737-900ER Temp Selector Anomaly
 

In 2016, an airline prohibited the OFF position on the temp selectors to prevent a fault with the E-Flow Electronic Pack Controllers.

Did your airline do this? Was there a fix?

I recently read about this in one of the 737 tech type apps, but I’ve never seen anything official from our operator.

A lot of guys do this when firing up a ship in the morning when it’s cold to avoid the nuclear hot air then cold then hot ad infinitum and it seems to work quite well. I’ve never had a maintenance issue as a result. If you were worried you could achieve the same effect by leaving the temp selectors alone and turning the trim air switch off.

It depends on the serial number, but for certain serial numbers this is the applicable note in VOL II. I am not aware of any remedy:

"If all of the Temperature Selectors are placed to OFF, ALL ZONE TEMP LIGHTS, and L/R Pack lights will Illuminate. Flight crews are advised not to select the OFF position unless directed by a published procedure or checklist."

At my gig, from certain S/N and above it is recommended not to for the above reasons.... TBH never had such thing and if it happens all you have to do (as per QRH) is to select a cooler setting, no biggie. Must say im a big fan of it

Turning off the Trim Air wouldn't put the Packs to a default 65/75 temp, though, would it? Wouldn't it still look at the air temp sensor and try to go to full hot?