ZONE TEMP LIGHT / QRH

[Jeff_B 8]

Hi all, had the zone temp warning light come on during a flight (aft zone) and thought this is great will refer to QRH to determine fix/solution. However in QRH index for zone temp says to go to 2.42 but all they mention is Autofail light & pressurisation which wasnt any help as it talks about steps for manual presurisation etc etc, no mention on the zone temp light or how to action work around to extinguish/solve the problem. i didnt have pressurisation problem that was all as normal. Any clues/feedback anyone.

[henkie 0]

2.24 ZONE TEMP Make sure you're looking at the correct page.

[Jeff_B 8]

2.24 ZONE TEMP Make sure you're looking at the correct page.

Sorry that was what i meant.Did you have a look - no mention of zone temp.

[henkie 0]

That is strange because in my QRH they are telling you to select a cooler temperature, push the TRIP RESET switch and to put the TRIM AIR switch to off in case the duct temperature is increasing rapidly.

[vlanz 0]

Same as a -400, what he said^^

[Maximilian_Groeber 0]

Well, I recentliy discovered a nice solution ;-) I always had the "zone temp" warning too as soon as the engines were running... Just try this: As soon as the engines are running and bleed air is used for air conditioning, rotate all temp knobs a little bit (counterclockwise if you want to lower the duct temperature) and if it's rather hot outside, switch off trim air. Then wait a moment until the duct temperature stabilises and turn the knobs back to their former position. It works perfectly for me! Afterwards I can tune the temperature very comfortably. No zone temp issues (at least, as long as the outside temperature is not too high) and the duct temperature doesn't rise above all limits as soon as I turn any knob just one little click... Maximilian Gröber

[Jeff_B 8]

Well, I recentliy discovered a nice solution ;-) I always had the "zone temp" warning too as soon as the engines were running... Just try this: As soon as the engines are running and bleed air is used for air conditioning, rotate all temp knobs a little bit (counterclockwise if you want to lower the duct temperature) and if it's rather hot outside, switch off trim air. Then wait a moment until the duct temperature stabilises and turn the knobs back to their former position. It works perfectly for me! Afterwards I can tune the temperature very comfortably. No zone temp issues (at least, as long as the outside temperature is not too high) and the duct temperature doesn't rise above all limits as soon as I turn any knob just one little click... Maximilian Gröber

I tried all that with no luck it still stayed illuminated and the temps did not increase or decrease. What i find eeven more odd is my QRH had no mention of zone temp as someone mentioned with no work arounds, just no mention. I must have those pages missing. I ordered the chief pilots set on day 1 maybe they were corrected/revised but mine certainly doesnt have that info.

[Jeff_B 8]

Have you cancelled the Master Caution on the FO side ?This is tied in with the logics and needs to be reset.

Certainly did JasonG

[nj1044 0]

Hey Jeff, Try a pre-emptive strike on this quirk: crank the zone temp down all the way to "C" when you start the APU or about T-minus 3-5mins if you run it from the start. Then set them back to AUTO before taxi. Also, leave the recirculate fans on during eng start; just kill the PACKs and you're good to go. Turn off the APU bleed air immeadiately after the engines are stabilized, even before u set the APU switch to off. I don't know why but this seems to help. Finally, open as few doors as is necessary. PMDG modeled the cabin heating up/cooling down more quickly with more doors open(cool, huh?). I hope this helps. Regards,-Nate

[Spin737 102]

Try a pre-emptive strike on this quirk: crank the zone temp down all the way to "C" when you start the APU or about T-minus 3-5mins if you run it from the start. Then set them back to AUTO before taxi.-Nate

Interesting point: the "C" position is still AUTO, it's just the cold end (65F/18C).

[Spin737 102]

So does that mean that "W" is still auto but just the high end ?

In fact, it does. Some people (including an instructor I had a few months back) believe the 12 o'clock position is AUTO. That's just where the word "auto" was printed on the panel. AUTO has a range from C (18C) to W (30C). Much like your home thermostat. But a few hundred times more expensive.

[Jeff_B 8]

Thanks to all above will try next time i come across this. Lot of good info thanks.

[Jigsaw 8]

In fact, it does. Some people (including an instructor I had a few months back) believe the 12 o'clock position is AUTO. That's just where the word "auto" was printed on the panel. AUTO has a range from C (18C) to W (30C). Much like your home thermostat. But a few hundred times more expensive.

But... but... but... when you can set the desired temperature manually from such a wide range it's not really AUTO, is it? Someone should tell Boeing that!

[nj1044 0]

Thanks for the input Matt, I'm very definatley still in learning mode. So its a automated climate control system wherein the pilots dial in a desired temp, not a spectrum where "C" is the coldest possible output and "H" is the hottest. Good to know. Also, my thoery should still work: if the problem is anoverheated cabin after engine start, then starting the engines with a colder ambient temp should fix the problem. However, I dont understand what causes the temp spike in the cabin during/after ignition... So if the answer isn't too complicated, why can zone temp anns be tripped shortly after engine start even with the PACKs on? Any recommended fixes? Highest regards-Nate

[Spin737 102]

But... but... but... when you can set the desired temperature manually from such a wide range it's not really AUTO, is it? Someone should tell Boeing that!

You also manually engage CMD A and CMD B for the autoland. The controller automatically maintains the desired temperature by moving the pack valves and trim air valves. The -700 has a manual mode where you are driving the air mix valves and you get whatever temperate you get. It makes more sense if you've seen the nomenclature from the other planes.