[RebeccaNC]

Hi all,

My ML has recently started exhibiting an air conditioning issue. When I first start the car, it blows ambient air only even though the air conditioning should be kicking on. After driving the car for 10-15 minutes, the compressor seems to start and it begins to blow cold air. This continues while I run errands, stopping and starting the car again. Once it's back home and in the garage overnight again, the same thing happens.

It did this once three weeks ago, then was fine. Just started again two days ago, and both times I've driven it has happened. Outside temperature is between 80-90F, and I have the internal air conditioner temp set to 70 deg.

What could it be? A bad temp sensor? Low refrigerant? Please help!!

Thank you!!

-Rebecca

 

[43sqd]

If I am guessing correctly, it would seem to me that your A/C is operating correctly when you a driving above 30-40 MPH but does not operate correctly at low speeds.

If so, your eng. cooling fan is not operating at high speed while the A/C is on.

 

[RebeccaNC]

Speed doesn't make a difference. It's the first 10-15 minutes of running at any speed where it blows ambient air, and then the air conditioning kicks in after that. Runs fine for the rest of my errands, even after stopping and starting the car several times.

Thanks!

-Rebecca

 

[43sqd]

Please post you entire vin#, 17 characters.

 

[RebeccaNC]

My VIN is 4JGBB86E16A077981. Thanks!

 

[43sqd]

When the eng. is cold, remove the two screws (if need be) at the firewall to expose the A/C line, start the eng. and select A/C.

Wait 3 mins. and feel the two aluminum pipes (high and low side}. One should be hot and the other cold.

If both lines are warm, then the compressor is not working.

If one is cold and the other hot, and there is no A/C coming out of the vents, then there is an issue with the Blend Door. Post back with results.

 

[RebeccaNC]

Thank you! I took it in for service and it is leaking refrigerant. It was down 1/2 lb., so they filled it up and added dye to it. I have to bring it back in when I get back from a trip to have it checked out.

 

[takwong79]

Thank you! <img src="http://www.benzworld.org/forums/images/smilies/smile.gif" border="0" alt="" title="Smile" class="inlineimg" /> I took it in for service and it is leaking refrigerant. It was down 1/2 lb., so they filled it up and added dye to it. I have to bring it back in when I get back from a trip to have it checked out. <img src="http://www.benzworld.org/forums/images/smilies/smile.gif" border="0" alt="" title="Smile" class="inlineimg" />

I have the same issue. Mine is a 2009 ml350. Do you feel this “no ac at startup” happens only when outside is hot? Eg. 85+ degrees. When outside is 70ish, the cold air blows immediately without problem.

I had taken it to charge up coolant last year and the shop fill it in. But I do not think that is the issue for my car.

Interested to know what you have done or fix.

Thanks

 

[43sqd]

I have the same issue. Mine is a 2009 ml350. Do you feel this “no ac at startup” happens only when outside is hot? Eg. 85+ degrees. When outside is 70ish, the cold air blows immediately without problem.

I had taken it to charge up coolant last year and the shop fill it in. But I do not think that is the issue for my car.

Interested to know what you have done or fix.

Thanks

You have an altogether different issue.