ALL POSTS - Heater Failed - Service Bulletin TSB 0111-14

[bdunst]

Can anybody contribute DIY information on replacing the heater with the later/more reliable Denso unit? The fuse replacement is documented, but are people using the early Leaf heaters as a replacement for the one used in the RAV4 EV?

The Toyota version has an integrated HV harness:

View attachment 13

View attachment 14

The early Leaf unit has a connector on the unit instead:

View attachment 15


I can see buying a Leaf unit and a bit of a Leaf's heater harness, then splicing the Leaf harness to the RAV4 EV's heater's harness . . .

View attachment 16

. . . which is straighforward enough, but is there a better solution?

I have been looking at this option as well. to take your existing wiring harness and use on the Leaf looks pretty easy based on Tony Williams video showing the heater opened up - just a couple wires inside that harness. unless I am missing something.

The only issue I have on these leaf heaters is they are as old as the rav heaters or older. I cant find teh newer denso heaters at amy price that would be a benefit over the stock rav unit.

I have been looking thru the posts about dealing withe coolant when replacing the heater. If anyone can point me somewhere or explain what do - that would be very helpful

 

[asavage]

I have been looking thru the posts about dealing withe coolant when replacing the heater. If anyone can point me somewhere or explain what do - that would be very helpful

I removed the cabin heater and its reservoir as part of the OBC fuses replacement process in Apr2023, and when I reinstalled it, I merely refilled the reservoir and ran the heater for a couple of minutes, then topped it off again. No air purge procedure necessary.

 

[bdunst]

I removed the cabin heater and its reservoir as part of the OBC fuses replacement process in Apr2023, and when I reinstalled it, I merely refilled the reservoir and ran the heater for a couple of minutes, then topped it off again. No air purge procedure necessary.

I purchased a new Leaf heater - its 5K vs 6K Rav unit. It was about half the cost of a new rav unit.
I am hopeful to make it work - but first I would like to do the test you mentioned on the existing heater - and I would like to figure out if the dc-dc is out. Are there any symptoms of the dc-dc converter being out?
I have the parts to put a cable together for Vlad to do a diagnostic - I hope to be able to get this car somewhere I don't have to worry about moving it for a while - hopefully next week.

 

[asavage]

. . . but first I would like to do the test you mentioned on the existing heater - and I would like to figure out if the dc-dc is out.

See steps 5 through 8 of the TSB that I posted upthread.

Steps 5-6 tests the heater (note: polarity sensitive)
Steps 7-8 tests the cabin heater fuse located inside the DC-DC Converter

 

[alflash]

I purchased a new Leaf heater - its 5K vs 6K Rav unit. It was about half the cost of a new rav unit.
I am hopeful to make it work - but first I would like to do the test you mentioned on the existing heater - and I would like to figure out if the dc-dc is out. Are there any symptoms of the dc-dc converter being out?
I have the parts to put a cable together for Vlad to do a diagnostic - I hope to be able to get this car somewhere I don't have to worry about moving it for a while - hopefully next week.

Before installing a similar-looking heater from a car of another brand, I made sure to check the correspondence of the power control signals of both devices


Have you tried to check the internal components of the interior heater?

https://alflash.com.ua/2019/to_rav4ev/cabin_heater1.jpg

https://alflash.com.ua/2019/to_rav4ev/cabin_heater_fr.jpg

https://alflash.com.ua/2019/to_rav4ev/cabin_heater2.jpg
https://alflash.com.ua/2019/to_rav4ev/COOLANT_ REPLACEMENT.pdf
p.s. Results of this checking?



Cabin Heater Fuse is good?

 

[ph2]

Good Evening All! The heater on my Rav died a couple of weeks ago on the way to work. Found one on Ebay that came from a Ford Focus. All of the connectors are different but the wiring is the same. The heater failed open so it didn't take the fuses with it, thankfully! A working heater has continuity in one direction of just over 200k ohms and about 1.8M ohms (when working). You can use the 200k ohm resistance to make sure you pair up the + and - wires correctly using an ohmmeter.Tightly-wound heavy duty foil will ensure continuity of the shielding. The interconnect system uses the shielding so the foil and overlap of the shielding is critical, and don't forget to disconnect the 12V battery. Finished it up with marine rated heat shrink. Also of note this heater unit is 6.3kW, which uses about 1 more amp, no issues so far but it may be cutting it close on a really cold morning if too much is being pulled on the 12v side, battery heater and cabin heater collectively.

