heat does not get hot and also the selection stays on the ctr counsel but will

Most probably a vacuum leak between the engine's intake manifold and the heater control head, but could also be caused by a vacuum leak elsewhere on that same vacuum circuit, which includes the vacuum actuator on the front axle and the vacuum reservoir front right engine compartment area. The heat concern is due to either no coolant circulating through the heater core, or the "blend door" not responding to the heater control head because of low/no vacuum supply or, if electrically controlled, the blend door motor is inop. If your Chevy is equipped with electronic climate control, it's most likely the control head, itself