No Ac And All Heat

[floridabound]

got a work truck, it's a 01 chevy silverado single climate with manual controls. all she does is blow hot air even with the ac on. the pressures are good in the ac system, the compressor cycles like she is suppose too, i changed the lower actuator which was easy any body got any ideas on where to next. thinking it's the upper one but don't know how to change it or where it is

[Carder09]

Not sure but It may have an air gate or baffle that separates the a/c coil from the heat coil, and it could be blocked, but had an old truck that the compressor would run but stop and repeat, turns out it had a low freon sensor and would start stop the compressor and it would only blow heat, added more freon and it worked