MbNeedshelp

I have 2001 S500 with no cold air, in South FL. I have checked out system and found everything works but no cold air!? MB shop with the "STAR" program checked out my car and told me everything is working, but still no cold air ?
I am going to change out the expansion valve. Does anyone have a good DIY link I can use. Thanks for any help.

ItalianJoe1

How are the pressures with the a/c on? Is the compressor engaging?

I believe the expansion valve requires removing the dash, not sure though on a 220.

MbNeedshelp

The Low side is very high and low line is very hot. The compressor does engage and the self diagnosis is giving me a code indicating high press switch. After running the A/C a while the "EC" light comes on and I can not turn it off, until I reset the unit and clear the code.

ItalianJoe1

What is very high? How hot is very hot?

A/C diag is all temperatures and pressures.

If you are seeing between 80-100 psi on both then i'd wager your compressor is out. How high is the high side when the code sets? What is the exact code?

wallyp

"The compressor does engage..."

The W220 has no clutch on the compressor - it is always "engaged", unless the rubber cushions in the drive pulley are sheared. Sheared cushions usually mean that the compressor is seizing.

Use a good light and see if the very small bolt in the center of the AC drive pulley is turning with the rest of the pulley. If not, the cushions have sheared, and the compressor may be (probably is) seized.

MbNeedshelp

Yes I'm aware the MB compressors work very different . The small center bolt is spinning and building pressure till the system shuts itself off, which is indicated by the red light inside "EC" button on the control panel. I's been checked out and the system "electrically" is working, so I was told there is a blockage prob in the expansion valve. I was hoping someone has replaced that unit and could give me a heads up of any tips or surprises to watch out for. I have an idea how to change the valve. The dryer will also be changed and have a vacuum pump gauges and Freon ready to complete the job. I'm doing it the job this weekend either way and was praying for some extra knowledge to have success . Thank you guys for all your help thus far.

wallyp

Wish I could help, but fortunately haven't had that problem yet...

ZephTheChef

Let me preface this by saying I'm not very familiar with the Benz A/C yet, but very familiar with automotive A/C in general. If you've got high low side and high high side pressures, your system is probably either overcharged or the condenser isn't cooling well enough. Is your fan working properly? Have you tried trickling water on the condenser to see if it affects the pressures or makes it start cooling? What are the actual pressures when operating? Just telling me it's "high" doesn't really help as everyone may have a different understanding of what high is.

Kristol Quigley

did your replacements fix the ac issue? Did you replace the expansion valve? Im getting ready to do the same repairs, my ac is hot on high and low, clutch emgages when given 12v but not cooling and a drip of freon sends the pressure guage into hot zone. Any info you found can be helpful.