I’ve got a Mercedes W201 with two generic 10″ Chinese pusher fans mounted on the A/C condenser. They’re wired into the A/C system, so when the pressure rises above a certain threshold they kick on to keep the refrigerant temps down.

Problem: in summer traffic the fans just don’t move enough air. A/C performance drops and the engine cooling isn’t helped much either. That’s why I’m planning to swap them out for two 12″ SPAL high-performance fans. On paper the airflow (CFM) should be roughly 3× higher than what I’ve got now. Ideally this would also support the main radiator cooling.

I’ve got a few questions for those of you who’ve done similar upgrades:

1. Fitment:
2. My condenser is perfectly sized for 2×10″ fans.
3. 12″ fans will fit, but they’ll overhang slightly outside the condenser core area.
4. Is it still worth going 12″ for the extra airflow, or is “full coverage” more important?
5. Wiring / control:
6. Right now they’re tied to the A/C pressure switch.
7. I’d like to keep that, but also have them triggered by a coolant temp switch (thermoswitch) for engine cooling.
8. What’s the best way to wire this so either input (A/C or coolant temp) can trigger the fans? Relays + diodes?
9. Mounting distance:
10. Is there a recommended spacing between pusher fans and the condenser? Should they be mounted directly against it, or is a small gap preferred for airflow efficiency?

I’ll add some pics in the comments so you can see the current setup.