[dlmcdowell]

My rear air conditioning and heating on my 04 does not work except on cold on the highest level. It does not work on any of the heat settings or the two lower cold settings. The front air con and heat are fine.

I took out the air filter and the problem remains when it it removed.

Any ideas on the problem?

 

[dlmcdowell]

So it looks like the vents up top are for a/c only. So the high a/c works, but not either of the lower 2 settings...

 

[OdyinNH]

Yes, no heat comes out the top vents. There are low ones for heat. Maybe the speed control resistor is bad, no clue where it would be though.

 

[dlmcdowell]

The speed control resistor idea looked like a good one as I researched it more. I got one delivered and replaced it. Unfortunately, it didn't fix anything. Any other ideas?

 

[DZD]

when you say it doesn't work - are you referring to the fan coming on or off? On Low or Med AC does the fan come on but not cool? Does it make a difference if you use the Rear Controls or the Front Controls (for the rear)?

 

[dlmcdowell]

Good questions. The rear does not come on at all when I turn it on low or medium (from either the from or rear controllers). I do hear a click when I try on low or medium, but no air. On high, it does work (from either controller)...

 

[William Wiles]

Did you replace the resistor board in the rear AC unit or the speed transistor in the front? Does the heat act the same, only blows heat at the floor outlets on the high setting. If you did replace the rear resistor board then you need to revisit it and voltages with a meter. The board should have 12 volts when not selected and drop in steps to zero when high is selected. If the board is ok then you are going to need someone with electrical troubleshooting knowledge to trace the circuit.

 

[DZD]

Could it be that the fan itself is broken and only works on High?