Hello: I have been searching the archives but no answer. I have a 1987 with the Electronic Climate Control System. The fan will not go up on high it stops around setting six. I went to Napa and they gave me a module that is susposed to be the high fan relay. I looked on the board and see that it is located on the left side of the evap case. The only thing I see there is a small relay about one inch wide. The one Napa gave me is about three or four inches long and two high. I think I have the wrong part. Can anyone help me with this? Thanks in advance Wayne

 

Sounds like they gave you the wrong one. Take the old one with you or look up the part # at www.acdelco.com or www.napaautoparts.com (pick your poison - little difference between any GM Dealer and NAPA on this part - both seemingly charge about 100 Bucks). But first, verify that it's broken. Signal wire from the Dash or Programmer (depends on Year) is Brown or Tan. At 1 it should have 2.5 volts; at 10 - 6 volts. So put it on 10 and see if it has 6 volts. If it does, jumper the blower to the battery and see if it's any stronger. If not, the blower motor is bad or it's blowing air somewhere other than the vents - or the Evaporator is restricted (usually because it's been leaking and the foam filter on the inlet side is all clogged up) - or it's dropping volts at the Blower - check the connector for discolored wiring. You can also verify that if there is 6 volts on the Signal line that there is 12 volts on the output - Purple or Black/Red or whatever is hot at the Blower. If you don't have the correct input voltage then the input device is bad. Through '89, that's the Dash Controller. After that, the Dash sends the Blower Request over a serial data line to the Programmer and the Programmer sends the voltage signal to the Module. Best to troubleshoot through the CCM link with a bi-directional scanner as that will emulate the Controls. If it all works, you need a new Dash Controller - if it doesn't, a new Programmer.