 

[ph2]

One other note, with car in ACC mode, cabin temp set to high and not charging, the cabin heater pump will run without the heater being powered and purge most of the air. Not a good idea to start the heater up with no water in it, even for just a few seconds. After a minute or two, run like normal.

 

[bdunst]

I am curious what people think about using the Nissan 5Kw vs Rav 6Kw vs Ford 6.3 Kw?

 

[alflash]

Thank you for this description of yours.
If this is your photo* of testing the resistance of a faulty heater, then what are the results of measuring this resistance of this heater?

* https://alflash.com.ua/2019/to_rav4ev/ph2-2.jpg

 

[ph2]

Thank you for this description of yours.
If this is your photo* of testing the resistance of a faulty heater, then what are the results of measuring this resistance of this heater?

* https://alflash.com.ua/2019/to_rav4ev/ph2-2.jpg

The wire that I cut shorter on the right (with the positive red probe) and the longer wire contacted by the negative probe, results in the resistance just over 215k ohms. If reversed, there was no continuity. I marked the wires to match that of the probes with 215k ohms.
The same 215k ohms for the new heater, but the reverse resistance was 1.8M ohms. I marked wires to match the probes with 200k ohms. Match up the wires and splice.

 

[ph2]

I am curious what people think about using the Nissan 5Kw vs Rav 6Kw vs Ford 6.3 Kw?

The vehicle doesn’t so much care about the increased heater load itself… the only thing that may be an issue is the slight increase in current over stock for the 6.3kW heater.

Can't say for sure, but I posit that the DC converter pulls back the load by changing the duty cycle of the heater when it detects a high HVDC bus load. I say this because the stock heater and battery heater running concurrently could pull more than the fuse rating of 40 amps, especially with a low HV battery SOC and high 12v load.

The 5kW heater would give you more headroom and less demand on the HV bus, but would take longer to heat the loop up and put out fewer BTU. As a result the absolute minimum outside temperature where the heater could keep the car comfortable would be higher vs the other two. BTU ratings are 17k vs. 20.4k vs. 21.5k BTU respectively.

 

[bdunst]

The vehicle doesn’t so much care about the increased heater load itself… the only thing that may be an issue is the slight increase in current over stock for the 6.3kW heater.

Can't say for sure, but I posit that the DC converter pulls back the load by changing the duty cycle of the heater when it detects a high HVDC bus load. I say this because the stock heater and battery heater running concurrently could pull more than the fuse rating of 40 amps, especially with a low HV battery SOC and high 12v load.

The 5kW heater would give you more headroom and less demand on the HV bus, but would take longer to heat the loop up and put out fewer BTU. As a result the absolute minimum outside temperature where the heater could keep the car comfortable would be higher vs the other two. BTU ratings are 17k vs. 20.4k vs. 21.5k BTU respectively.

Thanks - one more question - did you have to disconnect jdemo or just move it aside? and did you disconnect the HV battery for this work?

 

[alflash]

Thanks for answering my questions.
I wonder what the external signs of a malfunction in the heater cabins were. Very weak interior heating only with Quick Heater Assembly?

Can't say for sure, but I posit that the DC converter pulls back the load by changing the duty cycle of the heater when it detects a high HVDC bus load. I say this because the stock heater and battery heater running concurrently could pull more than the fuse rating of 40 amps, especially with a low HV battery SOC and high 12v load.

Note.
The cabin heater and battery heater are powered through different fuses (40A vs. 20A *).
In addition, they have completely different and independent heating control circuits and principles.

https://alflash.com.ua/2019/to_rav4ev/heaters_on_data.jpg
* https://alflash.com.ua/2019/to_rav4ev/fuse_20a.jpg

One of the possible causes of a malfunctioning cabin heater.

https://alflash.com.ua/2019/to_rav4ev/igbt_check.jpg

 

[alflash]

... and did you disconnect the HV battery for this work?

