My 68 with AC had two speeds on the three blower switch notches...low, medium and low. I've installed a new blower resister module on top of the air box and my 30 amp high-speed fuse is good and hooked to the alternator. Any ideas why I'm not getting a high speed?
The highest speed is direct current with no resistance. If the problem did not change when you changed the resistor it may be the blower motor itself. Jim
Most of the GM cars I mess with have a "high blower speed relay" on the firewall. There is a separately fused feed from the fuse block to this relay. If the fuse is blown, or if the relay is bad, when you put the switch in "high" you get all the blower resistance in series with the motor, resulting in the blower feeling like it's on "low." I think that's what you mean by "low, medium, and low."
The relay looks just like a horn relay, but it has different connections. On all but one car, it's been on the engine side of the firewall, mounted right next to the A/C box. (The exception was actually a 71 Chevy truck, where it was tucked up under the dash.)
If the relay is mounted under the hood (which it probably is), corrossion can also cause connection problems. Try spraying the terminals with WD-40 if they look questionable.
Good luck!
All articles which coruscate with resplendence are not necessarily auriferous.
Well, I went ahead and bought a new blower relay...it didn't change anything. I'll check my connections to the alternator. It soundn't be the dash switch should it?
Found the problem. The black ground wire that attaches to the base of the blower relay was bronken off at the cowl attaching point. Works great now; thanks for the help.
