There are times when everything appears to be operating according to all specifications, yet, insufficient cooling is the
Heat strips energizing with cooling-Check the heat relay in the air handler and see if there is 24 volts being applied to the holding coil.
The resistive heaters would counteract the cooling effect. Sometimes the contacts of a heat relay weld in the closed position, causing this. If 24 volts are found at the relay when the thermostat mode is in cooling, you must check the system circuitry. Disconnecting for the summer is alright; however, you will have to isolate the problem sooner or later. The source should be found in the evaporator section. It is either receiving its voltage from the thermostat or the defrost device in the condensing unit, if it is a heat pump. Sub-bases are sometimes the blame. They distort on an uneven wall surface causing them to crack or short circuit.