Heater blows hot and then cold repeatedly

dpayne20 · Post by **dpayne20** » 13 Jan 2019, 22:15

Hello, The heater in my 2006 volvo s60 2.5t blows hot air intermittently over and over again. It will blow hot and then cold in periods of about 4 seconds. I have filled the coolant to know avail. any ideas would be helpful, thanks

Post by **RickHaleParker** » 13 Jan 2019, 22:35

Check the damper and see if it is moving. For a 4 second change it got to be blending of hot and cold air. A heater core cannot change temperature that quickly.

dpayne20 · Post by **dpayne20** » 13 Jan 2019, 22:36

How do i check the damper?

Post by **RickHaleParker** » 13 Jan 2019, 22:52

Up under the dash, right side. Check to see if the motor(s) are moving in sync with the temperature change and listen for internal flaps flopping around.

: Damper_Motor.gif (80.62 KiB) Viewed 3566 times

dpayne20 · Post by **dpayne20** » 15 Jan 2019, 13:52

Ok I checked it, the arm moves a couple of times and then stopped, I tapped on the motor a couple times making another arm move a little and go back in place, now to passenger side still works great and the drivers side heat work up until the max heat notch and it goes back to goi g between hot and cold. Could it be the damper motor or is something in the way of the arms or is it a software issue that volvo could fix with a update?

Post by **oragex** » 15 Jan 2019, 15:42

Maybe the climate unit needs recalibrated or the cabin temp sensor has a problem. This sensor can get damaged when the battery is connected without having the key in Pos II

Post by **RickHaleParker** » 15 Jan 2019, 19:17

Does the arm movement correlate with the changes in temperature?

dpayne20 · Post by **dpayne20** » 15 Jan 2019, 19:18

Yes it does

dpayne20 · Post by **dpayne20** » 15 Jan 2019, 19:41

Everytime the tempature changes there is a buzzing sound in the dash

dpayne20 · Post by **dpayne20** » 15 Jan 2019, 21:01

Also it seems that I can recalibrate whatever is making the buzzing sound by taking both temperature dials and putting them to cold and then going back up at the same time, but when I restart the car the buzzing starts again and it gets hot and cold along with the sound