What was found
TYS - A/C DIVERTED TO TYS WHILE EN ROUTE FROM ORD TO CHS WHEN THE NR 1 BLEED VALVE CLOSED. CREW DIVERTED TO TYS WHERE MAINTENANCE REMOVED AND REPLACED THE NR 1 ENGINE BLEED VALVE IAW EMB 145 AMM 36-11-05. OPS CHECK GOOD AND WAS RELEASED, A/C DEPARTED AND UPON TAXI OUT HAD A NR 1 BLEED VALVE CLOSED TO SHOW UP ON THE EICAS AGAIN, RETURN TO BLOCK WHERE MAINTENACE CHANGED NR 2 BLEED VALVE IAW EMB AMM 36-11-05, OPS CHECK GOOD AND CHANGED THE RELAY C7 IAW EMB AMM 20-13-00. OPS CHECK GOOD AND WAS RELEASED TO SERVICE. NO FURTHER ISSUES.