Well, there is one cheap fix.
Connect the low speed and high speed power circuits to the high speed wire at the fan.
If you do this, the fan will run on high speed if either circuit (high or low) turns on.
This is better for cooling the engine than having only the high speed circuit working. Also, the AC uses the low speed fan (mostly) but if it turns on the high speed fan the AC works better.
I'm using an inexpensive aftermarket rad fan on my 325. It only has one speed. It's been working well for about 4 years. I also removed the clutch fan at the same time.