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R107 W110 R170 W202
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Discussion Starter #1
My aircon does not make cold. I have spent $$ to get is regassed and it still does not make cold. Slightly cool only.

I would like to get an idea myself, before I have wreck the car because of the cost to get this fixed.

Here are the high,low pressures at rest, engine off, 24degC /75F.
 

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R107 W110 R170 W202
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Discussion Starter #3
This video shows the inspection glass during operation
 

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Discussion Starter #4 (Edited)
Lastly,
A heap of green oil spluttered out of the gauge manifold and hoses when I slowly released the pressure and disconnected the hoses.
Is that normal?
 

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1998 C280; 1987 560SL
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Lastly,
A heap of green oil sluttered out of the gauge manifold and hoses when I slowly released the pressure and disconnected the hoses.
Is that normal?
What type of refrigerant. If it is 134A, I would say it appears to be low charge. 150 on the high side would be a little low, although at 75 F it would be a little lower. Still I would think the high side should be above 200. What does it read before starting? Green stuff is oil and is normal.
 

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Here are the pressures after some minutes of engine and aircon operating at idle.
normal pressure running is around 40 low side , 250 / 300 high .at rear of compressor there are 2 pipes , one get HOT the other COLD .is the cold one nice and cold ?? .looking at your pressures , the system is half empty . when you read the pressures on a cold engine not running , usually you see around 80 psi .
 

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Discussion Starter #7
normal pressure running is around 40 low side , 250 / 300 high .at rear of compressor there are 2 pipes , one get HOT the other COLD .is the cold one nice and cold ?? .looking at your pressures , the system is half empty . when you read the pressures on a cold engine not running , usually you see around 80 psi .
The engine was not cold. It had been running a bit before I tested this.
 

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1997 C280
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In your first photo, if you have the proper amount of refrigerant, it is about 50 PSI at both low and high, which means equal pressure in the entire system, therefore your compressor is not working. Most likely the clutch is worn out and slipping. Suggest you replace the compressor.
 

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1999 E430; 2005 ML500
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It looks to me like your compressor is working. Of course the pressures are the same when the engine is off. You won’t hit 250 on a 74 degree day. As you can see here, high-side pressure will be roughly 5x low-side with a functioning compressor


Green goo could come from leak-check dye, which is really just oil. If it’s truly gooey, then someone once put in some stop-leak gunk, which may have clogged the expansion valve or other parts.

Does the Ac seem to work when you’re traveling at speed?
 

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I should add that when revving the engine to about 2500 to 3000rpm, the pressures look like this.
High side is over 200 then. But still not making cold.
look at the drier sight glass , i ll bet you see a lot of bubble going thru .a small amount is of , but not a large amount .looking at the gauges , the low and high side are too low .with the a/c off , is air coming out of vents at near outside temp .just making sure heater is off .how cold is the pipe coming out of compressor [ low side ]
 

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2003 C320 coupe, 2000 ML320
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Have you checked your duct flaps/doors ?... Easy way to see if AC/heat door is working,.. bypass heater core.. take temp readings at vents.. before and after bypass....
 

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Have you checked your duct flaps/doors ?... Easy way to see if AC/heat door is working,.. bypass heater core.. take temp readings at vents.. before and after bypass....
no heater / a/c door , both in same box .if you think heater core is stating warm , just pinch heater hose off , from pressure readings , he is low .if you hand feel the low side pipe at rear of compressor , it should be icy cold .i ll bet its not .a easy test is to add some 134 to it .
 

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1995 C220
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There are a lot of unknowns here. First thing that should be asked, is was the system vacuumed and did it hold a vacuum before you charged it? If not, there is air in the system that is keeping it from getting cold. The numbers on your gauges will be the same when not running. Your running numbers will fluctuate depending on the ambient temps. You can google charts on what they should be, but that doesn’t concern me so much. If you have one line getting hot, and one line getting cold, you are moving freon. I would definitely check your blend doors. You need to get a vacuum tester and make sure the doors are operating properly. There are plenty of diys in this forum that you can search for. Your sight glass video shows air bubbles, so it may not be 100% full, but I wouldn’t add any more til you are sure the doors are operational.
 

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Discussion Starter #15
thanks for all the kind help!

The aircon has NEVER made proper cold since I have this car (9 years).

I had it recharged recently as the guy said it was about empty. He said he did evacuate it and charged it with proper new R134a.

Thereafter, it made slightly more cool and one can now see green fluid passing in the inspection glass.
But still not cold cold.



Can those flaps you mentioned stop it making cold even when the engine has not yest warmed up (heater not operational yet?
Where in the W202 would they be located?

I am not sure what to do next.
 

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thanks for all the kind help!

The aircon has NEVER made proper cold since I have this car (9 years).

I had it recharged recently as the guy said it was about empty. He said he did evacuate it and charged it with proper new R134a.

Thereafter, it made slightly more cool and one can now see green fluid passing in the inspection glass.
But still not cold cold.



Can those flaps you mentioned stop it making cold even when the engine has not yest warmed up (heater not operational yet?
Where in the W202 would they be located?

I am not sure what to do next.
the doors / flaps have nothing to do on this car , the heater output is controlled by the heater valve cycling on / off .the answer to your problem is to feel the larger pipe at rear of compressor , is it nice and cold , or not .that is the second thing you look after looking at pressures , and also site glass .the green stuff you see is leak test dye .all a/c on older cars leak .the worse problem is a bad evaporator .if you dont answer those questions , waiting time .
 

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Discussion Starter #17
the doors / flaps have nothing to do on this car , the heater output is controlled by the heater valve cycling on / off .the answer to your problem is to feel the larger pipe at rear of compressor , is it nice and cold , or not .that is the second thing you look after looking at pressures , and also site glass .the green stuff you see is leak test dye .all a/c on older cars leak .the worse problem is a bad evaporator .if you dont answer those questions , waiting time .
Thank you.
Ok.
Tested today after 25min drive with aircon on.
Low side pipe near compressor is NOT cold. Not hot but maayyybeee a little cool. Cold, no.
High side pipe is quite hot.
Sight glass looks like in the video link I posted further up.

Given everything so far, where does that put the likely problem?
Regards
Bernt
 

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Thank you.
Ok.
Tested today after 25min drive with aircon on.
Low side pipe near compressor is NOT cold. Not hot but maayyybeee a little cool. Cold, no.
High side pipe is quite hot.
Sight glass looks like in the video link I posted further up.

Given everything so far, where does that put the likely problem?
Regards
Bernt
i would add some 134 in there and see .the gauges pressures are too low .
 

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Discussion Starter #19
I have ordered a tin of it. How much should I add to start with?
What pressure doe I need to archive for this system?
 

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2002 Mercedes Benz ML320
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First if your a/c system is full of moisture you won’t have cold air conditioning because A/C is dry cold not wet cold like a swamp cooler. That being said I always replace the receiver dryer and expansion valve on all Benz, as well as doing a thorough leak detection because the “gas” or otherwise known as R134A will seep out of any defective hose or O rings.
 
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