besides mono valve what causes 300 td to blow only hot air ???????
 

I change the mono valve with a replacement insert . Still only hot air. Installed a rebuilt climate control same thing . What do I do next?

Hot Air
 

Is the compressor engaging? With the hood open have someone turn on the
A.C. (the compressor will audibly engage) If not check the refrigerant (may be
low enough to prevent the compressor from starting)
'Find the electromagnetic clutch's power wire and put 12 volts to it ,If no
engagement the clutch may be bad.