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Is it possible to calibrate the AC climate control thermostat?

15K views 18 replies 11 participants last post by  thx1200  
#1 · (Edited)
Ahh... Fall and Spring -- the two seasons with the finest weather!

I live in the south, so during the summer (which is when I got my Smart), I pretty much kept the AC to the bottom notch -- the one below 60 -- which basically tells the system to blow the coolest air possible all the time (and turn on recycle air automatically when more cooling is needed -- awesome).

Now that it's fall, this is the time of year I generally keep the AC on to combat the humidity, but mix a little heat to make it comfortable.

What I've noticed is that at the 60 degree notch, just one notch above maximum cool, the blowing air is too warm for me! I'm practically sweating. it's certainly not giving me 60 degrees. I'd guess the blowing air is 65 at the lowest, which means when you factor in the heat from the sun that the cabin is maybe 70-75 (definitely nowhere near 60). In my house I have the AC set at 70 and it's comfortable for me, so there's no way my Smart is doing 60.

I could take it to the dealer under warranty, yes, but I'm just so much of a do-it-yourselfer! Does anybody know if there is a way to calibrate the climate control to make the temperature range cooler? It's probably deep in the bowels of the car's computer, but I'm hoping there's just a little potentiometer hidden somewhere for me to fiddle with to adjust the interior thermometer.

I'm cold natured and I live in the south, so I'm not too worried about it not being hot enough in winter. :)
 
#4 ·
Thanks a lot! I'll double check when I drive home tonight. I'm pretty sure nothing is in front of it, though. Maybe I need to put a mirror in to reflect the infrared to my overheating torso so it cools me down more. ;-)

EDIT: I wonder if I could rig in a little potentiometer to affect the current returned by the "eye" to fake the Smart into using a different temperature that's more comfortable for me. HMMM... :)
 
#7 ·
I can vouch for the auto recycle functionality. :) However, I've never been in a car with an auto climate control that actually worked in any useful fashion (Subaru, Honda, etc.). It always just seems like a gimmick that never pans out as advertised and the smart doesn't seem to be any different. Just give me a temp slider, vent, and fan control. I always leave the temp slider in the lowest setting on the smart and just change fan speed/vent selection to suit.

IMHO, smart would probably be better off saving a few bucks by cutting this functionality altogether (it is a small economy car, after all) and putting it into something more useful like a longer standard warranty, better OEM stereo, factory cruise unit, more color choices, improved trans, etc.
 
#6 · (Edited)
OK, are we sure that the "thingy" isn't BIG BROTHER watching? :cool:

I though it was a light sensor that simply detects sun up or sun down?

Most other vehicles have such a thingy mounted on the dash and it senses day/night and makes minor adjustments to the air conditioning.

And in the South, having your thermostat set at 60 degrees the system will never cycle until you see snow on the ground as this is a very small engine with an even smaller air conditioning system.
 
#10 ·
Okay so I double checked the infrared and nothing is in the way. I guess short of anybody knowing any way to calibrate the sensor, I'll be giving the service center a call to see what they say.

rfernatt - I completely agree. It never seems to work right. I was hoping Smart's would be better since I find the car otherwise is, despite it's economy, really very high quality. They could at least have an "auto" switch that toggles between the old school slider and thermostat mode.
 
#12 · (Edited)
Consider this - the sensor reacts to what it sees, and it looks right back between the seats and some part of whoever is sitting or not sitting in them.

(1) Hot day, and occupants' centerline arms are uncovered and registering 98.6F - sensor says "cool that down a bit."
(2) Similar day, but arms are covered in light fabric - sensor sees the effect of the A/C on the fabrics' surfaces and says "not-so-bad, no intervention required."
(3) Cold day, and the occupants are regaled in synthetic-over-down jackets - sensor says "surface temperature is cold if even the occupants are not, go for more heat."
(4) Similar day, and the occupants wear good wool sweaters that absorb and hold warmth - sensor says "it's warm back there; heater don't bust your hump."

I don't know the sensor's cone of view.
 
#15 ·
Consider this - the sensor reacts to what it sees, and it looks right back between the seats and some part of whoever is sitting or not sitting in them.

(1) Hot day, and occupants' centerline arms are uncovered and registering 98.6F - sensor says "cool that down a bit."
(2) Similar day, but arms are covered in light fabric - sensor sees the effect of the A/C on the fabrics' surfaces and says "not-so-bad, no intervention required."
(3) Cold day, and the occupants are regaled in synthetic-over-down jackets - sensor says "surface temperature is cold if even the occupants are not, go for more heat."
(4) Similar day, and the occupants wear good wool sweaters that absorb and hold warmth - sensor says "it's warm back there; heater don't bust your hump."

I don't know the sensor's cone of view.
Shouldn't affect me. I'm still wearing a t-shirt and shorts, just like in summer. If it's bouncing off my arm (not sure of the cone, as you say), it should be reading my body temp. I would think they would engineer it to account for that, though. That would seem to be a pretty common scenario.
 
#16 ·
Now it's sufficiently cool out that I want more heat. I am finding the exact opposite problem. lol. For 60-79, there's barely any difference, but then 80, holy cow here comes the flame thrower!

I think I may have an actual thermostat issue and not just a random calibration issue. Going to call the service center. :)
 
#19 ·
I don't think that's right. From my tests, the compressor always turns on with the AC button -- this gives you dry air, which helps defog windows. Additionally, the AC never automatically turned on in summer (as in, set point was 60, but it's 95 out, it just blew the fan, but no compressor).

You can tell when the compressor kicks in by a quick dim of the lights from the extra current needed to crank up the compressor, plus actual mechanical noise if your window/top is open. I have never seen it not come on, even now with colder weather here. Winter conditions remain to be seen!

Recycle, however, engages anytime it's over like 10-15 degrees over the set point. You can tell by the increased interior fan noise. Hit recycle, no change. Hit it again (turn it off) and it goes to a quieter level (no recycle). Remember, when you recycle air, you are adding a lot of extra fan noise / turbulence, so it's easy to listen for.

If you go up a hill or put pedal to the metal, your compressor, however, will turn off, to give you the extra juice you need to get going.