How to fix AC Freeze?

Last spring my evaporator sprang a few leaks. It is in the middle of the dash. They had to take the whole front of the car apart to replace it. (I think it was the evaporator - something like that anyway.) It
cost $1,800 US to do it, less than half of what Ole Heavy Karl the local Stealership would have charged. But now when I have driven for anywhere from an hour to two or three hours, the air gets warm coming out of the AC vents and I have to turn it to the no-compressor setting for a long while. Then eventualy I can get it to come back on. One excellent inhabitant of this ng suggested it is coil freeze-up. Is there any way to fix this? If not, I will have to sell it or give it away and try to find a new car to replace it. But that is bad cause the new S Klasse only has the humongous 550 cc gas eater available. And I fear the return of gas lines like the 70s in Ca. So I won't buy the new 5.5 L engine which means I will have to go to the Rexus LS430 Kudzu Kar. Suggestions to fix the AC problem? The professional wrenchs at Smilin Sams will fix it, of course, but the head guy didn't seem to have any ideas when I called him when it happened.
mcbrue thankfullinadvancely under the bridge in the trailer down by the river
96 S420
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1. mcbrue Jan 23, 7:01 pm Last spring my evaporator sprang a few leaks. It is in the middle of the dash. They had to take the whole front of the car apart to replace it. (I think it was the evaporator - something like that anyway.) It cost $1,800 US to do it, less than half of what Ole Heavy Karl the local Stealership would have charged. But now when I have driven for anywhere from an hour to two or three hours, the air gets warm coming out of the AC vents and I have to turn it to the no-compressor setting for a long while. Then eventualy I can get it to come back on. One excellent inhabitant of this ng suggested it is coil freeze-up. Is there any way to fix this? If not, I will have to sell it or give it away and try to find a new car to replace it. But that is bad cause the
new S Klasse only has the humongous 550 cc gas eater available. And I fear the return of gas lines like the 70s in Ca. So I won't buy the new
5.5 L engine which means I will have to go to the Rexus LS430 Kudzu Kar. Suggestions to fix the AC problem? The professional wrenchs at Smilin Sams will fix it, of course, but the head guy didn't seem to have any ideas when I called him when it happened. " 96 S420
What is not clear here is whether this happened immeadiately following the evaporator repair or just surfaced now, 9 months later? Actually, it may not matter come to think of it. Because the evaporator may not have frozen up until recently because it was used in relatively warm weather.
I'm not familiar with your particular model, but in general, here's how many of them work. There is a valve at the evaporator connection that is controlled by a temp sensing capillary tube that goes into the area of the evaporator coils. When the evaporator is warm, the valve is open. When it drops close to freezing, the valve closes to stop the refrigerant flow before the evaporator can freeze. It's possible that when they did the work, they either did not put the capillary tube back into the evaporator properly so that it is not measuring the temp of the evaporator, but the cabin air, or damaged it. I would at least have a chat with the shop that did the work and see what they have to say.
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Check your freon level... it is probably low again... you might have a leak elsewhere instead of ol' evaporator. I know I know... piss ya off eh?
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1) it sounds like they neglected to install the evap temp sensor all the way into its position OR it has fallen out of the heater case. I doubt it is disconnected electrically, it may be bad though. You have to remove the lower dash panel on the left side. The evap temp sensor is above the gas pedal, in the left side of the heater case.
2) MBUSA announced yesterday that the new S600 V12 is going to be released in the US but no ETA. I know, that is the wrong direction you wanted them to go :)

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Thanks for the suggestions so far. The stopping cooling problem showed up right after the new evaporator was put in. So I think that does point toward the evaporator temp sensor thingy, drat! If they only have to remove the dash panel on the left side that may be pretty easy for them to do and I may even be able to get a big enough loan from the bank to get that done! Of course I assume they will not want to do that on their own cost. I just don't use the car for that many long trips, or at least haven't. Every time I did use it last year, it had that little cooling problem show up and I called them from the road. Now that I have a new knee and can walk around and kick various things trip frequency may change, of course.
mcbrue warmly under the bridge in the trailer down by the river
96 S420
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