00 XC 70 A/C only works on defrost (solved with used ECC control unit) Topic is solved

ems_kws · Post by **ems_kws** » 09 Jul 2017, 19:06

I've never dealt with an A/C issue before so I am searching other threads and trying to figure this issue out.

The A/C only turns on when the defrost is selected. I can leave it on that setting all day and it will run fine but it turns the A/C off as soon as I select the dash vents. What gives? Where do I even start? Its 100 out and my pregnant wife really needs good A/C.

Post by **abscate** » 09 Jul 2017, 19:39

When you touch the AC button does the LED light? Also, on start up do the two LEDs for recirc and AC flash for 20'seconds?

ems_kws · Post by **ems_kws** » 10 Jul 2017, 14:06

The A/C led will come on if it was left on the defrost setting. I just checked and none of the lights flash on startup. If I start up with AUT selected on the vent instead of defrost then no A/C led when I push the A/C button.

Post by **abscate** » 10 Jul 2017, 14:36

It sounds like you have localized it to the control unit of the ECC, Can you try a pick and pull spare.

I'm guessing it's warmer than 32F in NV, so it's not temp.logic.

ems_kws · Post by **ems_kws** » 10 Jul 2017, 14:55

Just reading about all the sensors and related A/C part I'm wondering if it is getting faulty inputs from one of them. This system seem rather complex.

ems_kws · Post by **ems_kws** » 11 Jul 2017, 13:37

Had an interesting development int the A/C issue.
Headed into town last evening and when I started the cat the climate control was on AUT where I had left when I checked for flashing leds. A minute down the road I switched it to defrost so the A/C would run and it ran through the dash ducting even though the defrost was selected. Then I switched it back to AUT for testing and it switched the A/C led off again. Is this consistent with a bad climate control unit? I've found them for 30 bucks off Ebay but who knows if they are any good.

Post by **abscate** » 11 Jul 2017, 13:40

The AUT function is sticky, and remembers where you left the AC either on/off when you override it with one of the other controls. DEFROST always forces AC ON, so thats why it is turning on then.

Your ECC knows you want the AC off and is stuck there.

Alas, Im not sure that is a definitive ECC control unii failure diagnosis.

ems_kws · Post by **ems_kws** » 21 Jul 2017, 16:44

abscate wrote: ↑10 Jul 2017, 14:36 It sounds like you have localized it to the control unit of the ECC, Can you try a pick and pull spare.

I'm guessing it's warmer than 32F in NV, so it's not temp.logic.

Bought a used one off eBay and it appears to be worki.g gone now. Thanks

Post by **abscate** » 21 Jul 2017, 19:10

Nice. Thanks for the report back. That helps the next guy !!