Difficulty printing one particular query in MSSQL

I'm trying to construct a small query which will pull data from individual fields in a DB and print them in a human readable list format (it's what the operators are used to seeing). The code I have here is far from complete but It seems to me that it should work.

DECLARE @PSUCARD VARCHAR(20)
DECLARE @EQUIPMENT VARCHAR(50)
DECLARE @T1 VARCHAR
SET @PSUCARD = 'PSU-888'
SET @EQUIPMENT = '123_POUCH'

PRINT @PSUCARD + ':'
PRINT @EQUIPMENT
PRINT ''

IF (SELECT TEMPERATURE_MAIN FROM PSU WHERE PSU.PART_ID = @PSUCARD AND     PSU.OPERATION_RESOURCE_ID = @EQUIPMENT)IS NOT NULL  BEGIN
    SET @T1 = (SELECT TEMPERATURE_MAIN FROM PSU WHERE PSU.PART_ID = @PSUCARD AND PSU.OPERATION_RESOURCE_ID = @EQUIPMENT)
    PRINT 'Temperature: ' + @T1
    --(SELECT TEMPERATURE_MAIN FROM PSU WHERE PSU.PART_ID = @PSUCARD AND PSU.OPERATION_RESOURCE_ID = @EQUIPMENT)
END

If I execute the code as is, @T1 returns a * rather than a value. If I remove comments from the line below I am reassured that there is indeed a value there. I have other code very similar to this which works fine. Any ideas?

Also, I don't know if this helps in diagnosing the problem, but despite the temperature field in the DB being an INT, I get a conversion message if I try to treat @T1 an an INT.

via Chebli Mohamed