ML320 Doesnt Blow Cold a/c - PeachParts Mercedes-Benz Forum

sdanville · #1 06-03-2007, 09:31 PM

Know this, I did spend a couple hours in the forums and testing before I posted.

No cold air. So I recharged and believe I had good pressure. Its in the blue on the guage.

Then reading here I checked and did indeed have a blown fuse for the air conditioner fans. But when I turn on the air nothing happens.

There is no decrease in RPM, the vents have warm air blowing thru. The fans by the radiator do not turn. No condensation dripping underneath , no cold lines under the hood. I dont have the high pressure gauge nor understand it.

Any suggestions welcome. Wait..not any suggestions welcome (like take it to the dealer ya loser) .

steve

mbdoc · #2 06-04-2007, 08:22 AM

What year ML?

Does the a/c compressor come ON & does the a/c suction line get COLD?

The ML heating & cooling system does NOT have a heater valve..IF the a/c suction line gets cold but still no cooling possibly the blend air door isn't moving.

sdanville · #3 06-04-2007, 08:46 AM

Its a 1999.

As far as I can tell when I turn on the air the compressor does not turn on.

There is no change in RPM like one hears normally when the compressor turns on and taxes the engine. I cannot feel any cool lines under the hood either.

Thanks for the reply.

mbdoc · #4 06-04-2007, 09:12 AM

IF the pressure switch on the high pressure line is sending the correct signal??

AND the a/c controller is telling the AAM to turn the compressor ON...then either there is a wiring problem at the bottom of the fuse box (very common problem) OR the AAM isn't sending that signal..

AAM=all activity module....can be diagnosed with scanner to see if A/C signals are present(live data).

sdanville · #5 06-04-2007, 09:23 AM

I think we just passed my limits in terms of testing and understanding.
I read the wiring harness is a recall , maybe it wont cost me a service call.

mbdoc · #6 06-04-2007, 09:59 AM

The only A/C related harness on the ML is the aux fan wiring..not a recall but an up-date.

sdanville · #7 06-04-2007, 10:08 AM

Ive read about a bad connection under the fuse box for the A/C.

But have not read step by step instructions. It looks to me like about 5 screws to pull the fuse box up... this weak/bad connection...once found,,then what .?

UPDATE I pulled the fuse box open, checked what I believe to be to correct connection. the connection looked flawless,

time for a new direction. Here is how I have been doing. Last week not only did my air go out..but my keys went through the washing machine. I dried them for a day but no luck. Shot. So I stopped locking my door,,it only took 3 nights and my ML320 was cleaned out. cash, perscription drugs, my complete owners manual package including radio code card. so tonight when i messed with the fuses - I disconnected the battery and lost use of my radio.
UPDATE FIXED:6-5-7 After reading I learned how simple it is to see it the compressor was kicking on. Just look at the end and see if it turns. It did. then a minute later it didnt. recalling lack of R stuff can cause this I added a can and have cold air. So using my gauge that was in the blue zone isnt enough for my truck. This may be the beginning of a good luck run. Happy Trails ya'll.

steve