02 air conditioning fans

Wiring diagram's definitely worth 1000 words for Gen 1.

It's the usual Prius arrangement, three relays, two fans, series for low speed, parallel for high speed.

The ECM gets a vote (if it thinks the engine needs more cooling). The A/C Amplifier gets a vote, if it thinks more cooling is needed for A/C. There's a separate single contact on the refrigerant pressure switch that gets its own separate vote. The water temperature switch in the inverter cooling loop gets a vote.

If no votes, the fans don't run. If the inverter temp is the only vote, both fans run low speed. Add any other vote and they both run high speed. If anybody else votes and the inverter temperature doesn't, looks like one fan runs high speed and the other is off.

Weird.

I think Gen 2 had a similar-but-not-the-same Rube Goldberg control arrangement mixing real switches and ECU outputs. It wasn't until Gen 3 they finally said "you know, we'll just drive all three relays from the ECM and use software to decide when to run the silly fans."

 

I would have mentioned that this was a Gen 2 forum and you own only Gen 1 and Gen 3 but after I saw the list of classic cars that you own, I was too awestruck. Amazing collection.

 

It's a subforum under Gen 2. Lots of people have trouble finding it.