Wicked A/C on W210

[majooo]

Hello everybody,
I’m seeking your advice on my wife’s 1998 E320 (V6) station wagon, 147,000 miles with an A/C trouble.
When I bought the car I knew there is an issue with the A/C. I’ve expected some work, but never this much…
I’ve searched and searched the forum, but I couldn’t find anybody with these symptoms.
PLS get ready for a long write –up. I’ll try to cover everything I’ve done so far.
Right after purchase an independent mechanic diagnosed a faulty expansion valve (200+ pressure on the head side).
I’ve replaced the expansion valve with 202 830 01 84 (the one on the car was 210 830 00 84). Q1: Is this a direct swap – do I need to adjust the amount of 134a or anything?
I’ve not changed anything else.
Vacuumed, charged with 1kg 134a.

I know it’s hard to compare the values due to ambient temperature and humidity, but they looked much better (70 F day = low 30 PSI; high 130 PSI), but in the car
the left side vent was blowing warmer than the right vent

I suspected the duovalve. Cleaned, no change. I splurged and got a new one, no change.

I’ve ran the diagnostic menu and value 7- was out of wack =99

The EC stuck lid, reset the trouble code for low charge.
EC stuck lid again. I’ve changed the P2 value by 16. No more trouble code.

I’ve ordered a new pressure switch 140 830 00 72.
Unfortunately, I was not aware that this switch is installed without a valve. After removing the switch most of 134a charge escaped (stupid me). I’ve added 2 oz (60 ccm) of oil that I got from dealer (BG FrigiQuiet) to make-up for the loss. Q2: Is this too much / enough (I was able to seal the system before it completely escaped, but majority of 134a was gone.)

AS OF NOW: The A/C works. The evap sensor (value 5) turns the compressor clutch off right at 32F and engages the clutch again at 37F. Both L&R (value 3&4) show the same cold temperature (much colder than ambient – 40’s). The pressure (value 7) seems to be responding adequately to the load (4-11) the temp of 134a (value 8) seems to be also responding to the load (climes from ambient to 120F or more on idle).
So everything is great, but only for several clutch cycles. Sometimes it works only 1min sometimes 10 min and THAN:
the value 5 starts to rise. The left side starts to get signifanctly warmer. The right side stays colder.
This sometimes gets to the point of no cold air at all, or sometimes comes back to working perfectly for another short period of time.

I’ve a suspicion of a blockage.
Where to start?
I’ve ordered new drier with a new updated hose from the drier to the condensator (210 830 46 15).
I’ve read the 134a temperature sensor located on the drier (114 721 20 73) had potential flaw due to corrosion done by condensation in system). I’ve ordered a new one also.

Before I open the system again:
Q3: Should I suspect a blockage in evaporator (only right side stays cold most of the time) and flush it?
I hate to remowe the wiper, etc…
Q4: Could the expansion valve be faulty (even new)?
Q5: Should I flush all the lines to get all the oil out and start from scratch when adding oil to the system?

The car came with a lot of history. Nobody seemed to do anything with the A/C, but I can’t say that with 100% guarantee.
The car doesn’t have any other codes (A/C or DTC).
PS: I’ve noticed no aux fan. I know they get actuated by: A) ECT, B) relatively high 134a pressure (around 14). I’ve temporarily discontented the switch at the drier and the fans started to spin. Q6: is there any easy test / what to observe?

I’ve also changed the cabin air filters.

I don’t want to open the system again, after I change the drier.
This car is going to send me to the nut house. And the complains from my wife…
Thank you for your patience reading my horror story.
Looking forward to hear any advice.
Thank you for support in this great forum!

Mark.

[RichardM98]

On the expansion valve, the A 210... is the new version and the A 202 the older one. But I doubt that is the problem. In early models of W210 EC light on could be faulty temp sensor (moisture and corrosion) or low refrigerant level. Design of sensor was changed to correct the problem but I don't know exactly when.

From what little I know, it sounds like blockage somewhere. Since you've got a new drier coming, might as well wait and see it that's it. If the A/C system has worked well for 147K without repair then I'd say a few issues isn't too bad.

Good luck.

[Matt L]

A restricted dryer will cause warm left-side vents.

Compare the pressure reading at sensor #7 with the reading on the high-side service port. If the dryer is restricted, it will show as a big difference.

Mine was plugged up so badly that the line leaving the dryer was cold.

[majooo]

Hello everyone,
I just wanted to bring this thread to a closure.
I’ve changed the filter/drier, changed the freon temperature sensor, flushed the condensator. (The filter/drier was very plugged – I could feel a big resistance when I tried to blow thru it.)
I’ve injected more oil, vacuumed and recharged the system.
Everything is working great!
No more complains from wife :-)
Thank you for all your input.
M#.

[Matt L]

My dryer was also quite plugged.

I would not recommend flushing a parallel-flow condenser, such as is used on the W210. Replace it instead.