What was found
ON CLIMB-OUT HAD EQUIP COOLINNG O/HEAT LIGHT. AFTER SELECTING O/RIDE LIGHT EXTINGUISHED. SHORTLY AFTER HAD CABIN ALT AUTO 1 AND AUTO2 EICAS MSG WITH RISING CABIN ALTITUDE. SELECTED MANUAL AND REGAINED CONTROL OVER CABIN PRESS. CABIN ALT AUTO 2 CLEARED AND SELECTED BUT CABIN ALT CLIMBED AGAIN. BACK TO MANUAL AND RETURN TO ATL. REPLACED K 1008 RELAY GROUND CK NML REPLACED HEATEXCHANGER. SHUTOFF VALVE BITE CHECK ON LT CONTROLLER, REMOVED AND REPLACED CONTROLLER CKS GOOD.