lexrex

Several weeks ago I took my E320 to a shop to have an A/C problem fixed. They wanted over $600 just to diagnose it, and I said no thanks. They said I had a flap problem. At the time, the A/C was blowing cold air only out the right side. The left side blew ambient air. It wasn't warm enough outside to tell if the right side cold air was as cold as it should have been, but it was noticeably cooler than the left side.

I had a bad evaporator temp sensor which I had replaced. But that didn't fix the problem.

The temp today is in the mid 80s. Now, neither side blows cold air. I ran the flap test and found that #2 (right diverter flap) would not activate. Ironically, it was the right side that was blowing cold air before.

Here's the info from the self-diagnosis of the A/C with the engine off & cold:

01 - 118 F
02 - 85 F (within 1* of dash)
03 - 103 F
04 - 102 F
05 - 103 F
06 - 139
07 - 5 bar
08 - 89 F

I let it warm up and drove a couple minutes. The refrigerant pressure reached a high of 8 bar but settled around 6 bar. None of the heater core / evaporator core temps changed significantly. What should the refrigerant pressure be? 6-8 bar strikes me as being very low, especially considering that it sits at 5 bar when the engine is off. I could have sworn I saw it as high as 13 bar a month ago. Hopefully I don't have an evaporator leak!

For what it's worth, I hear a hissing noise from the center vent area when the A/C compressor is turned on. Perhaps a vacuum leak for actuating the right diverter flap that failed?

Any thoughts would be greatly appreciated!

Blake

silver00E320

I'm not much help with information on the readings you have but I had (maybe still have) an air conditioning problem that was like the one you described. From my experience, you would be better off asking a Wal-Mart Door Greeter what they thought about it instead of asking the dealer for an opinion. If they actually do the diagnostics - then that's different.

I had the same problem of the left vent getting warmer than the right one. I called and talked to the service department at my local dealer and was also told it "could be" the flap that vents the air to the left side. A week or so later the right vent started also getting warm and I realized it was probably something more serious.

I took it in for them to look at it and only had to pay $150 for them to tell me it was leak in the evaporator that would cost $3500 to correct. Needless to say, I left without the work being done.

After posting a couple messages on here asking if anyone knew of a good (and I emphasize honest) shop in Central Florida and getting no response, I ran across a link on here that talked about an air conditioning sealant you could put in the system much like the radiator stop-leak.

I called the local Goodyear shop (which is only a mile from my home) and found they did not carry the brand sealant I was looking for but had one similar to it. I paid them $200 for a diagnostics inspection, a full charge of R-134A coolant, the sealant and a florescent dye additive which I asked them to put in just in case the sealant didn’t stop the leak and I would have to have it looked at again.

That was over three weeks ago and so far I haven’t noticed any difference in the air temperatures between the left and right vents. The previous charge lasted only about two weeks. If this holds long enough then I would like to trade the car or, better yet, sell it to the dealer and stick him with the repair.

I need to do the diagnostic test that you did. I found the instructions for doing it but the figures for the readings are a little different than what I need. Do you know where I can find out what the readings should be for a 2000 E320?

JimE430

For what it is worth......The flaps are air operated, and you might be able to trace the lines to a leak. One side will always be a little different from the other, as the cold air enters from that side. The noise in the middle is a bad valve. Shortly after I bought my car I noticed my car had the same noise. My car was still under warrenty and the valve was replaced. The part is an Expansion valve, #202-830-01-84 and is a common problem. This could affect your AC operation.
Jim

dshinn28

In order to help you diagnose and target on to the problem, you should pull the error codes from your digital climate control panel. This will help you focus onto the exact problem. This is the beauty of the digital display unit. The codes you pulled are merely the info codes. They provide information but not enough. I would suggest you read
http://www.continentalimports.com/ser_ic40142.html

This article is specific to your car, so you are in luck! If you need the meaning of certain error codes, I'll try to help. Good luck~!

lexrex

Thanks everyone for the advice. I took the car to another shop and told them to just recharge the A/C. It was about a pound low on R134a. The recharge cured the problem completely...both vents were down to about 35 F. They put dye in the system too, and I need to check if it's leaking anywhere. If I indeed have an evaporator leak, it's seems to be slow enough that it's not worth replacing.

I had codes for evap temp sensor, engine coolant sensor, sun sensor, and emissions sensor. I replaced all but the emissions sensor.

Will look into the expansion valve re the hissing. The hissing is almost completely gone now that the system's fully charged.

silver00E320

It seems logical that a recharge would help - at least for a while. You mentioned you thought you had 13 bar on your refrigerant pressure reading a month before you saw it at 8 or 6 bar. A slow leak over years might be understandable, however that sounds like something more severe. If you did see a 13 a month ago then could there be an explanation as to why it dropped, other than a leak?

lexrex

I think the pressure is determined in large part by the ambient temperature. I'm not positive I saw it at 13... Certainly it's blowing colder now than ever, and it's a little under 10. It's not very warm out though (colder than when I might have seen 13).

hangup

lexrex, is it still running OK? how many bars are you getting now?
do you know how many bars these things supposed to have when new? i know it depends on the temp, but maybe there is a formula or a table or something.
i think i need to refill mine.

lexrex

Hangup,

I ended up having to replace my A/C compressor. It was leaking terribly. The evaporator seems to be fine.

The pressure really depends on the A/C load. On a 70 degree day, I've seen it at 6-8 bar. As the outside temperature temp goes up, the pressure goes up too. Yesterday it was about 90 degrees and running about 15-20 bar.

There's really no direct way to measure the refrigerant quantity without completely evacuating the system. Indirectly you can tell by observing the evaporator temperature and listen for hissing. Let the car idle with the A/C on for about 20 minutes. On a full charge (and a good compressor), the evaporator temp should get down to the 30s or lower 40s. If you're low on freon, you'll hear hissing from the expansion valve behind the center vents (sounds similar to spraying an aerosol can).

If the refrigerant charge is only slightly low, you'll hear intermittent hissing and the left & right heater core temps (diag. no. 3 & 4) will be different by about 10 degrees when both sides are set to the same temp. Right will be colder than left.

hangup

sorry to hear about your compressor must have been big bucks . . .

thanks for the info! i ended up charing it up myself today.
i'll look at the evaporator temp too.
so far i just used the method of obverving the temp and pressure at the high side and pressure at the low side while filling up from the low side.
it seems to have worked for now. blowing pretty cold. maybe not ice cold, but i think it is as good as it has ever been on this car (i had it for a little over 2yrs now).
i probably put around 700g in there.
if anybody wants to read more details on the process i used please do a search it's mostly typed up.
no warranty though, keep in mind i'm not a mechanic and this is the first time i did it. so it's mosly for the purpose of ridiculing myself

hangup

well, i don't have left&right, i think it's all one zone in my model (C43).
if i set the fan to low i can hear the hissing sound. that makes me believe that i still don't have enough in there.
i also looked at the evaporator temp. if the blower is set to high it's 75F!
on a low fan setting it only goes down to about 65F.
not 30s or 40s like you pointed out. that was 30-40F right, not C?
so i guess i need to add more until there is no more hissing sound in the dash and the evaporator temp goes down to normal levels.
i visually inspected the compressor and from what i can see and smell i don't think it's leaking in a big way, but who knows . . .
tubing doesn't look all that bad either.
i'd like to get a can of refrigerant with the die mixed in there. anybody knows where i can do that? i found something online, but it contained a sealer and i don't want that, at least not yet