Alright, I have a weird one and I can't find anything about it.
Haven't seen anything in FSM or AllData that stood out to me either.

Friend rebuilt his 3VZE top/bottom and it's overheating (wait for it) but it isn't overheating unless the fan blower motor is on and the blend door is set to cold- the AC switch can be off.

We can drive it forever and it will operate just fine... unless you turn the blower motor on and set the blend to the cold side- it will start climbing to overheat immediately.
You can get the RPMs going a bit in neutral to help cool it down but it will eventually head to red.

We did use an IR thermometer to check the upper & bypass hose, there is a temperature change, which suggests a mechanical issue. However, I'm open to the idea of an electrical issue if someone can point me in the right direction or to the correct diagram.


Thing we've tried/checked (multiple times to verify)

• Leakdown test was good
• HG combustion test was good
• Idle is set correctly, as is AC idle up
• Timing is correct, distributor/plugs/wires are new
  
• No air in the cooling system (used a vacuum filler)
• Thermostat is fine/new/oem - Tried it without as well
• Water pump is fine/new
• Fan clutch is fine/new (tried mine too, which we know is good)
• Fan blade is new (last one got chipped)
• Top & Bottom radiator/hoses get warm (new radiator)
  
• Removed compressor belt
• Condenser is clean, fins good
• Condenser fan operates as it should
• Heater does work so I don't believe the heater core is the issue.

I'm thinking of bypassing the heater core next, not sure why this would be it, but I'm throwing darts at a board now.

Any ideas are appreciated!

Any ideas?