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Gen 1 Leaf Heater pump fault - B2794

Posted: Tue Jun 05, 2018 3:46 am
by DanNZ2
Hi all. First post for me. I'm in New Zealand.

I have a 2012 gen 1 Leaf. Have owned for just over a year - equivalent of 15000 miles on the clock.

The car's heater has just stopped working - cold air only. I have the Leafspy app and an OBD2 reader. The fault I get is "B2794 0009 Heater Pump HAC-114"

I have found a PDF workshop manual for the car and this fault is either caused by a stuck heater pump, an element temperature malfunction or an over current malfunction. The manual goes on to talk about doing a Self Diagnostic Result, presumably using a Nissan diagnostic computer, I think this is just to confirm the code is present, it then goes on to talk about doing a "HAC-30 consult function" which of course I cannot do, however it looks like this is for "intermittent faults". This is definitely not an intermittent fault! The manual then has fairly detailed instructions for replacing the heater pump.

Importantly the PTC heater does NOT seem to be faulty. To be clear - I'm talking about the heater pump on gen 1 cars, not the "heatpump"
heater on gen 2s.

I have pictures of the error code screen from Leafspy and also from the manual I've found, but I can't seem to easily post them!

Has anyone ever had this fault? Has anyone had experience replacing the heater pump?

Re: Gen 1 Leaf Heater pump fault - B2794

Posted: Tue Jun 05, 2018 12:13 pm
by 91040
Check this thread: 2011 Leaf SL : Heater Not Heating

Re: Gen 1 Leaf Heater pump fault - B2794

Posted: Tue Jun 05, 2018 7:57 pm
by GerryAZ
Since the little circulating pump or the temperature sensor are much cheaper than the PTC heater, I would try troubleshooting the pump and sensor in detail. You could disconnect the pump and measure the resistance between terminals. You could also try running the pump from a 12-volt source directly. If those tests are not conclusive, you could remove it and see if the impeller turns freely. The temperature sensor is in the liquid lines. Its resistance varies with temperature so you could unplug the wire harness connector, measure the resistance, and compare the resistance to the graph of resistance vs. temperature in the service manual.