PTC cabin heater repair

Hello,

I have 2017 Model X. About a week ago I smelled burning electronics inside the cabin and almost immediately after that heard a fuse pop. Then it was only cool air coming out of the vents. I knew it was the heater.

I took the PTC heater off and took it apart. There are 6 IGBT-modules controlling the actual heater elements. Heater itself consists of 9 different heating elements. They are controlled as follows; 3 elements have individual IGBT and 6 other elements are paired to one IGBT per two elements. I guess they are shuffled and they are not fully on all the time.

I measured resistance between those 9 elements. Measurements were between 1000 and 1500 ohms. Broken element had more than 33 000 ohm resistance. Also its controlling IGBT was shorted (drain to source). I desoldered the element from control board before measuring. It is relatively easy to measure resistance even if element is still attached to control board.

I desoldered all the IGBTs from control circuit and replaced all but shorted one with new ones. Put the whole element back in the car and replaced hv-fuse in front high voltage junction box. Heater came back alive and did not blow fuse again. One out of nine elements is not providing me heat but it is way better than driving without heat at all. Here in Finland its below zero celcius right now so heat is more than welcome.

Ranger quoted me 1300€+ for replacing the elements + fuse. Replacement IGBTs were 70€ including shipping fees. Replacement fuse was about 50€ from Tesla. I could have sourced it for about 10€ but I was in hurry to get it.

I will post some pictures with explanations soon.

 

[Retkimora]

Heater element removed from its hiding place. Plastic cover also removed.

Six IGBTs controlling 9 heater connections. Big terminal posts for high voltage positive and negative. One IGBT has external thermal sensor on top of it. Second IGBT from the left was shorted (drain-to-source).

Closeup of the control board. Notice how 9 elements are connected to IGBTs; 3 of element connections go to single IGBT and rest are in pairs. 1 IGBT controls two parallel heater connections. Two separate connections near capacitors are common. You can measure resistance of elements between common and any element. Notice parallel elements will show about half resistance only.

 

[brainhouston]

Do u have a photo of fuse location?

 

[Retkimora]

Heater element desoldered from PCB. It was major pain with cheapo 100W soldering iron and solder sucker.
This is not needed if you are about to replace IGBT modules. I just wanted to see how its all connected. About 1000 to 1500 ohms between elements at +21C. Broken element had 33kohm resistance.

Fuse inside the front high voltage junction box (FHVJB). SIBA-brand 40A fuse, type 5012434 (14x51mm). About 60€ from Tesla, 11€ online (cheapest I could find).

FHVJB location. It took a lot of effort to get there. Lost at least one 10mm socket and some nuts between firewall and front motor. But it is doable; ranger won't drop the hv battery and would have done it about this way I guess. Cover can be removed and fuse replaced without getting the actual box or wires removed. It is hard though.

 

[Retkimora]

Do u have a photo of fuse location?

No, sorry about that. There are two similar sized fuses inside the box and its the leftmost one. Easily identified with multimeter too.

 

[Retkimora]

Original IGBT is AUIRG4PH50S. It seems obsolete. I replaced mine with IKW40T120. Bought them from Mouser.com for about 9€ each. Used only 5 as I left broken element unconnected. Gate diodes were fine and I'd think the driver circuit still works.

I still need to do more testing on this repair but initially it seems to work. I don't have clear idea why PTC broke in the first place but guess it started getting high resistance at some point and burned itself during the process. It is irrepairable. IGBT failed at the same time. I already told the local ranger that he is welcome to replace the heater if my repair fails at any time.

 

[Jazu]

Dear Mr.Mora, RetkiMora. Would you say that 28kohm from external connectors indicates broken ptc? I bought a used rear PTC, but the value seems high and would not like to have the trouble of changing it if it is already broken.. I did not open it yet so I perhaps could complain about the resistance and selling broken part to the seller -> by opening "I have broken it"..

 

[brainhouston]

I don't think you can get correct (useful) reading from external connector...

 

[Jazu]

I don't think you can get correct (useful) reading from external connector...

Ok, thanks! I opened the cover and measured against common. 1k, 2.4k, 1k, 1,5k and 0.6kohm's so I would say the elements are ok.

