737 Equipment Cooling.

[Slasher]

Our new 737-300s are getting equipment cooling SUPPLY failures quite often, requiring switching to Alternate. This happens mainly on climb after departing an airport with high OAT. After about 30 min switching back to NORMAL can be done with no further problems. Never had any similar problem with the EXHAUST except for a real blower failure once.
Any of you blokes know what causes this exactly and what could be done to prevent it? And has Boeing produced any Tech Bulletin on the subject? Ta in advance.

Slash.

[MELman]

havent worked on them for a while, but one possibility is that you have a bad batch of sensors.Is the exhaust sensor the same
part # as the supply sensors?
Also the sensors have a tendency to get covered in fine dust and debris after a while so the airflow doesnt cool them sufficiently, but with new aircraft, I wouldnt expect that to manifest itself so soon.
hope that is of help
cheers
MELman