rickjs

Its been pretty warm in the Bay Area lately, and when I first start my 05 E500 wagon, the fan blows up a storm, but the AC fails to start cooling until I've driven 2 or 3 blocks (15 to 20 seconds). Seems to mostly happen at the first start of the day, or after the car has sat for 6 + hours..

The dealer is telling me its "up to spec" and "this is normal".. but I've had this car 2 summers now, and would swear this only started in the last month or so... as now passengers will start asking if i can turn on the AC... I'm pretty **** about the car, and told the dealer i would have caught this long before and checked it out.. but they refuse to budge on taking it further..

thoughts on this?

Thanks
Rick

Barry45RPM

I accept the same thing on my car as normal. The reason being, that the car interior has been superheated by the sun, including all of the ductwork within the car. The A/C must first cool down the ductwork before the cool used to do that will reach the cabin. Until thats done all of the cold air that is being produced is being warmed back up by the black, hot ductwork. Its a perfect excuse to lower all the windows & open the sun roof with the key before you get in to partially dissipate the heat within the cabin.

These R134a cars do NOT produce as much cold as the old R12 cars did, and thats a fact. Your wagon has more interior volume to cool down also, even though my sedan has the same A/C system.

I drive for about a minute before I think about closing everything back up. These really hot days are when you tend to notice it.

Vik888

I swear I read about a "fix" for this issue that I read about on this forum for the delayed cooling.

I don't buy the ductwork explaination. I had my nearly 13yr old 4Runner in Las Vegas 2 weeks ago (108F outside), it must have easily been 140F inside the hot car parked for 2 hours. Got in, turned on the AC, and it blew cold air in less than 15 seconds.

Diesel Benz

You seemed to ignore Barry's comment on freon versus R134a, not fair to compare the two cars.

And certainly hot ducts and heat exchangers and all that do have an effect, difficult to say how much though.

It could be an issue if there is a significant difference to the earlier experience, if the conditions are comparable.

Vik888

Ah Ok. I had no idea what R134a or R12 was .. figured it had something to do with MB model #'s. My mistake.

rickjs

thanks all.. yes, this seem to be changed from when i first got the wagon about 1.5 yrs ago.. I can understand a short delay while ducts, etc... start to cool.. but after 15 sec.. there is absolutly no change to the temp, then suddenly, cold starts.. and many times during the day, the chilled air starts within a sec or two.. I just moved very close to Oakland MB.. i may go visit them to see what they say...

emilner

No a/c system can blow cold air instantly. Upon starting the car an a/c system has to first pressurize the freon then get the coils cold enough to actually cool the air being blown past them. Once the air is actually cooled, it then has to cool the ducts and air in the ducts. Don't forget it takes quite a few passes for the air to lower to your set tempurature. In the beginning every bit of air being drawn into the system is very hot, the system does not instantly turn that air to your present tempurature. I find it takes 30-60 seconds to begin to feel cooler air coming out of the ducts. I have never seen another motor vehicle do it faster.

With that being said I do find the MB system to be under powered and quite noisy. I also find it struggles to keep a comfortable tempurature, it seems the center ducts are to low in volume and the outer ones to powerful. If you try to adjust them it only increases the noise even further. I am also surprised the recirculate button does not turn on intially to cool a hot cabin. Every car I have been in will run the recirculate button until the cabin reaches the preset temperature.

rickjs

yes.. good point, i guess the same principal as the heater.. wont come on until heater core is warm enough... on the recirculate button.. i notice when the AC does first come on with a hot day, the "max cool" notice is on in the temp display area.. i was wondering if that was turning on the recuirculate without the button having the led on? .. the air flow does change slightly when i see the "max cool" go off..

KYBENZ

Is the air not cooling or is the blower not turning on?
There is a service bulletin for these cars concerning intermittent blower operation. The blower regulator is replaced and on some the motor and regulator. The bulletin # is DTB - P-B-83.25/76b .
This is what happened on my 211, it would power on for a second and then shut down for a few minutes before returning to normal.
I see that you stated that the motor does blow. I will still leave this post up though in case others are having my problem.

rickjs

I actually had that issues last year, and that was done.. this summer, it blows like a windstorm at max, just no detectable chill for about 20 or so seconds.. which turns out to be a long time when its 90 and sunny out :-)

csumt76

I've had an 06 and 07 E now... and they always take a bit to blow "cold" air on hot/sunny days. If you know how the system works, it shouldn't be that hard to understand. The logic of the control module even factors in the air not being cold immediately. When max cool is selected, the blower does not instantly shoot to %100 to pelt you with hot air. The footwell flaps are even slightly open to help circulate air through the heater case, then the blower speed is gradually increased.

Barry45RPM

I agree. I had a loaner Camry a couple of weeks ago and the cold air blowing out of their center vents past my arm on the steering wheel, was stinging cold. The MB system is probably just sufficient. I noticed that the "cooling program logic" the system uses is different that my '04 also, as it seldom goes into "max cool"/screaming outside fan noise mode, and it defaults to slower inside fan speeds too. Also in moderate to cool temperatures, it blends heat in at different temps than the '04 did. While I drove around all year with the '04 set at 73, I use a variety of different settings now based on the current outside temperature. The system seems to blen in some heat when it is not necessary or desired.

I agree also that the car should go to recirculate mode on startup to assist in a more rapid cooldown.

toubia320

Personally I experienced the same thing after letting the car sit out in the sun for more than a day. However, ever since i kept it in the garage I have not experienced this problem again.

rickjs

Toubia.. i think you got it... last year I lived in a much warmer area, but the car was garaged.. this year, it sits in the driveway.. probably why i didnt notice the issues last year, and it seems new to me now..