I have a 1989 F-150 that is currently having a A/C cooling problem. About half of the evaporator gets cool when the A/C is on recirc and the blower is unplugged. My F-150 book trouble shooting charts suggests that there is a restriction on the suction side. I have had history with the orifice gettiing clogged with a gray colored viscous goo. Last time i had this problem was just after swithcing from R-12 to R-134. I assumed that the freon type switch caused this problem so I replaced the comp, drier, and all of the hoses. The evaporator and the condensor were both flushed. Any suggestions where this gray colored goo is coming from?

 

The goo is probably incompatible oils that have mixed.


Steve