Toyota's various PTC Quick Heaters

#1

If you are looking for more details, kindly visit Hv Ptc.

Post by asavage » 3 years ago

My winter range is around 20-25% less than my summer range, mainly due to the high electrical energy consumption of this cabin heating arrangement.

My normal 60 mi./day commute is no problem, even when running the heater "full blast". But with the OEM heated seats, and appropriate clothing, I could run the cabin heat a lot lower than I have been -- other than getting cold feet. On certain trips, I sometimes want a bit more range cushion, so I've been looking at spot heating just my footwell.

Positive Temperature Coefficient (PTC) heaters are everywhere, and cheap. They have the unique property of getting just so hot, and no hotter. Initially, I was looking at the usual offerings on eBay, Amazon, etc.

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As it happens, my RAV4 EV already has a PTC heater installed. It's 840W capacity, three stage, and I guess it provides a bit of warmer air until the main water heater gets up to temp. I never noticed if it does much.

[Side note: to access/replace the PTC Heater in my vehicle, there is an enormous amount of work involved. The A/C Assy. has to be removed, partly because the PTC's integrated wire harness is sandwiched between it and the firewall. In order to remove the A/C Assy., you have to remove: front seats, carpet (partial), outside cowl, wiper motor, drain coolant, console, pretty much the entire dashboard, the horizontal dash mount tube, etc. It sounds awful to accomplish. Same labor to replace the water heater core.]

eBay has loads of used Toyota PTC heaters for cheap. I'm thinking of hanging one above my feet with a fan and some switchgear, for use when I'm trying to make a bit extra range in cold weather. Note that modern BEVs generally don't have to sweat range like my old rig; they're both more energy efficient (my old RAV4 EV is a bit more aerodynamic than a brick), have more efficient drivetrains, and have heat pumps that provide heat at moderate temps at a much lower energy usage.

The three most common Toyota PTC heaters are 330W, 495W, and 840W -- the latter is NLA. Below I summarize my best guess as to the applications in which each was installed. Bear in mind that the PTC Quick Heaters were not optioned in all markets nor all versions of a model. Notably, their are PTC heaters installed in Gas-engined vehicles and Cold Climate Diesel-engined vehicles, with two-stage heaters/wiring/relays, but Diesels in non-Cold Spec. got the three-stage units. Go figure.

Below, I document some info and circuit diagrams I've pulled from various sources. Some is redundant, esp. the multiple circuit diagrams, which all show pretty much the same circuit but in differing detail.

Toyota -
Denso -
12v

330W

- RAV4 (VIN starts with '2')
- RAV4 (some Limited/SE/Platinum)
- Matrix
- Corolla (with cold spec.?)

Toyota -
Denso -
12v

495W

Contact us to discuss your requirements of Ptc Car. Our experienced sales team can help you identify the options that best suit your needs.

- Corolla (some)
- Prius
- RAV4
RAV4 (2WD Outdoor Limited, Premium Limited)
Scion iM
- Lexus CT200h

Toyota - (NLA)
Denso -
12v

840W

(three connectors)

- RAV4
- RAV4 EV

Toyota 330W PTC Quick Heater

Toyota_PTC_330W_-_01b.jpg (982.98 KiB) Viewed times

Toyota 495W PTC Quick Heater

Toyota_PTC_495W_-_01b.png (1.74 MiB) Viewed times

Toyota 840W PTC Quick Heater

Toyota_PTC_840W_-_02b.jpg (264.38 KiB) Viewed times

Toyota 840W PTC Quick Heater, connectors view

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A couple more views of the later 495W unit:

Toyota 495W PTC Quick Heater

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Toyota 495W PTC Quick Heater: Denso part No.

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Toyota 495W PTC Quick Heater: connectors view

Toyota_PTC_495W_-_05b.png (1.2 MiB) Viewed times

Toyota 840W PTC Quick Heater: installation location in RAV4

Toyota_PTC_840W_-_01b.png (547.53 KiB) Viewed times

Toyota 840W PTC Quick Heater: Denso part No.

Toyota_PTC_840W_-_03b.jpg (121.54 KiB) Viewed times

Toyota 840W PTC Quick Heater: Connector terminals diagram (early w/(3) connectors)

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Toyota 495W PTC Quick Heater: Connector terminals diagram (late w/(2) connectors)

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Toyota 840W PTC Quick Heater: Early RAV4 relays location/information

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Typical Toyota PTC circuit, including both 2- and 3-stage PTC installations

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Typical Toyota PTC circuit, including both 2- and 3-stage PTC installations

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Typical Toyota PTC circuit

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Typical Toyota PTC circuit

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Typical Toyota PTC circuit

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PTC system description

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PTC system description

-_Toyota_RAV4_Aux_Heat_Circuit_04b.png (155.39 KiB) Viewed times

PTC Relays testing info

-_Toyota_RAV4_Aux_Heat_Circuit_07b.png (63.62 KiB) Viewed times

PTC Quick Heater location in A/C Assy.

