A320 pack overheat

[wheremi]

Why pack1(2) overheat when it’s closed. For example pack1 ‘’on’’,pack2 ‘’off’’, apu bleed ‘’on’’. In this configuration pack2 will overheat in 10-15 minuets. Why it is so ?

[J.L.Seagull]

Heat soak

Originally Posted by wheremi

Why pack1(2) overheat when it’s closed. For example pack1 ‘’on’’,pack2 ‘’off’’, apu bleed ‘’on’’. In this configuration pack2 will overheat in 10-15 minuets. Why it is so ?

The packs are located in a very tight compartment in the belly. The APU duct also runs through there

When pack 1 runs, it generates a lot of heat in the ambient area. The opposite pack when switched off, doesn't have any cold air exiting it's own turbine so it simply soaks up the heat from the surrounding area and triggers an overheat message.