EATC Not Working

[MarkDex]

1995 EB 109,000 miles

EATC was acting erratic but now will only allow air to blow up through the defrost vents. Pushing any of the modes buttons has no effect. Also, no diagnostics appear when I put the EATC through its self test.

Any advise is greatly appreciated.

Thanks.

 

[daffy]

From what I've read this is usually a vacuum leak, sorry I can't be more specific, as I've never had that problem, but people often site the vacuum canister as being at fault, I think on a 1st gen explorer, it's in the passengers wheel well.

 

[MarkDex]

Thanks Daffy!! I found a vacuum connector that was completely loose from the vacuum chamber (under the air intake on the passenger side). After reconnecting the air distribution control is working again.

However, I will have to wait until it warms up here in Colorado to see if the temperature control is working. I suspect that the blend door motor and/or actuator may have failed.

Any suggestions.

 

[daffy]

you could manually set the temp high and low to see if it switches

The blend door has been written about by many many people, search for the blend door and read all you can. Hopefully it will be a long while before I have to tackle it.

 

[MarkDex]

I have tested the temperature settings. When set to 60 (max cooling), I get good cooling. When set to 90 (max heating), I get good heating. However, when the outdoor temperature was 57 and temp setting set to 69, I am getting what seems to be erratic behavior. The system will cool for a while through panel vents and then change to heat through the panel vents. When I put the into Vent manual mode, I get hot air through the vents.

I have also removed the blend door actuator to test. When removed put reconnected to the wiring harness and temp setting changed, the actuators post is moving smoothly. Also, I was able to look with a mirror into the plenum the hole for actuator post. It seems that the blend door shaft is still intact.

Does this seem like a blend door problem or a interior or exterior temp sensor error? I am still not getting any error code after the EATC is put through its self-test diagnostic mode.

Thanks for any help.

 

[daffy]

I know there are 2 sensors in the interior, 1 on the back of the mirror (for sun correction, I think) and one in the dash, to the right of the rear wiper control (looks like a little vent), maybe one of them is blocked/partially covered? I know when my wife blocked the one in the dash with her coat, the EATC just cranked the heat until we uncovered it.

 

[MarkDex]

Well, I finally got the EATC to display an error code "025" which is an intermittent code for a failed blend door. Sooooo, I will be spending 5 hours taking the dash off to replace the door. But first I will check the actuator again to make sure that it is still working.

 

[MarkDex]

I have bought a Blend Door Repair kit from NAPA but it did not come with any installation instructions. Does anyone have any good tips to installing the parts that come with this kit?