[pound41]

If you are talking about the plunger type solenoid that hooks on the carb with a bracket. I don't think that is the anti dieseling for the AC. I say that because I have 2 1971 Blazers. #1 doesn't have AC and it has the carb based solenoid but who knows.

Blazer #2 has AC. I will have to look and see if it has the carb based solenoid.
the fan switch and blower motor would only work on med.Which drives me crazy I checked all the grounds. Didn't fix the problem so I started replacing everything Heat and AC related. On my blazer down near the Cig lighter behind the dash it has a what I will describe as a relay mounted. The relay is very similar to the relay for the blower motor. The wires are different though. Anyway I found in my research that was a anti dieseling relay that was supposed to engage/disengage the clutch under load etc. This was a few years ago when I worked on it