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PTC Quick Heater location in A/C Assy., left side view

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I am looking for more driver's footwell heat. On old-school battery electric vehicles (BEVs), ones that don't utilize a heat pump -- as most modern BEVs do -- the electric heater is a significant energy consumer. My old Toyota RAV4 EV , which is based on the 3rd Generation RAV4 (-) , does not use a heat pump for cabin heating. Instead, it has a Denso water heater that runs off the HV (~400vdc) traction battery pack; it heats water, then an electric pump moves the hot water to a typical heater core, just like an ICE vehicle . The Toyota RAV4 EV of - was a rush job, the result of a collaboration with Tesla, who supplied the EV drivetrain and battery. It was designed to meet California ZEV compliance regs and didn't have a lot of engineeringMy winter range is around 20-25% less than my summer range, mainly due to the high electrical energy consumption of this cabin heating arrangement.My normal 60 mi./day commute is no problem, even when running the heater "full blast". But with the OEM heated seats, and appropriate clothing, I could run the cabin heat a lot lower than I have been -- other than getting cold feet. On certain trips, I sometimes want a bit more range cushion, so I've been looking at spot heating just my footwell.Positive Temperature Coefficient (PTC) heaters are everywhere, and cheap. They have the unique property of getting just so hot, and no hotter. Initially, I was looking at the usual offerings on eBay, Amazon, etc.I even ordered a couple. But, they are all so cheaply constructed that I began looking for something more robust. Toyota has been installing small PTC heaters in many of their vehicles since at least ; they're set up to provide a bit of heat when the ICE's coolant temp is low, particularly in cold climates or in versions of vehicles with diesel engines, which generate little heat when not loaded.As it happens, my RAV4 EV already has a PTC heater installed. It's 840W capacity, three stage, and I guess it provides a bit of warmer air until the main water heater gets up to temp. I never noticed if it does much.[Side note: to access/replace the PTC Heater in my vehicle, there is an enormous amount of work involved. The A/C Assy. has to be removed, partly because the PTC's integrated wire harness is sandwiched between it and the firewall. In order to remove the A/C Assy., you have to remove: front seats, carpet (partial), outside cowl, wiper motor, drain coolant, console, pretty much the entire dashboard, the horizontal dash mount tube, etc. It sounds awful to accomplish. Same labor to replace the water heater core.]eBay has loads of used Toyota PTC heaters for cheap. I'm thinking of hanging one above my feet with a fan and some switchgear, for use when I'm trying to make a bit extra range in cold weather. Note that modern BEVs generally don't have to sweat range like my old rig; they're both more energy efficient (my old RAV4 EV is a bit more aerodynamic than a brick), have more efficient drivetrains, and have heat pumps that provide heat at moderate temps at a much lower energy usage.The three most common Toyota PTC heaters are 330W, 495W, and 840W -- the latter is NLA. Below I summarize my best guess as to the applications in which each was installed. Bear in mind that the PTC Quick Heaters were not optioned in all markets nor all versions of a model. Notably, their are PTC heaters installed in Gas-engined vehicles and Cold Climate Diesel-engined vehicles, with two-stage heaters/wiring/relays, but Diesels in non-Cold Spec. got the three-stage units. Go figure.Below, I document some info and circuit diagrams I've pulled from various sources. Some is redundant, esp. the multiple circuit diagrams, which all show pretty much the same circuit but in differing detail.- RAV4 (VIN starts with '2')- RAV4 (some Limited/SE/Platinum)- Matrix- Corolla (with cold spec.?)- Corolla (some)- Prius- RAV RAV4 (2WD Outdoor Limited, Premium Limited) Scion iM- Lexus CT200h- RAV- RAV4 EVA couple more views of the later 495W unit:

Short answer is: It fails because of bad design. Is it worth it to replace with a new one or used? NO.

Long answer is: Nissan LEAF made between - used Eberspächer High-Voltage PTC heater, which is fitted under the 12V battery. As you probably already found out, this is most unreliable heater ever used by Nissan. Some of them failed in first few years of usage, some managed to survive till this day. But don't get excited if yours is still working. It will fail sooner or later. Why? Because of faulty design. First lets have a look why they fail. Look at these two pictures below and think what is wrong in them:

So if you looked carefully you probably noticed that almost all terminals that should be soldered to PCB stayed on PTC elements after I lifted PCB. Also color on them tells soldering had failed long time ago and now causing excessive resistance, heat, sparks, electric arcs or no contact at all. This puts a lot of pressure on electronics that eventually fails in quite spectacular way.

