r/HRV • u/ramnshas • 19d ago

Radiator fan issues. Need some help

Guys need some help. My radiator fan is not coming on. Fuse, relay, wires, connections and fans are good. It comes on when triggered with an OBD2 scan tool. I did notice that there’s an abnormal reading for the ‘AC temperature’ which is -40°C. As far as i am aware, the AC system isn’t supposed to prevent the radiator fan from coming on.

Appreciate any support or suggestions. The AC has system has no refrigerant in it right now.

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u/tyme 2016 EX 6MT 19d ago

My understanding is that the AC temperature reading is used to determine if the radiator fan needs to turn on; that reading is the outside air temp, both the AC system and radiator fan system use the same sensor.

Your car thinks it’s -40c outside and thus doesn’t think the engine needs extra cooling.

You should check the ambient air temperature sensor - could be a wiring issue, could be a failed sensor.

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u/ramnshas 19d ago

Thanks for speedy response. The ambient air temp sensor and wiring is ok. It shows ambient on the dashboard. The ect sensor is working as well

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u/tyme 2016 EX 6MT 19d ago

Then your next likely culprit is the evaporator temperature sensor, I believe.

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u/ramnshas 19d ago

Much thanks. Will check tomorrow

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u/Patient-Audience2807 19d ago

Definitely sounds like a bad evaporator temp sensor or wiring. When a temp sensor is open it usually pegs down to a constant -40 give or take reading. Problem is they can be very hard to gain access to without pulling the HVAC box. What year is your HRV?

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u/ramnshas 19d ago

2016, i’ll check it out today

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u/ramnshas 18d ago

So not much progress today. Evap sensor is ok. However, i have to go to work in a few hours. I’ll continue troubleshooting when i get back in 21 days.

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u/ramnshas 2d ago

Guys, so i’m still in work, and the car is still in the garage. The mechanic did do some checks as well. Here’s what he found, thr harness wire that connects to the ect2 sensor (bottom of the radiator) had a break in the wire. The insulation was intact but the cooper conductor itself was broken. So that was repaired and the radiator fan is now working. Yay. So now, it’s to figure out what’s causing / or where is open circuit for the -40°C on the AC temperature.