87 944 AC issues, cold then hot
 

I have an 87 944 NA and the AC system is NEW! New compressor, drier, converted to R134. It blows cold for 5 minutes and then goes hot as balls. I have already replaced heater control valve. I saw somewhere the temp switch may be bad. Where is the temp switch and how do I check it? Any other tips? Spent a lot of cash on AC for it to blow hot!