1.gen 2012 Leaf ZE0 - No heat, no DTCs and heater fluid temperature sensor malfunction.

[skartun]

Hello!
Hope someone here can help me with some insight. Would be much appreciated.

Just bought a 1.gen 2012 ZE0 with no hot air from A/C. Its blowing cold air at full capacity.
After clearing DTCs with diagnostics no DTC are coming back regularly. From last scan P3193 was only one.

Newer seen any DTC related to PTC heater or DC/DC junction box (Ex: B27xx)

When I do a function test of the A/C with diagnostics tool the "heater fluid temperature sensor" jumps between 6*C (actual temperatur) and -40*C. When this jump occurs its also knocks out the "heater pump" and the "PTC consumption volt" to zero, and setts the "HV sply/block compl flag" to off (its on when the temperatur is 6*C). This jumping in temp occurs regularly every 5-20 seconds. Please see attached pictures.

Also the "PTC consumption volt" newer goes above 300W, even in longer periods of 6*C from the sensor..
"Energy consumption" in the dashboard showes about 300W. And a little more if I put on the A/C-function.
The hoses from the pump and PTC are cold. So no heat in the system..
Wouldn't the consumption be zero if the PTC of DC/DC fuse was blown?

It also seems the "heater pump" (waterpump next to the PTC) is not working. There is no vibration in the pump og hoses, and I can not hear any sound. But the functiontest of the A/C shows data that the pump is running ("Pump RPM (effektive)" is the same as "Pump RPM (direction)").

I have tried to replace the "heater temperatur sensor", but still same jumping in degrees and no heat.

Any suggestions of what i can try next?
Is it possible it could be the PTC or DC/DC junction box with no DTCs?!
Seems unlikely fram what I´ve seen online.
And would that cause the "heater fluid temperature sensor" to malfunction like this?

Thanks so much.

Actual temperatur: https://i.imgur.com/83Lxqpl.jpg
-40*C jump: https://i.imgur.com/P9yykS4.jpg

 

[GerryAZ]

Look for a loose connection or broken wire in the water temperature sensor circuit. -40 degrees C indicates a high resistance (or open) in the circuit since resistance of the sensor increases as temperature decreases. Since the system displays 6 C sometimes during the diagnostics, the sensor itself is probably OK if that is close to the actual water temperature. The controller probably needs to measure a steady temperature signal before it activates the heater and pump(s). Otherwise, it considers the unreliable temperature signal to indicate a problem and sets DTC's.

 

[skartun]

Thanks so much!! Thats sounds like a logical place to start.

Just to be clear. There is no DTCs on the car (Except P3193 which I think is not related).
Shouldn´t the jumping in temperatur create a DTC?

Has anyone tried a functiontest of the "heater fluid temperatur sensor"?
The value should be 100% stable?

 

[GerryAZ]

Resistance of sensor itself should be stable, but loose connection will cause unstable readings at HVAC controller.

 

[Bill238]

Which Foxwell tool are you using with your Leaf? I’ve got a similar issue and need to see those same values.

 

[skartun]

Foxwell 170P.

Thanks for the replies

I´ve measured the voltage in the connections to the temperature sensor. One is 0V and the other is 0,1V. Both stable...
Any suggestions where to start looking for loose connections or broken wire?

 

[Bill238]

You can do a continuity test on the wires from the high temp sensor to pins 30 and 37 on the connector for the ac auto amp. I’d swap out the sensor first though, given the variation you described. The sensor should give a variable response when in use. It ranges from 4.7V at -20C to 1.27V at 80C.

 

[skartun]

Already tried changing the sensor. Still same problem..

But I can start with the continuity test! Any next steps if that one is ok?

Is it the AC auto amp that supplies power to the temperature sensor?

Thanks!

 

[Bill238]

Yes, pin 37 is positive. You can download the service manual from here:

https://www.nicoclub.com/nissan-service-manuals
The one for the hvac will give you the pinouts.

 

[Bill238]

Let me know how your continuity tests go. I’m seeing similar results with a Foxwell, but my heater pump shows no numbers at all, which should throw a DTC, but isn’t. I might replace that and see.

 

[skartun]

You are also seeing a fluctuation between -40*C and actual temperatur with Foxwell?
Is it your heater pump (that is circulating fluid through PTC) or your PTC that are showing no numbers?

I´ll try to do the continuity test as fast as possible and report back.

