Select statement using case when inputting data in new column 'conversion failed'

I have a select statement where I am creating a new column called Program.

Select '' as Program

I want to have my case when statement put in this new column a string where the int from the UNIT_ID column is either 8191, 8192 or 8194.

CASE WHEN UNIT_ID = '8194' THEN 'Hospital'
WHEN UNIT_ID = '8192' THEN 'Clinic'
WHEN UNIT_ID = '8191' THEN 'Outpatient'
ELSE CONVERT(VARCHAR(35), UNIT_ID)
END AS PROGRAM,

My query starts off doing this:

WITH CDCLSVC_1 AS (
           SELECT CDCLSVC.*, CASE WHEN CDBILMOD.PROC_CODE = '' THEN

An later on this:

, CDBILMOD_1 AS (
           SELECT * FROM CDBILMOD
           )
, CDCLIENT_1 AS (
           SELECT * FROM CDCLIENT
           )

So far my query runs but does not input any data into my new Program column