A/C intermintent 2nd time @ dealership. Help needed!

[firedawgs]

2009 35D w/ 10K miles.
Added OEM trailer hitch/electrical/software 4 months ago. Dealer installed.

I notice when it is hot and I take a trip (30 mins+), many times the air won't blow cold air. The iDrive is set to blue (cold). The blower is working fine. The first time it happened, I could pull over, turn off the car, pull out key, open door, then reverse cycle to turn on the car, just to have the A/C blow cold for maybe 5 minutes.

I have brought the car into the dealer the first time, just for them to tell me the iDrive was set to hot. I, at that time, believed them, and went on my merry way. I then drove the other day to my sister's house which is an 1.25 hours away. It was 85 degrees out, and wouldn't you know the A/C stopped blowing cold air about 20 minutes into the drive. Turning the car off and on didn't work this time.

I called the dealer right up, frustrated as all hell. I questioned if in the shop last time, did they pressure test the system, check for error codes, etc. Of course, they said yes. But, the fact of the matter is that the A/C blows no cold at warm temperatures and traveling.

I figure this is going to be a hard problem to determine, so I wanted to see if anyone had incite on this problem. I did read one post on someone having no A/C during towing, and I have added the trailer hitch (OEM) through the dealer install, but have not used the hitch yet. I have a appointment next Friday, so any information I can give them would be great.

Thanks for the help,
Sean

[ard]

First, I am not questioning if YOU have an issue.

AC is hard to diagnose. As you know it is basically a cooling system that is controlled by an envirnmental control system. They can test the AC and say 'works fine', yet something may be up with the control system.

"Blowing Cold" is a phrase that drive me nuts. It is simply too imprecise- sellers use it to describe a good AC unit on a car for sale (who cares if it is 'blowing cold', the test is 'can it keep the car at the right temp'?) ...in your case maybe the target temp has been reached and the control system has (correctly) altered the temp so it no longer 'blows cold'.

you MUST have a very crisp and precise description of what it is doing wrong. For example, "Outside temp is 95, start car, temp is 95+ inside, AC is cold, interior temp set on 70, manually using dash vents, cold air comes out- after 20 minutes inetrior never reaches 70, air gets warm".

Also, you may insist that the diagnitic steps be spelled out on the work order. I suspect last time it was "C/S [customer states] AC not working properly. Check and Advise.".... the SA is 'stuck' with whatever the tech decided to do. THis time spell out the issue, AND negotiate with the SA what exactly the will do to test. for example 'test AC system pressures, and run for extended period monitoring temperature outputs"...etc.etc.

GL

A

[SCardamon]

Mine is in the shop right now for that issue. Out of nowhere the vents will simply shut off for me.

It is an issue of no air pressure or volume of air from the vents? Is air coming out that is not cold? Mine is an issue of air being cut off.

[firedawgs]

My issue is that the blower works all the time. The problem exist when I am usually at highway speeds and the vent no longer blows cold.

To be more specific to Ard. The car will start and run fine with cool air; either manual or automatic. I notice when driving on the highway; usually on a trip that ranges more than 20 minutes, I notice it start getting more humid and hotter in the vehicle. I place my hand over the vent and it is not blowing cold. I have tried to change the temperature setting to manual and 60 degrees with AC snowflake on, and still do not feel cool air. The outside temperature has been anywhere from 75-90 degrees. I have yet to see this problem happen during small drives around town.

The dealership had the vehicle for 2 days now. They ran the regular ECU diagnostics, pressure test, ran die in the system, and found nothing. Of course, they only drove it about 5 miles, but let it run for a long while. I did explain to them more specifically when I find the problem.

Now, I am going to pick up my vehicle without being fixed. The only option I feel I have now, is hopefully the problem will occur while driving the vehicle. Then hopefully I can turn around and head right to the dealership; which is totally the opposite direction for me. Also, hoping the dealership is open then too.

[jeremym]

I just noticed a similar issue in my 07 4.8. The DRIVER side vents blow cold, crispy, hand numbing air set to 65 or below on auto-soft/medium/intensive. The passenger side blows "cool" air but not the cold crispy stuff.

Climate control in iDrive is set identically. Rear climate is turned off (just to make sure I was getting 100% to the front vents) and both temperatures are set the same. The air pressure is the same, or very similar. Just the temp of the air is not exactly the same.

You know, that cold and crisp numbing feeling you get when you put your fingers in front of a vent with A/C on full blast? Yeah, that keeps me cold on the driver's side but the passenger side just gets "cool" and not "cold."

Let us know what fixes this. I'm very curious. I have an appointment for other issues in a couple of weeks so maybe I'll toss this in the service request.