Look at the difference between these two terminals under the natural light. Left one was cleaned, and the right one is as it came from the heater:

And this is what happens when electronics can't handle it anymore. Look at them soot marks on PCB, aluminum and plastic casing caused by DC electric arc. Also if you look carefully you will be able to see aluminum melted on one corner. Not to mention exploded transistor. There were some spectacular fireworks going inside the heater

This failed heater is taken from LEAF with about 60k miles (~100k km) on clock. Sometimes the heater refused to work, this was the first symptom. Giving some random fault codes, but no fault light on a instrument cluster. Eventually it died completely, also blowing the 30A fuse in DC/DC junction block, which is a nightmare to replace. There were 5 or 6 fault codes telling there is no high voltage feed to the heater and each transistor inside, but strangely no fault light on instrument cluster again! After opening it, initial thought was that one or two PTC elements failed inside shorting the transistor, but after doing high voltage resistance test I found out this wasn't the case. So the only reason it fails like this in my opinion is failed soldering on PTC terminals. I have tried to replace faulty components and re-solder all terminals to make it usable again, but this is another story, which I will share a bit later.

So is it worth trying to replace it with a new one or a second hand one? Second hand one is a big NO! Because it's just a matter of time when it will fail again, as they all got same problem. For the new one, I am not sure if Eberspächer is aware of this problem and if they changed design. If they haven't sorted it and make exactly same heaters, then the answer is NO again. You will spend probably about couple thousands euros or pounds and you will be on the same gamble again. Not to mention all the difficulties removing DC/DC junction block to replace it or replace blown fuse inside it. Is there a cheap solution? Yes it is, but it's a bit dirty one I personally installed a Thermo Top diesel heater and have no regrets by doing this. I use lamp oil (kerosene) with it, which burns very clean, so not much bad emissions created. Also it uses very little of fuel. Will drop the post about it bit later. Another huge advantage of using diesel heater instead of PTC heater is, it won't affect the already small range of LEAF.

Please note that this post is just my opinion, I am not an expert and I can be wrong. So it's only up to you if you want to take my opinion as a truth or you better stick with Nissan dealership fairy tails

Why early Nissan LEAF PTC heaters fail and is it worth it to replace them.Short answer is: It fails because of bad design. Is it worth it to replace with a new one or used? NO.Long answer is: Nissan LEAF made between - used Eberspächer High-Voltage PTC heater, which is fitted under the 12V battery. As you probably already found out, this is most unreliable heater ever used by Nissan. Some of them failed in first few years of usage, some managed to survive till this day. But don't get excited if yours is still working. It will fail sooner or later. Why? Because of faulty design. First lets have a look why they fail. Look at these two pictures below and think what is wrong in them:So if you looked carefully you probably noticed that almost all terminals that should be soldered to PCB stayed on PTC elements after I lifted PCB. Also color on them tells soldering had failed long time ago and now causing excessive resistance, heat, sparks, electric arcs or no contact at all. This puts a lot of pressure on electronics that eventually fails in quite spectacular way.Look at the difference between these two terminals under the natural light. Left one was cleaned, and the right one is as it came from the heater:And this is what happens when electronics can't handle it anymore. Look at them soot marks on PCB, aluminum and plastic casing caused by DC electric arc. Also if you look carefully you will be able to see aluminum melted on one corner. Not to mention exploded transistor. There were some spectacular fireworks going inside the heaterThis failed heater is taken from LEAF with about 60k miles (~100k km) on clock. Sometimes the heater refused to work, this was the first symptom. Giving some random fault codes, but no fault light on a instrument cluster. Eventually it died completely, also blowing the 30A fuse in DC/DC junction block, which is a nightmare to replace. There were 5 or 6 fault codes telling there is no high voltage feed to the heater and each transistor inside, but strangely no fault light on instrument cluster again! After opening it, initial thought was that one or two PTC elements failed inside shorting the transistor, but after doing high voltage resistance test I found out this wasn't the case. So the only reason it fails like this in my opinion is failed soldering on PTC terminals. I have tried to replace faulty components and re-solder all terminals to make it usable again, but this is another story, which I will share a bit later.So is it worth trying to replace it with a new one or a second hand one? Second hand one is a big NO! Because it's just a matter of time when it will fail again, as they all got same problem. For the new one, I am not sure if Eberspächer is aware of this problem and if they changed design. If they haven't sorted it and make exactly same heaters, then the answer is NO again. You will spend probably about couple thousands euros or pounds and you will be on the same gamble again. Not to mention all the difficulties removing DC/DC junction block to replace it or replace blown fuse inside it. Is there a cheap solution? Yes it is, but it's a bit dirty oneI personally installed a Thermo Top diesel heater and have no regrets by doing this. I use lamp oil (kerosene) with it, which burns very clean, so not much bad emissions created. Also it uses very little of fuel. Will drop the post about it bit later. Another huge advantage of using diesel heater instead of PTC heater is, it won't affect the already small range of LEAF.Please note that this post is just my opinion, I am not an expert and I can be wrong. So it's only up to you if you want to take my opinion as a truth or you better stick with Nissan dealership fairy tails

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