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PEM overheating, fans not running

jordanthompson

2018 P100D Model X
Apr 27, 2011
589
53
Satellite Beach, FL
I got the Roadster back from service (again) and after driving it for a few weeks the PEM is overheating. I had to limp home yesterday and it charges very slowly.
I had the fan assembly replaced about 6 years ago.
This is a 2010 2.0.
I'm guessing that the squirrel cage fans fuse has blown, but I can't find it. I checked the fuses in the cabin and also checked the high voltage door but didn't see anything small enough to be the right fuses.
Any suggestions?
 

gregd

Active Member
Dec 31, 2014
2,530
1,767
CM98
Thank you Stefan! I replaced the fuse and everything is working fine! The fault lamp on the dashboard is gone also :)
So, now the remaining question is why did the fuse go? Was it a mechanical or electrical stress caused by prior work on the car, or is there something else still at fault which could cause it to go again? Time will tell...
 

jordanthompson

2018 P100D Model X
Apr 27, 2011
589
53
Satellite Beach, FL
I know what you mean... The car has been in and out of the shop (replaced the battery twice) so anything could be the problem.
We live in Florida and it is hot and I was pushing it when I noticed the power drop, so maybe that is the problem. It could be a bad fuse. Of course it could be something much worse coming down the pike.
 

Rolf68

Member
Jul 24, 2015
235
145
France
Hello.

Glad you could repair the PEM. Any picture or technical info of the faulty fuse to replace for reference maybe?

Best regards :)
 

jordanthompson

2018 P100D Model X
Apr 27, 2011
589
53
Satellite Beach, FL
Not really, the fuse is 20 Amps. The hardest part was locating them inside the compartment (the are on the back side wall of the opening and you can only see them if you lean under the trunk lid and look back towards the back of the car.) It was very straightforward.
 
  • Informative
Reactions: markwj and Rolf68

Rolf68

Member
Jul 24, 2015
235
145
France
Not really, the fuse is 20 Amps. The hardest part was locating them inside the compartment (the are on the back side wall of the opening and you can only see them if you lean under the trunk lid and look back towards the back of the car.) It was very straightforward.

Thanks for the precisions :)
 

jordanthompson

2018 P100D Model X
Apr 27, 2011
589
53
Satellite Beach, FL
I was out again today and sure enough, the fuse blew again :-(
The motor blower is fine, its the PEM blower that keeps going. I looked under the car and they LOOK clean (I haven't tried turning them by hand to see if there is any resistance.)

Any suggestions?
 

gregd

Active Member
Dec 31, 2014
2,530
1,767
CM98
I was out again today and sure enough, the fuse blew again :-(
The motor blower is fine, its the PEM blower that keeps going. I looked under the car and they LOOK clean (I haven't tried turning them by hand to see if there is any resistance.)

Any suggestions?
So, you have two separate motors, not the single motor / dual blower upgrade?

The only thing I can think of is that the motor is bad, and drawing too much current. Bad bearings, for example. Seeing if they turn easily would be a good test to make. Compare with the other motor (they are identical, right?). I presume that there aren't any twigs or rocks that could have caused the motor to stall, and that the air channel is otherwise good (not blocked).
 

jordanthompson

2018 P100D Model X
Apr 27, 2011
589
53
Satellite Beach, FL
I took off the skid plate and it occurred to me: they replaced two separate blowers with a single one (motor in the middle of the two blowers) in 2012, which explains why the motor blower fuse is intact (I assume that they abandoned the motor blower circuit). I turned the assembly by hand and it seems to rotate smoothly with little resistance. Does anyone know if the single motor assembly only needs a 20A fuse?

The fans look completely clean from the outside (without taking the assembly off the car.)
 

gregd

Active Member
Dec 31, 2014
2,530
1,767
CM98
I think the question really is, what exactly does that fuse connect to? It clearly is up-stream of the motor, but what else?
 

Rolf68

Member
Jul 24, 2015
235
145
France
Did you check the blower connector (under the PEM, the 4rth one, far right) ? It appears it can degrade with time and even could burn / melt . Maybe it's a cause of the fuse blowing ?
 

gregd

Active Member
Dec 31, 2014
2,530
1,767
CM98
So, sanity check on the fuse(s)... Understanding how the system is fused may help locate the fault. If at one time there were two motors, now one, there could have been a pair of fuses, with now one not being used, and the other being a higher value. This would be downstream of the driver circuitry.

Or more likely, as I believe there are the two driver circuits, once independent (i.e. one for the motor, one for PEM), now wired in parallel at their outputs, so each is probably fused separately upstream of the driver itself. If this is the case, perhaps the other fuse is also open, so all the current is being pushed through the single remaining one (the one you have been replacing)?

TL/DR... Perhaps there's another fuse (probably also 20A) that's also open, and both need replacing?
 

jordanthompson

2018 P100D Model X
Apr 27, 2011
589
53
Satellite Beach, FL
So I called the service center and it turns out the fan assembly was replaced just over a year ago (we have been having no end of issues with this car for the last year and a half and I honestly forgot that this was done.) Anyway, the head tech graciously offered to repair it under warranty even though it was over 12 months. They picked up the car today, dropped off an ICE loaner and now I wait.
I have always been so impressed with Tesla service (although they do tent to cause a lot of additional problems): they really try to make the customer happy.
 

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