Blows Hot air

hi All. Bought a 1986 944 this week with 104,000 miles on it. Great Car! But 2 quetions. The Ac blows real cold most of the time. Only thing is when you acccelarate, it blows blistering hot air out. Then when you level your speed, it blows back cold again. Im guessing the compressor cuts off during acceleration. But not sure. Can someone confirm? or do i need to fix something?
The other thing is sometimes at idle in drive ( automatic) the oil pressure light comes on. if you rev it a tad, goes out like normal. also if the car is on park, no problem. Does the idle need to be speed up a bit? Idles around 900. or should i have the oil pump looked at?

Thanks,

David