 

[TobyHolland]

I often find on the Wet PTC heater failure cars, that they can blow the 30A fuse inside the DC/DC unit at the same time.
The fuse is available from electrical suppliers, and EVsEnhanced, it's a hugely labour intensive job, but worthwhile if you're looking to restore full functionality with maybe a good used wet PTC.....

 

[Bill238]

You are also seeing a fluctuation between -40*C and actual temperatur with Foxwell?
Is it your heater pump (that is circulating fluid through PTC) or your PTC that are showing no numbers?

I´ll try to do the continuity test as fast as possible and report back.

I am seeing the almost the exact same fluctuation. I was able to get my pump readings and it’s operating properly. My PTC only shows 50W draw, but I haven’t let it run long to see if that changes.

 

[Bill238]

I often find on the Wet PTC heater failure cars, that they can blow the 30A fuse inside the DC/DC unit at the same time.
The fuse is available from electrical suppliers, and EVsEnhanced, it's a hugely labour intensive job, but worthwhile if you're looking to restore full functionality with maybe a good used wet PTC.....

Do you get a DTC or set of them when the fuse is blown? I’m not getting any so I was thinking it might be a erroneous sensor signal rather than an outright sensor failure.

 

[TobyHolland]

Do you get a DTC or set of them when the fuse is blown? I’m not getting any so I was thinking it might be a erroneous sensor signal rather than an outright sensor failure.

Yes, I had DTCs -it was 5 years ago now, so can't trace the records from back then

 

[Bill238]

Yes, I had DTCs -it was 5 years ago now, so can't trace the records from back then

No worries! It helps a lot just to know that it did. Gives me some hope I won’t have to deal with the DC/ DC converter.

 

[coolerguy]

Could easily be a variant of the issue I had in https://mynissanleaf.com/threads/b2794-hvac-heater-pump-hac-114-no-heat-2012-leaf-resolved.33820/, just throwing different error codes. Replacing the pump is a relatively low-cost piece of troubleshooting

 

[skartun]

Could easily be a variant of the issue I had in https://mynissanleaf.com/threads/b2794-hvac-heater-pump-hac-114-no-heat-2012-leaf-resolved.33820/, just throwing different error codes. Replacing the pump is a relatively low-cost piece of troubleshooting

Hmm.. Its really wired that I dont have any DTC's....

Do you remember how many watts your PTC was using when this issue was going on?
Me and @Bill238 as have a PTC thats using 50-300W...

 

[skartun]

Just repeated the voltage measurement on the heater fluid temperature sensor harness.
I must have measured wrong the last time. Now I get 4,95V on terminal 2 (Says in the manual it should be on terminal 1?!).

I don't have the equipment to measure the continuity from A/C auto amp to the heater fluid temperature sensor..
But I recon that isn't as important now that i have measured 4,95V ?!

I also tested the A/C relay (R6) and checked fuse #32 (A/C). They are both working..

Still doesn't feel any vibrations in the water pump closest to the PTC heater (the one under the battery). I've compared to the one on the right side thats easy accessible. Dont think its any movement in the pump, but hard to be 100% sure.

Still no DTC and same problems as described in the first post..

Any suggestions of what to try next?
Thanks!!

 

[Bill238]

Just repeated the voltage measurement on the heater fluid temperature sensor harness.
I must have measured wrong the last time. Now I get 4,95V on terminal 2 (Says in the manual it should be on terminal 1?!).

I don't have the equipment to measure the continuity from A/C auto amp to the heater fluid temperature sensor..
But I recon that isn't as important now that i have measured 4,95V ?!

I also tested the A/C relay (R6) and checked fuse #32 (A/C). They are both working..

Still doesn't feel any vibrations in the water pump closest to the PTC heater (the one under the battery). I've compared to the one on the right side thats easy accessible. Dont think its any movement in the pump, but hard to be 100% sure.

Still no DTC and same problems as described in the first post..

Any suggestions of what to try next?
Thanks!!

Yes, the Foxwell unit you have will show the pump activation and real time rpms, which is how I eliminated it as the issue on mine. I’m still going to check the continuity on the sensor. I saw on another post that if the sensor reads anything below -20F, it shuts the heater down to protect the pumps, etc from liquid freezing. That makes sense as there are no sensor resistance values below that temp. I’m still wondering about those -40F readings we both saw. Even if the sensor was throwing that valve intermittently, it would still shut the system down or at least cycle it. I’ll post when I check the continuity on mine.