cabin air drops out when eccelerating whats the fix?

My 93 Dakota looses all the air in the cab when I excelerate. Any suggestions?

You didn't say which engine you have but most vehicles with the smaller engines kick the A/C compressor off on heavy acceleration to give a little extra power. I guess this is what you are referring to.

sorry about not putting a engine size in the first post:( It has a 318 Magnum in it. I think it is a vacuum problem. The air seems to go to the defrosters. I have replaced the vacuum check valve by the brake booster and it did not help. any suggestions would be nice! Thanks:)

If your softball (the black vacuum canister that is the size of softball) is hooked up and not leaking it has enough reserve to supply heater controls no matter how much engine vacuum varies. Your problem would have to be between the softball and your engine, maybe just a leaky vacuum hose, Rick

As long as the "softball" is not leaking the control valve and lines to the dash valve may be leaking or the checkvalve between the softball and intake fitting may not be sealing on accel

I've read about this before in a TSB from Dodge. If I remember correctly they want you to put a 1-way check valve in the vacuum line running through the firewall.