manifold pressure

[Mathis]

I have a 2000 GT. On hard acceleration ( not full throttle) the a/c was changing from max air to defrost. I checked the manifold pressure and found it at 15 inches mercury at idle ( also saw that with no vacuum to the A/C control the system defaults to defrost.

15 inches seems very low. I checked for loose hoses and didn't find any. Since I have an extended warranty and the emmisssions warrantuy is still in affect I took it to the dealer ( also the transmission would not up shift to third till you let up on the gas).

Dealer says the transmission has a broken spring in the 2-3 accumulator.

But also says the 15 inches vacuum is normal for this car. The A/C guy is tearing everything apart.

I think the vacuum should be above 17 inches. I live in FL so hardly any elevation above seal level. The car is stock.

Caan some one confirm what the expected manifold vacuum should be.