Air Condition "Auto Fail"

[whiggy 2]

Hello! Sometimes, I get the "Auto Fail" Led on during cruise flight. I think this mean a problem with air condition.After a time, the Led goes off. What is the correct reaction todo when this problem occurs?

[davierosoft 13]

When you have AUTO FAIL you will have also the aural warning with beep beep...AUTO FAIL is linked also to the air conditioning but is not airconditioning light.AUTO fail is a pressurization control light, when is ON there are 2 reasons.The first one, te most common, is an user error, the second one maybe related to a failure if failures are selected.When it comes on do you hear the beeps?Make sure both packs are in AUTO position and bleeds are ON for engines.

[trisager 2]

There is a checklist in the QRH for this, starting on page 2.2. The first actions are to verify that both bleeds are on and both pack switches are in auto.

[whiggy 2]

I don't get any beep.Failure simulation is off for all. I get only the light on.Booth packs are auto and bleeds are on. (except APU bleed)

[davierosoft 13]

Post a screensot when you have the problem, is the problem shown in climb or cruise? What about pack switches? Are they auto, off, or what? Bleeds?

[whiggy 2]

Bleeds autoPacks auto It occours @ cruise.

[davierosoft 13]

Maybe you mean bleeds ON, as there is no AUTO position for them.I think you must post a screenshot of the overhead panel when it happens, the screenshots must contain a clear view of the panel and pressurization gauges as we must see if pressure inside the cabin is strange.

[ArjenVdv 190]

I also had this a while ago. It turned out I simply forgot to put the Packs back to AUTO after engine start. When I did that, the AUTO FAIL light extinguished.

[davierosoft 13]

Maybe here the problem is different as there is only the light that comes on and no alarm, all appens during cruise, so the plane pressurizes correctly ten something is going wrong...

[XCLTM3 112]

Maybe here the problem is different as there is only the light that comes on and no alarm, all appens during cruise, so the plane pressurizes correctly ten something is going wrong...

Hi Andrea, just to let you know that I have experienced this from time to time also. Despite the fact that I carried out all the necessary checks, everything was in place but still occassionally the Auto Fail message appeared. I can tell you that what I discovered was that "Winds Aloft" particularly at cruise level affected it. There is no doubt about it. I'm not certain that what you are experiencing is precisely the same, but if you have carried out all the appropriate checks and everything is in order for certain.......then look at your winds aloft....are they gusting? See what you come up with. Rgds, XCL

[Piotr007 164]

I have many times this Auto Fail with orange illumination.

 

And it happens on gusty flights as well, it does not happen in calm weather. What is the cause of this auto fail? It seems a bug to me. Packs are on auto and the engine bleeds are on.

It does not suppose to occur.

 

Moreover, if this is a bug it should be addressed in SP2.

 

Peter

[JOR 0]

It happens when your cruise alt doesn't mach with the given alt on your upper panel. Just adjust it to your cruise alt and it'll go away.

 

Reg,

John

[Piotr007 164]

It happens when your cruise alt doesn't mach with the given alt on your upper panel. Just adjust it to your cruise alt and it'll go away.

 

Reg,

John

Thanks.

 

You mean the altitude panel near the pressurization gauge on the overhead I guess?

If so, I have to adjust it to cruise ALT when on the ground. In flight it's -------------- and unable to be adjusted.

 

Thanks for explaining anyways. I wanted to do that, but it was just impossible inflight. No matter how I turned the knob.

 

Regards,

 

Peter

[JOR 0]

Yes, that's the one.

 

It should be the same as programmed in your FMC. I Always set the alt when programming the FMC. But you should be able to adjust it also inflight. Sometimes you get another FL then filed and programmed. Then you have to change both.

[Ralgh 43]

An amber AUTO FAIL light illuminates if any of the following conditions occurs:

• Loss of DC power

• Controller fault

• Outflow valve control fault

• Excessive differential pressure (> 8.75 psi)*

• Excessive rate of cabin pressure change (±2000 sea level feet/minute)*

• High cabin altitude (above 15,800 feet).*

*If controller is not responding properly

 

You should not get AUTO FAIL if you fail to set the FLT ALT properly. Also the intermittent warning horn comes on when the cabin altitude reaches 10,000 feet, not when the AUTO FAIL light comes on though if you do get AUTO FAIL and the ALTN light does not come on you may then get a high cabin altitude.