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Massive leak from suction line connection

max2105 on Mon July 08, 2013 12:41 PM User is offline

Year: 2001
Make: Mercedes
Model: E320
Engine Size: 3.2
Refrigerant Type: R134a
Country of Origin: United States

Hi,
My vehicle has a massive leak coming from the connection of the suction line hose to the compressor. Initially both HIGH and LOW pressure gauges read zero. I replaced the O ring on the suction line hose to air compressor (it looked bad) and then performed a leak test, which passed. Then I replaced the receiver/dryer and leaked checked again. No leaks. This is what I did:

1.Evacuate the system by attaching the red hose to the high side; blue hose to the low side; and yellow hose to the vacuum pump (no problems).
2.Open both dials on the A/C manifold gauge set (no problems).
3.Start the evacuation process by applying a vacuum until it reaches 29.9 inches. This may take 30 minutes. Close both dials on the A/C manifold. Turn pump off and make sure vacuum holds for 10-15 minutes to make sure there are no leaks in the system (no problems).
4.Once system tightness is confirmed, remove vacuum and allow air to enter once again (no problems).
5.Replace receiver/dryer with a new one. Lubricate threads with mineral oil. Replace all 4 “O” rings (no problems).
6.Open both dials on the A/C manifold gauge set. Apply vacuum once again but this time for at least a couple of hours to make sure all moisture in the system is boiled out (no problems).
7.Close both gauges and make sure vacuum holds for at least 30 minutes (no problems).
8.With both dials closed, remove the yellow center charging hose attached to the pump and attach it to the R134 can (no problems).
9.Slowly inject a bit of R134 to evacuate air in hoses (no problems).
10.Open the red high side dial and invert the R134 can to apply refrigerant in the liquid state. Apply at least one 14 Oz can (as I was finishing applying the first can, both gauges were pressurized and all of the sudden a loud leak was heard from the "compressor area." I was able to determine that as I moved the suction line hose (compressor end) the leak got worse/better).
I don't know if the hose itself is bad (no visible tears or cracks) or the compressor failed.

As an FYI, three years ago I replaced the AC compressor (Nippon Denso made in Japan), the AC condenser, the AC expansion valve and the receiver/dryer. I also thoroughly flushed all hoses. The AC worked great for three years until this sudden failure.
Any ideas?
Your help is appreciated!

Sergio

Never got to these.....
11.Close the red high side dial.
12.Start engine and turn A/C on at full blast
13.Open the blue low side dial and apply refrigerant in the gas state (a little at a time)
14.Recharge the system using the manifold gauges to verify proper pressures using the R134a Pressure-
Temperature Relationship chart.
15.When you add refrigerant, add some then close the manifold valve and wait a minute for the system to stabilize before reading the gauges. Keep adding refrigerant very slowly until proper pressures are obtained.
16.Try to force heat build-up and check that the aux fans turn on when high side reads about 230 P.S.I.

Jag987 on Mon July 08, 2013 3:37 PM User is offline

Once upon a time, I had replaced a hose, o-tube and drier on a car. It held vacuum for a long time so I started refilling it and could almost instantly hear a leak. Turns out eh the o-ring on the drier was the wrong size. somehow under vacuum, it got pulled and sealed. under even a little positive pressure, it pushed out and started to leak. Make sure you have the right size o-ring installed and it is in the right place. I have replaced more hoses for leaks than o-rings, but anything is possible.

-------------------------
I bought a can of 134a at w**-mart that had a stop leak, oil, and dye in it. It also had a hose and a gauge, so now I'm an AC pro!

max2105 on Mon July 08, 2013 4:26 PM User is offline

Thanks. I'm sure I replaced the O ring in the suction hose with the correct size but I will double check the installation. Why would the high pressure bleed into the suction hose with the engine/compressor off?

Jag987 on Mon July 08, 2013 6:30 PM User is offline

Most systems will equalize pressure between the two sides when the system is turned off. Find a system that works good and hook up your gauges, depending how accurate they are, they should both read the same.


-------------------------
I bought a can of 134a at w**-mart that had a stop leak, oil, and dye in it. It also had a hose and a gauge, so now I'm an AC pro!

max2105 on Tue July 09, 2013 8:02 AM User is offline

OK. So the consensus is that it is a bad suction hose and not the compressor? I noticed there is play in the connection between the suction hose and the compressor even when the screw is tightened all the way.

mk378 on Tue July 09, 2013 8:27 AM User is offline

First, apply a little more pressure and find exactly where the leak is.

>I noticed there is play in the connection between the suction hose and the compressor even when the screw is tightened all the way.

You may have the wrong part then. A "pad" connection should go all the way down to having the two flat metal surfaces touching. Test-fit without an o-ring. If it fits all the way down just by hand, someone may have replaced the bolt with one that is too long.

Edited: Tue July 09, 2013 at 8:29 AM by mk378

GM Tech on Tue July 09, 2013 8:27 AM User is offline

Correct bolt? too long replacement bolt??? don't force it- you'll chance cracking the casting-- right o-rings/sealing washers?

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

max2105 on Tue July 09, 2013 10:11 AM User is offline

Thanks. It is the correct bolt for sure since I'm the only person who did work on this car. The two metal parts touch e/o and seem to fit just fine. I bought a new O ring using the manufacturer PN and it matches the old one's dimensions. I lubricated the O ring with PAG46 oil and then inserted the hose into the AC compressor. Then tightened the only bolt. The bolt is to one side of the coupling and when the entire coupling is moved, I notice it has a bit of side to side play.
Is there a gasket maker/sealant I can use between the two metal surfaces to ensure this connection is leak tight? Or maybe I can put a washer on the bolt to make a tighter connection?

max2105 on Tue July 09, 2013 10:11 AM User is offline

Thanks. It is the correct bolt for sure since I'm the only person who did work on this car. The two metal parts touch e/o and seem to fit just fine. I bought a new O ring using the manufacturer PN and it matches the old one's dimensions. I lubricated the O ring with PAG46 oil and then inserted the hose into the AC compressor. Then tightened the only bolt. The bolt is to one side of the coupling and when the entire coupling is moved, I notice it has a bit of side to side play.
Is there a gasket maker/sealant I can use between the two metal surfaces to ensure this connection is leak tight? Or maybe I can put a washer on the bolt to make a tighter connection?

max2105 on Tue July 09, 2013 10:11 AM User is offline

Thanks. It is the correct bolt for sure since I'm the only person who did work on this car. The two metal parts touch e/o and seem to fit just fine. I bought a new O ring using the manufacturer PN and it matches the old one's dimensions. I lubricated the O ring with PAG46 oil and then inserted the hose into the AC compressor. Then tightened the only bolt. The bolt is to one side of the coupling and when the entire coupling is moved, I notice it has a bit of side to side play.
Is there a gasket maker/sealant I can use between the two metal surfaces to ensure this connection is leak tight? Or maybe I can put a washer on the bolt to make a tighter connection?

max2105 on Tue July 09, 2013 10:13 AM User is offline

Something's going on with my PC; sorry for the multiple replies...

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