The dealer recently replaced the radio/climate control unit in my 2005 TL. Since then the temperature setting within the car needs to be set about 4 degree's higher, 26 versus 22 (Celcius), for the cabin to feel as warm as it did prior to the unit being changed.

It appears the new unit is not calibrated correctly. Is there is any way to check/adjust it without having to return to the dealer?

 

Oddly enough the service manual does not mention temperature calibration at all in it's HVAC section. It does mention a daylight sensor. What's that for, and if it can selse daylight why the hell am I turning my headlights on and off manually?!?!?!!

There's a method for testing the sensor, but it's too complicated for a mechanic to follow, matching ohm readings to degrees farenheit. If you had someone with a background in elec engineering you could adjust how the sensor outputs its signal by adding a resistor inline or parallel to match the table, but its going to be alot of work. I feel for ya, but I would just settle with it if I were you. It took me a while to find a good temperature I like, and I still don't believe its really 68 degrees that feels that comfy, but i just keep it there.

In the event you do have an elec engineer buddy, he might find page 1453 (21-66) of the service manual handy. I would upload that page, but I respect the copyrights of Honda and Helms alot more than whoever uploaded the whole manual to rapidshare here http://rapidshare.de/files/7599227/TL_Manual.pdf.html

 

The 3 acruas I have had were all different in this regard. I typically would set the temp and forget about it. The cars were as much as 3-4 degrees off from each other. I spoke to the service manager, saying I was curious as to why the difference. You get used to one setting for a few years and then find yourself using something 4 degrees different. He just shrugged and said use the different temperature setting is all.

I am sure all the units have some variance to them. If you figure +/- 5% that could account for a difference between the units.

 

The sunlight sensor is not there to measure temperature - it helps the AUTO system determine "heat load" from daylight (greenhouse effect) so the system can make an informed choice of temp/fan speeds. The NAV system can also provide input to the AUTO system.

Anything can be claibrated, but frankly, this strikes me as trivial - set the thing so you are comfy, and fagedaboudit - I am listening to the SACD of DS' Brothers in Arms..."Why Worry?". Really, why worry, as long as the system is doing its job otherwise?

Mickey3c also makes a good point - any mechanical or electro-mechanical system has an accuracy/tolerance level in it - a Rolex is a "Superlative Chronometer", but that means +/- 10 secs a day or so. Most capacitors have anywhere from a 5-20% tolerance rating (I use 2% Panasonics in critical precision network designs, with 1% resistors). If the network is critical, we ise laser trimming.

 

All perfectly true comments about variances between cars.

My 1G TL was perfect for us at 73, and when I got my 3G it took a while to realize that I needed to set it at 70 for the same effect. Another 3G might need a different setting for us. Someone wrote in and said he kept it at 67, which would freeze me out, but maybe his 67 is my 70.

So bite the bullet and set it where it's comfortable. It's not like you have to change it every time you get in the car.

 

All I wanted was the same temperature indication as before. Dam; sometimes I just hate being a anal attentive!

Have a great one.

 

I'm probably more anal than you, but some things you just have to accept the way they are.

Anything that diminishes from my enjoyment of my TL gets put on the back burner.

 

I agree, pick the things that really matter to get upset about. While this would be annoying it just isn't significant enough to get smoked about it.

Curious though. With the incredibly tight tolerances manufacturers can attain (low variance) these days it's odd that you would see this variance the climate control system in the car. Oh well...