Please, take a look https://alflash.com.ua/2019/to_rav4ev/__PRECAUTION2.pdf

 

[ph2]

Thanks - one more question - did you have to disconnect jdemo or just move it aside? and did you disconnect the HV battery for this work?

First step is always disconnect the 12v battery, wait for the 12v side to discharge and then remove the HV battery disconnect under the passenger seat before working on the HV side.
I took the jdemo junction box off (12 screws and 2 connectors on right side), folded to the left and then removed the angle bracket (4 screws) on the right side. Once those were clear, the hose clamps were easy to get to and the heater lifted out with minimal effort after disconnecting it’s two connectors. IIRC the screws are 5mm hex on the jdemo and 10mm nuts on the heater.

 

[ph2]

Thanks for answering my questions.
I wonder what the external signs of a malfunction in the heater cabins were. Very weak interior heating only with Quick Heater Assembly?



Note.
The cabin heater and battery heater are powered through different fuses (40A vs. 20A *).
In addition, they have completely different and independent heating control circuits and principles.

https://alflash.com.ua/2019/to_rav4ev/heaters_on_data.jpg
* https://alflash.com.ua/2019/to_rav4ev/fuse_20a.jpg

One of the possible causes of a malfunctioning cabin heater.

https://alflash.com.ua/2019/to_rav4ev/igbt_check.jpg

Thanks for the note… didn’t have the displeasure of needing to open up the dc converter this time around. If that’s the case then there should be no concern over the extra 300 watts burning the fuses.
I did notice the smell of burning electronics (or a bad cigar) a few times leading up to the failure but never found anything obvious. The heater was a slow fail… it worked fine the first 15 minutes of my commute and then slowly faded. It was then I put the two together and left the climate system off until I replaced the heater.

 

[alflash]

...
I did notice the smell of burning electronics (or a bad cigar) a few times leading up to the failure but never found anything obvious. ...

Escuse me for the additional comments, but to this your note I will prompt the comment that the Cabin Heater and DC/DC Converter (in which the cabin heater fuse is located) are water-cooled, completely sealed assemblies and cannot be a source of odor from burning electronics.
Therefore, it is not clear what could have caused the smell before replacing the heater.

This video might be interesting

 

[asavage]

I did notice the smell of burning electronics (or a bad cigar) a few times leading up to the failure but never found anything obvious.

At the first use of heat at the end of Summer, I too smell an odd odor and I suspect it's dust on the "Quick Heater" (PTC heater) that has accumulated during months of disuse. See this post for details.

 

[ph2]

Escuse me for the additional comments, but to this your note I will prompt the comment that the Cabin Heater and DC/DC Converter (in which the cabin heater fuse is located) are water-cooled, completely sealed assemblies and cannot be a source of odor from burning electronics.
Therefore, it is not clear what could have caused the smell before replacing the heater.

This video might be interesting

Water-cooled yes… completely sealed not exactly. Like most ‘enclosed’ systems on a vehicle they are rated against ingress but are vented. I had suspected the small button on top of the heater was such a vent, but disassembled today to confirm.

Upon opening, I can confirm with 100% certainty the smell I detected matches that inside the heater. Also, the button is a vent that equalizes the heater case to the atmosphere… I pushed through the hydrophobic media to confirm it’s a clear opening.

The odor is no longer present with the new heater installed and no other work has been completed.

 

[alflash]

Water-cooled yes… completely sealed not exactly. Like most ‘enclosed’ systems on a vehicle they are rated against ingress but are vented. I had suspected the small button on top of the heater was such a vent, but disassembled today to confirm. View attachment 71

Upon opening, I can confirm with 100% certainty the smell I detected matches that inside the heater. Also, the button is a vent that equalizes the heater case to the atmosphere… I pushed through the hydrophobic media to confirm it’s a clear opening.
View attachment 72View attachment 73
The odor is no longer present with the new heater installed and no other work has been completed.

Thanks for clarification!