Heat stuck on / Air mix motor operation in 98 EXV6
 

The other day I was getting hot air in the cabin regardless of the dial setting on the climate control.

Long story short, it seems something is up with the air mix motor OR with the head unit controlling it. Since the air mix motor is a $120+ part, I'm trying to confirm before replacing it. With the motor removed, I verified that the blend door moves smoothly, as does the cable which attaches to the coolant valve under the hood. So I don't think either of those is binding up.

When I move the temp dial from full hot to full cold, sometimes the motor moves right away, other times it just sits there and moves 10 or 20 seconds later, and sometimes not at all. I know there are temp sensors somewhere in the mix. Is it possible those are causing the lag, or is that just a sign of the motor going bad?

I tried the DTC and it shows no errors (nothing on the display). I tried again with the motor unplugged to verify I was doing the DTC procedure correctly and it showed an error on the motor assembly. Plugged motor back in and tried again - no error.

Probably I should try to test the motor directly but I'm not sure how to "connect battery power to terminal 1 and ground to terminal 2"

Thanks,
Tyler

Take a wire ( pick a color- black) and connect one end to the battery + positive.
That the other end of the black wire and connect it to terminal 1 ( there should be a mark or label "1" on the connector.

then take a 2nd wire ( pick any color but black - pick say red) and connect it to the neg - post of the battery (note: - or negative is also "ground"). attach the other end of the red wire to terminal 2 on the motor.

If you can, post a picture of the motor and the connector, where we can see the marks. I can help you more if I can see how it is labeled.

But terminal 1 = pos or + of the battery

terminal 2 = - or neg ( which is also Ground) of the battery

Thanks. I wasn't sure if I could just take the motor over to the battery and do that. I haven't tried this yet because I didn't find something to easily hold the wires onto the motor pins.

I did play around with things a bit last night and it seems that the water valve control cable movement is restricted by the metal clip that holds in in place under the hood. I'll try to add a pic later. If I undo the clip, the motor seems to respond to dial movements immediately and every time. If I fasten the clip the motor sometimes will not move or the movement will be delayed. In both cases, the cable is still hooked to the water control valve and it operates smoothly, albeit with enough resistance to hold it's position even if the cable were not attached. There must be a little bit of drag added by fastening the metal clip, but I'm not sure how to remedy that.


For now, I can leave the clip undone and the things seem to be operating ok.

Show us a pic of the clip. Maybe the clip is too tight and you can bend it a bit to loosen it up and hold the valve in place, but that it is still loose enough to let the valve rotate.

The clip doesn't seem like it would change tightness over time, but maybe it has. I took two pictures so you can see unclipped and clipped. I can probably get just the clip and see if a new clip helps. Otherwise maybe there is a way to lubricate the wire in the plastic sheath.

Or, I'll leave it unclipped - it seems to work ok that way.

It looks like the water valve control cable is less than $10. Maybe I'll just replace the dang thing.