Nissan Repair: loss of power brakes when A/C is turned on, nissan sentra, power brakes

Question
What would cause my car to lose it's power brakes intermittantly when the A/C is running?  The car is a 1995 Nissan Sentra GXE,1.4L,Auto. The brakes act as if the engine was off; you must press very hard to stop.  I did the Power Booster test and it is fine.  I replaced the in line vacuum check valve.  I have narrowed it down to the A/C running.  The air recirculate button can be on or off it had no effect.  Any ideas?

Answer
Allan,

There should be no connection between the two.  If the power booster works it should be good with or without airconditioning.  

Is the pedal hard when you say the brakes are not working under power?  Or, is it the compressor is making the engine continue to spool due to the idle solenoid not letting off the throttle?  I would check this.  I know the idle goes up when the air is on and if this is the case the brakes might seem to be less effective.  Check this out and email me back.