Will it ruin the A/C system sooner if I leave it on all the time, when turning off and starting the car? I heard that it can ruin the compressor if it's left on and the engine is turned off. I just want to know if that's true. Because of that, I always turn the system off when turning the car off.

__________________
1992 Mercedes-Benz 400E
2002 Mercedes-Benz ML500

I don't think it makes a difference.

I can say though, that it is best to not set the wheel in the fully hot or fully cold position, and also to not set the fan blower speed to continuously on "high" or "low", but rather use the "Auto" button.

Drivers have the feeling that full heat or full A/C will get the passenger compartment to the correct temperature fastest.

This doesn't allow the system to work as designed.

To get the longest life from the automatic climate control system, allow the system to exercise all components.

If the temperature inside the car is more than 4 degrees away from the setting on the temperature wheel, the system will use full heat or full A/C regardless.

As the interior temperature approaches the setting at the climate control panel, the automatic functions will slowly reduce blower speed.

Allowing the system to work in its automatic mode, with all components functioning, will prolong the life of the system.

When flap controllers and valves (vacum operated) don't move for long periods, they tend to stick in position and ruin the component.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

Zero i LOVE your icon,, two words,, "CHARLIE MURPHYYYYYYYYY!"

__________________
2001 Mercedes-Benz C320 3.2
1991 Mercedes-Benz 300E 3.0

Believe it or not, the service manager at the local M.B. dealer has told me that if you switch to "EC" (turning off the compressor on the A/C but leaving ON the fan) three to four minutes before you turn-off the car at the end of the day -say your last drive going home-) it could save the life of your evaporator, or at least extended considerably.

This is very useful considering how problematic the evaps can be on W124s and W140s.

__________________
A. Rosich
CL 500, 1998
S 500 L, 1998
E 320 T, 1995 [Sadly sold ]

It is Sunday morning after a time change, so my telepathic skills are running a little weak this morning. What MODEL and YEAR are you driving?

We don't know if this is a climate control or a manual system. For example, with a 124 car, the climate control will automatically delay engaging the compressor to give the engine time to build oil pressure.

The compressor being engaged while starting the engine won't hurt the compressor, it will hurt the engine because of the added load while oil pressure is building up.

The compressor and clutch are designed to kick on and off while the engine is at speed so it doesn't hurt the compressor.

If you do have a 124 or newer car, just set the temperature where you want it, push the center button and FORGET about it. You can turn the temp dial a few degrees cooler or warmer after temp has stabilized, but let the thermostat do the work. By maxing or mining you will get to comfortable temperature no quicker. The system will get it to the set temp as quick as it can.

Good luck,

I think zeronero has a W124 400E.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

prior to starting any vehicle to make sure all a/c's are in the off position. so i applied this to my own vehicles and took it a step further and would do exactly as a.rosich said and turn off my a/c 5mins before to get the moisture out of the system.i never get the bad smell when i return and use my a/c.it's good to know that there is a side benefit in taking care of the evap.as an extension of this REGARDLESS of where you live,it would be a good idea to run some heat through the hvac system to keep everyhting 'lubricated'

__________________
'95 s500 (bought for wife but can't bear to share!!!) 125kms
'92 legend 180kms
'88 tbirdturbo(fantastic car-only regular maint.)120kms
'87 mustang gt(gone)
'86 tbirdturbo(gone)
'85 mustang gt(gone-but not forgotten)

I forgot, what can I say

suginami is right, a '92 400E

So the automatic climate control in the W124 automatically shuts off the compressor and other components before the engine shuts off and then at start up waits until the right time to engage, it's that advanced!???

So that means it pointless to turn the system off when turning off the car?

__________________
1992 Mercedes-Benz 400E
2002 Mercedes-Benz ML500

It does not know when you are going to shut off the engine, so it can't turn off the a/c ahead of time, but as long as the evaporator drain is not plugged there is no need to turn off the a/c before turning off the engine. By the same token whether the compressor is disengaged before the engine is shut off makes no difference as far as the system goes. The compressor will stop its work either way and the pressures will equalize through the expansion valve.

When starting the engine, the climate control will not allow the compressor to engage for a delay that allows oil pressure to build and stabilize.

The 124 Climate Control will last longer and be more effective if you just set the temperature that you like and forget about it, winter or summer. Leave the center button pressed and the auto fan button pressed.

Mine has been this way for 6 years and I have had to do nothing to the system whatsoever.

Good luck,

In my mind, an automatic climate control system, like those installed on W124, are automatic and does not require human intervention.
Except for the rare few time I switch my system to "defrost", it has been running on full "automatic' for 14 years and 390K without ever missing a beat. I still have the original R12 refrigerant in my system.
There is no reason to "play' with the temperature settings as it will not cool or heat faster, whatever its position.
Leave it alone.
jackD

For the 1994 E320 I've been in the habit of doing what Larry described above (using the auto button with the center button depressed) and letting it run all the time with one exception...

Before I shut off the engine, I hit the "0" button on the right side and actually turn off the system. When I restart later, after letting the engine warm up a minute or so, I hit the center button again. They system has worked perfectly for many, many years.

Am I reading correctly, that it's better to not bother using the "0" button to turn it off and just leave the center button pressed all the time?

__________________
Michael

1988 300 SL (5 Speed)
1994 E320 Wagon
1997 C230

Exactly.

More precisely, if the temperature inside the car is more than 4 degrees away from the setting on the temperature wheel, the system will use full heat or full A/C regardless.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

It appears that everyone here understands the basics of a thermostat so I don't think I will hurt anyones feelings if I say this here.

It never ceases to amaze me how many people just flat don't understand how a thermostat works. I'm not only talking about cars, I'm talking more about indoor thermostats. I've seen so many people go to a thermostat when uncomfortable and turn it as far as it will go. They just don't understand that this will not heat them or cool them any quicker.

I worked for a software company for many years that was founded and run by a very smart and hard working man. His education was electrical engineering as is mine. I remember many times being in our conference room and the temperature would be a little too hot or a little too cold and he would walk over and max the thermostat. For him it was particularly bad. You would think that someone educated in technicology, particularly electronics would understand a basic bimetallic strip and electrical switch.

Have a great day,

Larry: Myths are also frequent with professional mechanics.
last week, I was told by a mechanic with 30 years experience that I should not park my car so I have to back-up in the morning instead of first going forward. He said: Always park your car facing the street in your diveway.The transmission lubrication system does not allow for any oil circulation in the transmission in reverse gear. Oil will only circulate when the car is in a foward gear. Yyeeaahh.
JackD

I have yet to meet a woman that understands a thermostat. Most men don't either, but a few of them do. I find it most helpful to tell the offending party that I will beat them to a pulp if they touch the thermostat - that seems to work well for me, anyway.