Weird Issue with Heater/Air con

[low_vr4]

So the last few weeks i have been having an issue where, as soon as i turn my car on the heater comes on full blast. The heating is turned off and will not do anything at all.

Sometimes it turns off after a few minutes.

I have tried taking out the fuse but it makes no difference.

Any idea?

[crazydriver81]

Can you take a picture of the A/C controls display?

And what do you mean by "...the heater comes on full blast. The heating is turned off and will not do anything at all..."? I undersatnd that the blower motors run on full speed with A/C switched on? I think this is the normal setting, when battery was disconnected.


Could very well be, that the A/C control panel has an issue (bad soldering etc). It sounds to me, as if the A/C control panel does "forget" the last settings (like your stereo will do if it has no constant +12V source). I'd try with a different A/C control panel first to rule this out.

[Davezj]

I think this is good advice.
Does you stereo loose it's memory for the radio stations. As this could indicate a fuse for the acc 12v has blown which would tie in with the constant reset to default a/c settings.

Just a thought.

[Subaru ETA]

Agree. It sounds like it is loosing its power feed so loosing its memory

[CANDEE]

Make sure the plugs are in 100%, as one of the plugs not plugged in can cause this as well.

[John TheAntique]

And make sure the black finger thick hose on the back has not come off and disappeared down the back somewhere. I this happens it gets confused.

[Davezj]

And make sure the black finger thick hose on the back has not come off and disappeared down the back somewhere. I this happens it gets confused.

this is a good point, the hose draws a small amount of air from the cabin over a temp sensor behind the grill under the temp control knob and it uses this to adjust the heating/cooling when in auto mode.

[low_vr4]

I will take it all apart this morning. One thing i did notice when i was fiddling with the controls, was that when i checked the temp it was was sitting at -30 degrees.

[crazydriver81]

I will take it all apart this morning. One thing i did notice when i was fiddling with the controls, was that when i checked the temp it was was sitting at -30 degrees.

This is a sign of the failing of the outside temp sensor. However, it may be that the plugs on the A/C unit are not preoperly seated. Push them all the way in until you hear them "click"ing in. The last mm can be hard though and you probably didn't notice when you were fiddling with the controls...

[low_vr4]

Is it possible to disconnect everything? I have never used the A/C or the heater in 4 years so may as well disconnect it all.

[crazydriver81]

You can leave the stuff disconnected but then you have no control for the blower motors too, and no rear screen heating. Have you checked the plugs yet?

[wintertidenz]

See if you can borrow someone else's A/C control unit as well to see if this is at fault.

If it is, I don't think they are expensive from Pick a Part.