Hello Harry,
I too added an auxiliary electric fan between my condenser and grill. I added a SPAL Model
VA11-AP7-/C-57S 12V fan turned on by a relay triggered by the AC clutch.
If you search SPAL VA11-AP7-/C-57S , you will get SPAL's web site and then search again the model number for all the details. I couldn't find the price on their site and don't remember what I paid. I bought mine from the mobile AC guy who came to my house to charge my AC. I probably paid too much but they are in the range of $100.00, I think.
The only problem I had installing mine was removing the grill and black grill screens to avoid removing the hood.
In the end, I removed the hood anyway to provide easier access to put the grill screen screws back.
It works great and my temperature also stays at about 80 or 81 degrees C even on a hot day here in Quebec.
Tom Kizer