 

[latifimr]

Thanks for sharing this guide. My 2018 Model 3 PTC heater stopped working. The boards are different but the same logic worked. I checked the resistance of all the elements and one was different from the others. I disconnected that element from the board and put everything back together. To my surprise, it just worked. Heat working again and error msgs gone.

For anyone else facing a Model 3 PTC heater problem, I’ve marked the location of the element to board connection where you can measure resistance. These are the same tabs I pulled out to disconnect the problem element.

 

[Cris disrupts]

No, sorry about that. There are two similar sized fuses inside the box and its the leftmost one. Easily identified with multimeter too.

This is the fuse box for my Tesla Model X 2017

 

[brainhouston]

This is the fuse box for my Tesla Model X 2017

Nice pics!
What was the issue n solution?

 

[Cris disrupts]

Original IGBT is AUIRG4PH50S. It seems obsolete. I replaced mine with IKW40T120. Bought them from Mouser.com for about 9€ each. Used only 5 as I left broken element unconnected. Gate diodes were fine and I'd think the driver circuit still works.

I still need to do more testing on this repair but initially it seems to work. I don't have clear idea why PTC broke in the first place but guess it started getting high resistance at some point and burned itself during the process. It is irrepairable. IGBT failed at the same time. I already told the local ranger that he is welcome to replace the heater if my repair fails at any time.

I dont understand ("It is irrepairable") if you manage to repair the heater presented in the pictures above...or you purchased a new heater.

Please clarify what it is irrepairable!

I have the same issue, an electrician replaced first 2 IGBTs from the left, i put the heater back in the car and the 40A fuse was blown(again) ...and I'm freezing

 

[Cris disrupts]

Nice pics!
What was the issue n solution?

The issue is the lack of heating, the original PTC heater stopped working this spring. 40A fuse was also blown

I purchased an used PTC heater from eBay(from US, delivered to Romania in July) and last week I decided to install it, together with a new 40A 14x51mm fuse.

Now the PTC heater is green, but i still do not get any heat:

From Service mode I ran a Thermal Test and I get this:

Active errors now:

The model number (1060432-00-A) of the heater purchased from eBay(installed on the car now):

The model number (1060432-00-C) of the original heater(removed from the car):

The good part is that I now manage to change the heater and 40A fuse in less than 90minutes...i did this task 4 times in the past week.

Any help and suggestion would be highly appreciated!

 

[brainhouston]

Maybe rev A vs C issue..
Maybe it needs update?.. have u tried soft re-deploy?
THC-w183-PTCCanTmo - sounds like PTC CAN timeout?.. if heater is on CAN network then it makes sense that it can't operate if its can bus not working...

 

[Cris disrupts]

Maybe rev A vs C issue..
Maybe it needs update?.. have u tried soft re-deploy?
THC-w183-PTCCanTmo - sounds like PTC CAN timeout?.. if heater is on CAN network then it makes sense that it can't operate if its can bus not working...

Just completed the SW reinstall:

Still no heat, but fewer active alerts:

I dont know what to try next...

 

[rcho8]

You try Full SW reinstall? maybe the replacement PTC unit is defective.

 

[Cris disrupts]

You try Full SW reinstall? maybe the replacement PTC unit is defective.

I will try this tonight. I hope to not lose the Homelink setup with my garage gate... but most probably the problem is the PTC heater and I need to fix the old one or buy a new one from Tesla

 

[Retkimora]

I dont understand ("It is irrepairable") if you manage to repair the heater presented in the pictures above...or you purchased a new heater.

Please clarify what it is irrepairable!

I have the same issue, an electrician replaced first 2 IGBTs from the left, i put the heater back in the car and the 40A fuse was blown(again) ...and I'm freezing

The actual PTC element is just a passive component. It is like multiple big resistors in one package. One of those "resistors" traces is broken inside the element in my case. You (or your electrician) can measure it with multimeter and see which one has too much resistance.

I think if the logic board is damaged even new IGBTs can blow right away if not driven properly. One should always measure all the other IGBTs and look for potential short circuit before putting it back in with new fuse.

 

[Gtech]

I will try this tonight. I hope to not lose the Homelink setup with my garage gate... but most probably the problem is the PTC heater and I need to fix the old one or buy a new one from Tesla

Did you checked the 12V fuse for PTC heater?