I spent about a year with my car [91 diablo] before I managed to get the climate control working properly.

It is capable of blowing VERY cold, or very hot.

I would start by checking that there is enough gas in the system [careful not to overfill], and checking that the hi and lo side pressures look as they should. Check that the left side radiator fan is working to draw air over the air con condensor ?

With regard to the volume of air through the vents, it isn't massive, but if you get air coming through as you should at 8degrees centigrade, then not a problem. [At one stage when trying to get my system controlled properly I was able to get air coming through at 2 degrees centigrade]