GDawgC220

What do you leave your HVAC on, "Auto" or "EC"?

DougandhisC280

Auto

GDawgC220

when i leave it on auto, the power on the I4 suffers a little, well, cuz it's an I4, lol. But i'm getting use to it now...will this strain out the A/C compressor at all over time?

blackmercedes

Contrary to popular belief, running the AC compressor is the best thing you can do for it. It requires the coolant (R12 or R134A) for lubrication, as it contains the oil.

The newer systems actually do not cycle the compressor on and off, but use a variable pressure compressor in order to keep it running all the time.

Commercial AC systems are moving toward the same style of compressor in order to have the system run all the time and lengthen the compressor life.

Using the EC button may actually shorten the life of your AC system.

vas2vas

AUTO......then again I have 6cyl it does put a load on the engine though, and pushes the needle up, especially in stop and go traffic.....

davis449

The A/C does put a load on the I6 too. I notice a considerable power difference when I have it on, especially in the heat and when there's elevated engine temperature. I usually have it on Auto and the fan on 1, 2, or higher in the summer. I do the same in the winter except the temp on the climate control is considerably higher.

fast mayte

yea i got a 4 and it really really sux with the a/c on. lately the engine's going over 100. proly 110. it used to be around 90. kinda getting worried about the headgasket. ahh well. one thing i really hate on a hot day is when the air fades in and out on hte center vents while acceleration. anyway to disable this?

GDawgC220

i think the way MB HVAC systems are designed is when you are accelerating, it takes power away from the A/C compressor and directs power to the engine so that you have the most power to move the car. Once you don't need that power anymore, it will let the compressor do it's thing and get the air into the cabin again. Kinda cool i guess...so u get power to accelerate instead of slowly moving forward, ya know?

About that 100-110...i've never seen mine that high. Most is 100 and that was on a 100 degree day sitting in traffic. Usually, it's around 90 at most when stop and go on like a 80-90 degree day...maybe u should have that checked out?

GDawgC220

i think the way MB HVAC systems are designed is when you are accelerating, it takes power away from the A/C compressor and directs power to the engine so that you have the most power to move the car. Once you don't need that power anymore, it will let the compressor do it's thing and get the air into the cabin again. Kinda cool i guess...so u get power to accelerate instead of slowly moving forward, ya know?

About that 100-110...i've never seen mine that high. Most is 100 and that was on a 100 degree day sitting in traffic. Usually, it's around 90 at most when stop and go on like a 80-90 degree day...maybe u should have that checked out?

Brandon24C

Running EC all the time can in no way damage the AC life. If you are worried about fluids moving, run the AC once a week for a little while just to keep it in motion. By shutting off the compressor and just keeping a vent, you put less work on the engine and save the AC. Less work should equal less ware. In any case, running the AC once a week or so is a great way to help it.

blackmercedes

It's a common misnomer that does not apply to Air Conditioning systems. Inactivity can shorten the compressor's life, and this is a well known fact among AC technicians. It's the truth for many items on your car, including your engine. I have seen many low mileage engines that need rebuilds after long periods of inactivity thanks to corrosion.

Also, the additional load on your engine of the variable system when operating at a low cooling capacity is minimal. When your car needs little AC operation, the variable pressure compressor operates at just enough capacity to keep the evaporator at optimum temperature.

Also, if you're worried about wearing out the bottom end of your engine on your W202, you're getting your priority list all wrong. There are many things that are going to wear out or break before it will. The additional stress the AC system places on the engine will never matter in the life of the car. Change the oil and filter frequently, and that will be fine for hundreds of thousands of miles. On a typical Mercedes, it's the sub-systems that will cost you big dollars in repairs over the long haul. The AC system, electrical accessories, automatic transmission, suspension components, and so on, will all break several times before the engine needs attention.

For those with ACC equipped systems, set and forget the temperature and let the system work as designed, and you'll have the longest life from your system. Also, change the cabin dust filter often. Not sure about pre-FSS systems, but on FSS equipped cars, the interval is every time the FSS counter "zeros." On most cars that's about once every 10,000 miles. That will extend the life of your blower motor and evaporator.