expansion valve. For $15 you can hardly go wrong.

Get those pressures here as fast as you can.

Danny

tangofox007 · #25 03-01-2007, 02:21 PM

Quote:

Originally Posted by dannym

For $15 you can hardly go wrong.

I bought a cheap APA expansion valve. It leaks, and not at the pipe fittings.

#26 03-01-2007, 02:43 PM

Let's not get the cart in front of the horse. If these cold area reports are correct, the pressures will not be normal.

1981_300sd · #27 03-02-2007, 11:48 AM

Ok, my wife is on her way to go pick up the gauges now. So tonight or tomorrow I hope to find some more details about this ac issue.

One question about taking the readings:

Ive looked at many posts and tutorials such as diesel giant's write ups. My low pressure port is not where everyone else shows it is. I have one port right next to the radiator, which is vertical, and is on the side of the compressor that goes to the condenser and reciever drier before entering into the firewall.

The other line goes from the drivers side firewall, over the fuel filter and goes down right next to the primer pump down to the compressor. This line also is much larger in diameter than the other one.

From what I have learned so far, the one going to the compressor directly is the low side, and the smaller line, on the side of the compressor with the condenser and reciever drier, is the high side right?

Now if my assumptions are correct, im wondering if someone has converted it to r134 already. Because there is a large non threaded port on what I am assuming is the low side. Not like the high side which has a tire type screw in port. Would this be a retro fit adapter?

Thanks!

tangofox007 · #28 03-02-2007, 03:00 PM

Quote:

Originally Posted by 1981_300sd

From what I have learned so far, the one going to the compressor directly is the low side, and the smaller line, on the side of the compressor with the condenser and reciever drier, is the low side right?

Change the second "low side" to "high side."

1981_300sd · #29 03-02-2007, 03:47 PM

Thanks, updated

rrgrassi · #30 03-02-2007, 04:37 PM

Quote:

Originally Posted by 1981_300sd

Ok, my wife is on her way to go pick up the gauges now. So tonight or tomorrow I hope to find some more details about this ac issue.

One question about taking the readings:

Ive looked at many posts and tutorials such as diesel giant's write ups. My low pressure port is not where everyone else shows it is. I have one port right next to the radiator, which is vertical, and is on the side of the compressor that goes to the condenser and reciever drier before entering into the firewall.

The other line goes from the drivers side firewall, over the fuel filter and goes down right next to the primer pump down to the compressor. This line also is much larger in diameter than the other one.

From what I have learned so far, the one going to the compressor directly is the low side, and the smaller line, on the side of the compressor with the condenser and reciever drier, is the high side right?

Now if my assumptions are correct, im wondering if someone has converted it to r134 already. Because there is a large non threaded port on what I am assuming is the low side. Not like the high side which has a tire type screw in port. Would this be a retro fit adapter?

Thanks!

Does it look like a stubby quick connect like on an air operated tool like an impact wrench? If so, it may have been converted already.