No Driver Heat - 1998 Volvo S70

Tbourvolvo · Post by **Tbourvolvo** » 02 Jan 2025, 11:38

Been fighting this issue for a long time. I can't get any heat (cold air only) on the drivers side of the car. I have confirmed heat on the passenger side works. The damper system seems to work moving air from floor to vents to defrost. I currently don't have any ECC codes or flashing lights. The temp senor seems to be moving at it should (rotating). Heater core seems to be working fine. Is there any way to check the dampers without removing the entire dash? Things I have tried so far... 1) removed the damper motor on DRIVER side (the one way up in there or the harder to reach one) and tried to manually move the damper. it spins but I don't notice any change in temp. 2) Checked ECC codes with VOLVO FCR on the control module. Nothing comes up. 3) checked heater core temp incoming and outgoing lines seem to be normal 4) checked air temp sensor. Seems to be working and fan rotating.

Post by **scot850** » 02 Jan 2025, 15:50

The heater core is always hot. There are no valves on the core. It is how the air flow is being routed that confirms where the air goes and if it is hot or cold. When you had the servo motor out, did you check the motor moved?

I just did that on a 97 850 as they have an issue with breaking the flap connection between one of the motors and the motor. Problem was I had no idea where the motor was sitting when I fitted the new flap was fitted as it was moved after it broke. Fortunately I did as I found it was 90 degrees out.

I can't recall having that issue with a V70 98- car. The motors do fail, but as you have hot air on the passenger side and not the driver's there is either an issue with one of the motors on the LHS or, an ECC control issue.

I know that motor you removed was a pain, but you can test it with it removed to see if it is working.

Remove the motor and use a marker to make a mark on the motor body and on the square shaft. aligned with it. Turn the knob on the ECC (car ignition on II position) to move the air from say floor to windshield or floor. Does the motor move? If it does, return it to where you started from and make sure when re-fitting it that it is fitted in the correct position to move the flap in the correct direction.

Our friend Robert has a few comments in this video:

Neil.

Tbourvolvo · Post by **Tbourvolvo** » 06 Jan 2025, 07:15

Thanks for the reply. I can try and mark the motor. The motor on the LHS is OEM new from Volvo. It does turn when plugged in. Currently the motor is off/disconnected, and we tried to manually move the damper it spins but not seeing a change in the temp and get heat all the time as it's winter here. It's been pretty cold this week in the Midwest, I will try again when it warms up this week.

Post by **scot850** » 06 Jan 2025, 08:35

Unfortunately, we only find these issues when it gets cold.

The issue my friend found with his 97 Volvo was when I took it apart, both mounts on the LHS were broken off which moved the air to under the dashboard and not to the windshield and door glass!

I've been trying to find a layout drawing for the 98- cars to identify which/why you are not getting heat on the LHS. So far no luck, but I'm sure there was one I found a few years back.

The issue could be the ECC unit itself.

Neil.

Tbourvolvo · Post by **Tbourvolvo** » 06 Jan 2025, 10:34

I guess my real question is, Do I need to take entire Dash off to watch the dampers function on the Driver side? I was hoping only the dash cover needed to come off. I am not certain you can see down with only the cover removed.

Tbourvolvo · Post by **Tbourvolvo** » 27 Jan 2025, 12:39

Just a quick update. Thanks to those that responded to this post. I don't have my issue solved yet but made some good progress and verified my issue. Hopefully this helps someone else on the forum. I decided to by a cheap borescope off Amazon for less than $80. I was able to remove the center air vent cover (dual one) and look down at the dampers as the car was running and changing the temp and directional dial (floor / vent). I could see the directional damper was working as it should. Using the borescope I looked down the passenger side of the air vent and could also see the lower damper move while changing temps. Using the passenger side (heat and temp working), I could verify the correct position of the lower damper to provide heat. I then looked down the left side of the center vent to see what the driver one was doing. This is the side I can't get heat. Sure enough, the damper is stuck in the wrong position only giving outside air and would not move when changing the driver side temp dial. Next step will be to manually move the damper watching on the borescope if it moves by rotating the black fitting. If I get heat then, I will try to hook up the stepper motor again and test using volvo FCR.

Post by **abscate** » 27 Jan 2025, 14:47

You can drive the motors with a 9V battery safely, if you get a junkyard hardness to plug into the motor on the car.

You might find a happy place you can leave the heat on for the winter to make it liveable