Cabin altitute
 

On approach to Singapore today in an A320 as SLF.

Twice during the last 10 minutes or so of the flight there was a sudden blast of cold air from the AC and the cabin altitude rose quickly (rapid ear popping) for about thirty seconds each time. There was no obvious change in the flight - attitude, engine power, etc - at this point and the descent appeared, from a SLF perspective at least, quite normal apart from this.

I was just wondering what might have been going on here as none of this adds up for me. For example wouldn't increased airflow from the AC normally increase cabin pressure and thus reduce cabin altitude?

I've flown into Singapore hundreds of times and have never experienced this before although I don't often fly the A320 so don't know if this is a peculiarity of the type.

Sorry if this is the wrong place for this question. Just curious.

Thanks, Chris