Hi, I'm having issues with the climate control in my S40. The car heats up fine, never overheats, dash shows outside temperature accurately.

Issue seems to be the automatic climate control.
No matter what I set the temperature or fan speed to, the car heats up, heat comes on full blast for 20-25 minutes and then blows ice cold for the rest of my drive. drive.
also the blower will randomly change speed .
It's like the climate control has no idea what it should be doing.

Is there a sensor I should look to, or is this a replace the whole climate control situation?

Thanks in advance,

Joe

 

do you see anything like a flashing ECC or REC light that indicates there's a fault code stored? Yes there are temperature sensors, as well as a blower controller, relays, blend door motors etc that can all be at fault so best to have the ECC scanned to determine what's going on. Or you can simply replace parts and hope for the best...

My suggestion is to start googling for forum posts etc on the general topic of S40 climate control design/functions and go from there.

Example: https://www.matthewsvolvosite.com/fo...ic.php?t=44355

 

Hi, thanks for your answer.
There's no check engine lights. I've scanned it. No codes. It's been like this for a long time and it hasn't affected the running of the car in any way. I know there's an ambient sensor. On the mirror I think. It would cause the temp on the dash to read incorrectly. The whole climate system is wonky. That's why I was wondering about a cabin sensor.

 

not all scanners can read all code sets (like the Bxxxxxx CCM codes) so you may need a shop's assistance. Do the lights on the REC and AC power button come on and change colors? If the temp sensor was reporting as open or shorted, I'd expect a code to be set.

Have you had any issues with sun roof drains (ie wet carpet after a rain) that could have allowed water to get in behind the dash? Thinking you may want to clean/reseat connectors to the ECC and CEM, blower motor etc.