mekantor

Hi - I'm trying to troubleshoot the AC system. I'm hoping its an issue with the expansion valve.

But in case its the compressor, have any of you had it fail, and if so did it present with errors in Xentry?

I have no errors, just near-equal pressure on low and high sides. Xentry reports the compressor is running and drawing current from the control valve.

And apparently there is a lot of variation in AC systems over the model years of the GL/GLS. Mine has R134a with rear AC, also making it have the most-expensive compressor to replace.

kajtek1

What is the pressure?
Takes only seconds to troubleshoot the system when you have adequate scanner.
Start with sensor calibration test.
Read all AC sensors on cold morning, before engine start. All temp sensors should show the same with about 2 degree errors.

juanmor40

A failed clutch, or electronic control valve will prevent the compressor to work, it will not raise the pressure.

Is it a bad compressor? Or failed signal to activate either? -> diagnose control signal

​​​​

arsupisemnet

Once again. There is a variable performance valve on the side of the compressor which is failed. Drain system, take valve out, replace it with one from Amazon, and keep driving.

mekantor

Thanks for the replies. I was expecting a failed value to give errors in Xentry, but apparently it may or may not. Xentry shows no errors, no shutoff signals, and allows me to actuate the ECV at various load levels.

I replaced the expansion valve, vacuumed, and filled to spec. Low and High still equalize, temperature sensors are all showing ambiant.

I think I'll replace the entire compressor, and the dryer while I'm at it.
I could do just the ECV, but at this age and mileage its probably better to swap the entire thing. On my E55 I've had the pulley just fall apart after enough wear.

I'll post an update once I get the replacement and put it in. A few days ago I got a used Robinair machine from a shop, makes all this work much easier and faster.

juanmor40

What values if refrigerant pressure did you see when the valve was actuated? 8 bar? 13 bar?

Were you able to actuate the clutch? Hear the click?
the AC compressor for recent MB have electric clutch unlike the onesvin the E55 W211 of the past

mekantor

This is an early-model GL which doesn't seem to have an electric clutch as far as I can tell. I think its always-on and the valve actuates the internals to adjust compressor load (like W211). Open to being wrong and will confirm.
When shopping for a compressor, I saw there are specific codes regarding year of manufacture, and apparently some even came with a 1234yf system.

It started around 7 or 8 bar and steadily rose to ~9 as the engine heated everything up. There was no movement when actuation was happening.

roadtalontsi

In xentry aac module there should be a tab under actual values for reasons for refrigerant compressor shut off. If there aren't any it's probably the compressor. All US spec 166's are r134a. y1234 came in a couple of 231's then shortly afterwards the only factory that made it had problems. It was like $600/lb or something insane. MB also didn't like that it was flammable. There was a recall to remove y1234 and convert to r134a again. I think they just now started using it in newer benzs again.

mekantor

Yep I saw that tab, all the shutoff reasons were set to NO. Xentry thought everything was perfect, and it was drawing current which I assume is the valve. I could set it to 50% load and see the current change. But no change in pressures or output temps.

juanmor40

Got it. If the compressor cannot reach at least 13 bar, it would not cool.

Now the question, is it the ECV not working correctly on demand, or the compressor worn? Need to think about it

Before buying the compressor, check yours. The ECV may have yellow dot, or triangle at the top. If so, there is a diode. Be certain the new one matches

Mind sharing exact model of your vehicle?

If your compressor looks like this


It has an electric clutch. That is the model listed for the X166 Bluetec. Is that your model?

mekantor

Oh yeah I've been all over diode hell with the E55. All the catalogs listed the wrong one so I just had to buy n ECV separely and assemble the proper compressor.

I'll get a closer look at the one on the car tomorrow. The VIN is 4JGDF7DE9DA232333, which resolved to A0032309811 in EPC.

juanmor40

Interestingly, that compressor does not show up in the Denso catalog, but definitely a Denso. Saw one in eBay, the same code A0032309811 and the picture shows the yellow dot (diode), and found the ECV is sold in Europe ( https://www.autodoc.co.uk/acauto/18580941). I am sure you can find it locally if needed (either RTX Tech, BMW/VW or similar brand)

I also noticed it is the "clutchless" type, or permanently engaged.

arsupisemnet

there are plenty Mercedes ECV with a diode on eBay or Amazon.

juanmor40

Correct,, but there are few variants besides the use of the diode.. The link points to the exact ECV for that compressor: diode, specific length, and no mesh/filter. With that information it is easier to filter from other providers

mekantor

I have a few spare valves and decided to try replacing it on the car while I'm still waiting for the compressor in the mail.

Wow this one looks terrible. Did it run out of oil and just grind itself down? Definitely replacing the entire compressor now, and may need to flush the system to get rid of debris before the new one is destroyed.

juanmor40

Wow.. Very interesting. Never seen one that bad. Thank you for sharing.

It would have failed a lot earlier w/o the mesh/filter.

mekantor

The expansion valve had some dark coloration in it, I didn't think much of it, but I suppose it makes sense now that's its more fine metal debris.

mekantor

Ordered a new condenser as well