Ac/heat Only When Accelerates

I Have A 95 4x Runner With 150k Miles. The Ac And Heat Only Cool And Heat When The Vehicle Is Accelreating. When Idling The Blower Just Blows In Outdoor Air (hot In Summer, Cold In Winter). Is This A Compressor Issue? Anyone Know What It Would Cost To Be Repaired? Abot To Sell And And Not Sure If I Should Repair Or Take Cost Of Repair Off Asking Price?
Thanks

Anything that affects both heating and a/c is not strictly a compressor problem. Sounds more like a ventilation problem in the ducting or valving. Impossible for me to judge. Since it only operates under acceleration (numerically low intake manifold vacuum), it is likely to be a vacuum-actuated valve. The actual problem may be a loose or cracked vacuum hose or possibly a mis-routed vacuum hose.

I would take it to a dealer and have them give me an estimate. If possible, get it fixed. It is a much easier sell if the vehicle has no outstanding problems than if there is an issue and the buyer needs to spend the time to get it fixed. People want to buy a trouble-free car.