When I swapped the dash out of my 89 for the 92, I found that the blower motor for the heat & air did not work on high. It works fine on the lower settings. I replaced every thing but the ac box under the hood. Is their a high pressure, low pressure relay like on the ac for the blower motor. If so where is it located.

 

its the relay for the blower motor, it is located just inboard of the blower motor. My 87 had this same problem.....my 88 don't tho, i am just waiting for it to happen seeing I have to keep the thing i high all the time to keep the Convert warm with the 180 stat and a top coming of the back...