How to diagnose a cold interior (in winter)
02-26-2016, 04:45 PM
#1
Senior Member
Thread Starter
How to diagnose a cold interior (in winter)
My W221 ever since I bought it 2 years ago has been colder than average in winter.
We keep our house at 70 deg F, and our other MB (a GL320) has the temp dials set at 72.
My side (drivers) of the S550 is set at 75 deg F, and my wife's side is 80 deg F. And she's still cold.
I'd say (to me) her side feels around 70 degrees, and mine is lower.
This has been going on every winter ever since I've owned the car. Car was checked over when I bought it by a really good MB tech and deemed in perfect condition (of course this issue wasn't apparent so he didn't specifically look into it)
Coolant was flushed last fall (no change), new thermostat since it was popping up with some codes every few months, and I replaced the blower motor about a year and a half ago. No changes from any of the above.
Yesterday a weird thing happened. Maybe it's just me, but there was an ice storm and there was a thin sheet of ice on the car when I came out after work. Car had been parked outdoors just as it is every other day, but thin sheet of ice on everything.
Heat seemed normal. Blower kept going till 1/2 way home which is a lot longer than it usually stays on high speed.
Is there some kind of temperature sensor I can look into? I have MB DAS/Xentry and am thinking I should see what interior temp it is reporting and compare that to a thermostat I place on the center console of the car.. just to see if there is a different.
I assume the system is getting its readings from the coolant system (to tell coolant temp), evaporator, and some kind of "interior" ambient sensor combined with a sunload sensor (to adjust heat/cool when the sun is beating down)
Do these interior sensors get gummed up and need cleaning? Do they fail?
We keep our house at 70 deg F, and our other MB (a GL320) has the temp dials set at 72.
My side (drivers) of the S550 is set at 75 deg F, and my wife's side is 80 deg F. And she's still cold.
I'd say (to me) her side feels around 70 degrees, and mine is lower.
This has been going on every winter ever since I've owned the car. Car was checked over when I bought it by a really good MB tech and deemed in perfect condition (of course this issue wasn't apparent so he didn't specifically look into it)
Coolant was flushed last fall (no change), new thermostat since it was popping up with some codes every few months, and I replaced the blower motor about a year and a half ago. No changes from any of the above.
Yesterday a weird thing happened. Maybe it's just me, but there was an ice storm and there was a thin sheet of ice on the car when I came out after work. Car had been parked outdoors just as it is every other day, but thin sheet of ice on everything.
Heat seemed normal. Blower kept going till 1/2 way home which is a lot longer than it usually stays on high speed.
Is there some kind of temperature sensor I can look into? I have MB DAS/Xentry and am thinking I should see what interior temp it is reporting and compare that to a thermostat I place on the center console of the car.. just to see if there is a different.
I assume the system is getting its readings from the coolant system (to tell coolant temp), evaporator, and some kind of "interior" ambient sensor combined with a sunload sensor (to adjust heat/cool when the sun is beating down)
Do these interior sensors get gummed up and need cleaning? Do they fail?
02-26-2016, 07:00 PM
#2
For heat I suggest to turn up the footwell temp aggressiveness via the hvac menu in the center console.
Otherwise, yes you can read with das the hvac module and see if it throws any sensor implausible errors.
Otherwise, yes you can read with das the hvac module and see if it throws any sensor implausible errors.
