mdreef

Wondering if anyone else has heard of the problem I'm having with my A/C in my 2010 E550. My A/C system works just fine most of the time, but the minute I rev the engine higher, let's say to downshift and pass someone, it quits cooling. The blower continues to work but the compressor shuts off until I manually turn off the system and then turn it back on a few times. I've had this problem for years, even after MB Dealer looked at it and serviced the system. The drive belt and pulleys are new so it's not because something is slipping.

Has anyone else encountered this issue?

Thanks in advance

kajtek1

Scan for codes

mdreef

Thanks for replying. I have a BlueDriver OBDII scanner that doesn't really do much - I mainly use it for CEL diagnostics on my old 911. What scanner do you recommend for deeper access into MB systems?

Thank you!

kajtek1

Right now Autel HT200 seems to be the best deal.
$49 at Walmart and free shipping.

Arrie

A/C compressor turning OFF during hard acceleration is something that should happen. This used to be called WOT (Wide Open Throttle) response to turn compressor OFF for the maximum engine power output to the wheels. A/C compressor can rob 10-15% of the engine power so for maximum acceleration the compressor turns OFF.

But I don't understand why you would need to turn the system OFF and ON again to get it cooling? Unless you just don't wait long enough for the system to return to normal operation mode.

Sunnyslope48

I wonder what's going on with your BlueDriver. Mine works just fine on my 2016 E350. Perhaps you have a much newer car?

mdreef

Actually my E550 is 2010. The blue driver is working just fine, but it's not showing any codes at all. I did a scan of all systems and all came back fine. Arrie's post about the WOT feature makes sense, but as he stated, one shouldn't have to manually turn off and on the system to get it working again. I don't think I'm low on refrigerant because my A/C system works very well in the Texas heat most of the time - only fails after wide open throttle.

I was hoping someone else might have experienced this and had a possible solution.

Thanks everyone!

kajtek1

I heard that computer cutting AC compressor off for better acceleration is AMG feature, but it could happen on lower end models as well I guess.
Still that would be few seconds, so you should not even notice difference in air temperature.
My car does ECO stops in 110F and I still have cold air coming from the vents for almost a minute, although at lower flow.
Now "I don't think I am low on refrigerant" phrase would be appropriate on religious not technical forum. Get the values read.

mdreef

You're right - I should have the refrigerant level checked just in case, but since MB Dealer did A/C service last year, I wonder if that would be the cause. My car has done this for as long as I have owned it (almost 6 years) and the system has always worked well except for the occasional wide open throttle. Wouldn't the compressor shut down completely if refrigerant is below threshold?

I will have MB look at it again and will report back.

Thank you!

kajtek1

For the price of single troubleshooting at stealer, you can buy about 3 scanners for DIY troubleshooting.
Modern AC system works with 7 sensors or more and has several programs for different occasions.
Guessing or crystal-balling is not having good efficiency.

Arrie

If your refrigerant pressure is too low the compressor will not run at all.

How long do you wait after the hard acceleration before you do the system OFF/ON cycle? The programming could be made to keep the compressor OFF for a few minutes after hard press on the pedal assuming you might be doing hard driving more than just one time.

Sunnyslope48

After the wide open acceleration, pump is turning like crazy, MAYBE the pressure is too high? Pretty sure there is a high pressure cut off on most vehicles.

mdreef

I used to think that my BLueDriver scanner was pretty good for the money ($99) but it looks like the Autel HT200 has many more features for $68. Thanks for the recommendation!