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Discussion Starter #1
The car had the EC light staying on. I checked the codes it had pressure sensor and low freon codes. I replaced the pressure sensor on the reciever dryer and charged the system. I reset the codes and the car drove for a few days everything fine. The EC light is acting so strange if I drive short trips everything is fine but if I take a trip of any distance over 30 miles or so. The EC light will come on. It has done this on my last two trips and when I check codes it has no codes stored, has anyone ever seen that. When this has happened I can reset the light and the compressor will come right back on and the freon level is correct. I have my actual values here to help if anyone can help determine my problem.

At 72 F on auto

In car temp 27 C
Outside temp 45 C
L heater core temp 2 C
R heater core temp 2 C
Engine coolant temp 96 C
Evaporator temp 1 C
Refridgerent pressure 13 bar
Refridgerent temp 58 C
In car temp 24 C
Outside temp 44 C
Sunsensor 4.1 v
Emissions sensor 2.8 v
Blower voltage 6.0 v
Circuit 58d 0%

I don't really know how to read into this so if someone would help me figure out if my readings are normal or if they see an issue that may be causing my problem to be happening. I have also added UV dye and looked the system over good for leaks and cant find any leaks. Thanks
 

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99 E430, 01 E430 Sport, 00 SL500
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3,266 Posts
>>Refridgerent pressure 13 bar

My cars read 15, gear in Park, max vent, LO temp, EC light off.
 

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2001 C320 W203 Black on Black. 1997 E320 W210 Silver (RIP). 1995 E320 W124 Pearl Black.
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595 Posts
Just wonder if you evacuated before recharge, if not that might be the cause and how much you charge might not be enough. There're info in the stickies you might need to read. The system need to evacuated and charge properly to the recommand amount.
 

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Discussion Starter #4
What I don't understand and want to see if anyone else does, is that I could let the car sit and idle all day long and the A/C would work great. I can run quick errands around town 5-10 miles from home and everything works fine. As soon as I get on the interstate and start to travel around 30 miles down the road is when the EC light suddenly comes on. I can pull over clear the codes and it is good until I try to take another trip, without doing one thing to it. I just can't understand why this is. The EC light came on Saturday night after I had been driving for approx 30 min. I pulled over checked the codes and the funny thing was it had no codes in it, it said E FF as soon as I went to pull codes. I cleared the light drove back home, everything fine and it has been fine ever since then, I let it run in the driveway today from 10 am til 3 pm without a hitch, A/C blowing very cold and no EC light. What could be causing this.
 

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2001 MB E320
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Just going to throw this out there... There might be some air pockets in the system. The longer you drive the more time it has to collect at a weak spot and cause the pressure to drop. I think you need to get it evac/charged properly. These a/c units are a little hyper sensitive.
 

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99 E430, 01 E430 Sport, 00 SL500
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The read 13-bar refrigerant pressure might be at border line. The system would respond intermittently to borderline condition since it's dynamic. As I recalled, 11-bar read at idle would definitely light up EC light.
I'd charge to 15-bar as instructed in the stickes to rule out one uncertainty the go from there.
 
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