So my a/c went out on me and thanks to the help of everyone on this forum and past posts, I was able to determine what the problem was, which in this case was it was the blower control module. So I was able to get a used replacement online and plugged it in to test if the blower would work, and presto it did! I had work the next morning so I didn't put the glovebox in or fit the module back in it's place. The next morning I drove to work and put the a/c on and everything was great, until that night when the blower just shut off out of nowhere after working just fine! I grabbed the module from where it was hanging and it was burning hot! Not sure what it could be and am hoping someone here can shed some light on the situation or share a similar experience? Thanks in advance guys!

 

Hi etaent,

The problem is that the aluminum heatsink on the original control module does not provide sufficient cooling for the power transistor, and either the transistor or the thermal cutoff (a type of fuse) fails due to overheating. To solve the problem, Jaguar introduced a revised module with heatsink fins that are nearly twice the length of the originals. These can be found for USD $200 - $250.

We're having the same problem with our blower control module. We've had some realtively hot, humid days recently, and while sitting in a drive-thru line with the engine idling our blower just quit. I ordered the transistor and thermal cutoff from DigiKey as recommended in these threads:

How roberwil 'stole' from the *******s

https://www.jaguarforums.com/forum/x...er-quit-62390/


I ordered two each of the transistor and thermal cutoff, which was a good thing, because a month later the control module died again, this time sitting in a line of traffic on a hot, humid late afternoon. I rebuilt the control module again, but this time the repair lasted only about 10 days.

I have temporarily jumpered the connector so I can run the fan on high as needed while I await more parts from DigiKey. But in addition to the transistor and thermal cutoff, I've ordered a salvaged heatsink with longer fins from eBay, which I will have to cut down to size. My plan is to replicate the approximate increased cooling of the longer-finned heatsink on the revised Jaguar blower control module.

If you don't want to get into rebuilding the module yourself with a different heatsink, the only option is to purchase a revised Jaguar module. Check eBay for units priced at about $200. After having inspected the circuitry and minimal parts count of the control module, I am going to try everything I can to permanently solve this issue myself before I spend that kind of money a revised part that should have been designed properly in the first place.

Cheers,

Don

 

Unfortunately, leaving the module hanging rather than re-installing it may be what killed it. The module is mounted in the air intake duct (the duct that runs from the cabin air filter) so that while the blower is running, air is forced over the cooling fins. With the module not mounted, no forced air cooling.


Ray

 

Good catch, Ray! I had missed that detail in the OP.

Cheers,

Don

 

Wow thanks guys! I didnt think of all that and thats why i mentioned everything i did, and i am glad i did! I will order a new module with longer fins and do the full installation this time!

 

I had the same issue earlier this year when the temperatures started picking up here in California.

I had mine replaced at the dealer and verified that they were using the new/revised part number. I've left the AC/Climate Control on Auto since then and the fan has worked flawlessly since the repair. The dealer mentioned that maintaining good flow over the fins is important (i.e. keep the controls on auto so you have constant airflow and also make sure the cabin filter is changed every 2 years to maximize the airflow over the fins)

Hope this helps.

-cajag
2006 x350; lwb

 

Ok i have installed the new module with the longer fins, got it for 199.99 including shipping on ebay! I have a\c and heat again! It is safe to say that this was resolved! Thanks for the help! Gotta love this forum!

Heres the link to the module---> Jaguar 2003 09 XJ8 XJR Front Blower Motor Resistor Control Module C2C39577 | eBay

 

Hi folks,

Is the thermal cut off different from the module? I am working on a 08XK.
Blower motor went bad from water leaking in the box from improper drainage from evaporator box.

Lowered the trans, cut off the duck-bill end, installed new blower motor and module (didn't check if it is the updated one w/ longer fins), and checked the blower fuse, which hadn't blown.

Still have no blower! Haven't checked to see if I'm getting current to the blower but would like to know about this thermal cut off, as I hadn't heard of it.

Thanks for all the help!

Best,

Stangohr
Aiken, SC

 

Hi Stangohr,

Welcome to the forum!

The thermal cutoff or cutout (TCO) is a small electrical component that is part of the Blower Control Module. The TCO acts like a fuse to protect the rest of the circuit, but it reacts to high heat instead of high current. It's about the size of a resistor and is positioned so that its body is in contact with the heat sink that cools the power MOSFET transistor. If the temperature on the surface of the heat sink exceeds 114 degrees C, the thermal cutoff opens (permanently, like a standard fuse) and the BCM will no longer function. For information on how some of our members have repaired their BCM by replacing the TCO and transistor, see the thread below. The parts are very inexpensive from DigiKey: the transistor IRF1010EPBF-ND is USD $2.47 and the thermal cutoff P10920-ND is $0.74.

https://www.jaguarforums.com/forum/x...er-quit-62390/

The real problem with the BCM is that the original heat sink is under-engineered and in certain circumstances it fails to properly cool the transistor, prompting the TCO to open. In our '04, the circumstances were while idling in a line/queue of stopped traffic on a very hot day (90+ F / 32+ C). The revised Jaguar BCM has a heat sink with fins nearly twice as long as the originals to improve the thermal dissipation and keep the transistor cool.

Please visit the New Members Area and post an introduction so we may all know something about you and your car:

https://www.jaguarforums.com/forum/n...-intro-must-5/

Cheers,

Don

 

Hi folks,

Due to own stupidity I grabbed the ORIGINAL (fried) blower control from the bench and installed it with my new motor. I removed it and installed tne new one and all is well.

Wish I had known about the improved version with the longer heat fins, but I will save this fried controler and rebuild it, thanks to your help!

Best,

Stangohr
Aiken, SC