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Discussion Starter #1
I pulled this of another site. Thought I would share..


August 19, 2003:

Applies to:
2003 Pilot EX- From VIN 2HKYF18..3H000001 thru 2HKYF18..3H604126

Symptom:
The rear center vents do not blow air at any climate control setting.

Probable Cause:
The power transistor for the rear blower has an open circuit.

Corrective Action:
Replace the rear power transistor.

Customer information:
The information in this bulletin is intended for use only by skilled technicians who have the proper tools, equipment, and training to correctly and safely maintain your vehicle. These procedures should not be attempted by "do it yourselfers" and you should not assume this bulletin applies to your vehicle, or that your vehicle has the condition described. To determine whether this information applies, contact an authorized Honda automobile dealer.


(Oh really now)

:ucrazy:
 

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gopilot, wow, my Pilot actually falls under the TSB for this one. But I've never had a problem with the rear blower not working. Well, actually, I've never sat in the 2nd row, so I personally wouldn't know, but my kids never complained about the AC or the heater not working in the back.

Does Honda send out letters for TSB's as well or is it just for recalls? Considering the VINs, am I correct in assuming that this is just for the Canadian Pilots? Also correct in assuming that the TSB's for well over 60,000 Pilots?
 

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Interesting....my VIN is higher than that, and I do have problems with my blower. Sometimes no air comes out of the back vents, regardless if I have the system on auto to keep it one temp., or if I turn on the rear unit so the kids can turn the knob.....there just isn't air blowing. I never reported it because it just seemed random, and I honestly forgot with my long list of other complaints....
 

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My Pilot falls in this range and I did have a non-functional rear blower when the car was delivered. But when I took it in for repair the technician found that there was a connection inside the center console that had never been made during assembly. In other words, they forogt to plug it in. Nothing needed to be replaced. They plugged it in, put it all back together, and it's worked fine ever since.
 

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Discussion Starter #5
RipRocK said:
gopilot, wow, my Pilot actually falls under the TSB for this one. But I've never had a problem with the rear blower not working. Well, actually, I've never sat in the 2nd row, so I personally wouldn't know, but my kids never complained about the AC or the heater not working in the back.

Does Honda send out letters for TSB's as well or is it just for recalls? Considering the VINs, am I correct in assuming that this is just for the Canadian Pilots? Also correct in assuming that the TSB's for well over 60,000 Pilots?
Rip, As far as I know, Honda will not send out any letter's for TSB's unless it is a recall or they feel it is a safety issue. My rear blower seems to work fine, but I remember a few members on this board who said theirs do not work at all. This may apply to them.
 

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refurbished rear ac transistor

Greetings!

I'm a 2003 EX-L Pilot owner and electrical engineer. Every Pilot owner I knew had a broken rear AC (including me), so I did some investigating. The problem with the Rear AC Motor Power Transistor is that there is a filter mounted in the center console that requires cleaning, but is not normally user serviceable. This causes the transistor board to fail because of high temperatures and load and no airflow to cool the component's heatsink. This in turn causes a thermal cutoff to trip (think of it as a sort of fuse) making the board inoperable. I have successfully repaired my transistor board and reinstalled it. Its worked for a few months now, and its not deteriorating. If you guys are interested in saving some money on these repairs, I could refurbish your boards for you. The minimum order for the thermal cutoff from the vendor I used was 30 units, so I have 29 left. Its the factory component from the original manufacturer honda used. I'd do parts and labor for $30, and include detailed instructions for removing and reinstalling the part (its just a plug-in part, and only involves removal of the driver's side center console access panel which just pulls off with spring clips) If anyone is interested, please email and we'll work out the details. If the problem is not with your transistor board thermal cutoff, I'll just mail it back to you and let you know so you can reinstall it and let honda do their thing. $80 is way too much for this part though. I wouldn't pay it, and you shouldn't either.

Look forward to hearing from those interested!

-Jeremy
 

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Re: refurbished rear ac transistor

qu37zal said:
Greetings!

I'm a 2003 EX-L Pilot owner and electrical engineer. Every Pilot owner I knew had a broken rear AC (including me), so I did some investigating. The problem with the Rear AC Motor Power Transistor is that there is a filter mounted in the center console that requires cleaning, but is not normally user serviceable. This causes the transistor board to fail because of high temperatures and load and no airflow to cool the component's heatsink. This in turn causes a thermal cutoff to trip (think of it as a sort of fuse) making the board inoperable.
Look forward to hearing from those interested!
-Jeremy
Maybe you could also do a picture post showing us how to clean/change the filter?
I have an '04 Pilot and it is probably pretty dirty, fan still works though.
 

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Does anyone know if the front blower transistor module and the rear blower transistor module are the same part or interchangeable parts?
 

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archie,

thanks for posting that. Good to see that the repair may be eligible for goodwill treatment.
 

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N_Jay said:
Does anyone know if the front blower transistor module and the rear blower transistor module are the same part or interchangeable parts?
Over at Majestic, I see this for the front HEATER BLOWER:
824997 TRANSISTOR ASSY. $60.31

and this for the REAR HEATER UNIT:
1442475 TRANSISTOR ASSY. $63.55

Part number 1442475 is the unit I found when I searched by Honda's part number (79330-s3v-a51) shown in the TSB above.

The two transistors have look different in the schematics too.
 

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Re: Re: refurbished rear ac transistor

mikey159 said:

Maybe you could also do a picture post showing us how to clean/change the filter?
I have an '04 Pilot and it is probably pretty dirty, fan still works though.
From the second page of the service bulletin, I think the intake screen is what needs to be cleaned. So, pull off the driver's console side trim and vacuum the intake screen?
 

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My intake screen was completely occluded. When I get a chance I'll pull my Front Power Transistor Module and see if the thermal cutoff is the same component. However, I doubt that the simple thermal cutoff fix would work for a front transistor failure. The broken rear-ac units due to transistor failure are a result of the screen pictured in the prior posts being totally packed with dust and the dealers (to be fair, maybe just in my area) not cleaning them as part of the routine maintenance. I know they replace the cabin air filters regularly. When I get home I'll take a snapshot of a thermal cutoff and post it. You can compare that to the guts of your failed front power transistor and check for continuity across it. If its a short, thats your problem.
 

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qu37zal said:
My intake screen was completely occluded. When I get a chance I'll pull my Front Power Transistor Module and see if the thermal cutoff is the same component. However, I doubt that the simple thermal cutoff fix would work for a front transistor failure. The broken rear-ac units due to transistor failure are a result of the screen pictured in the prior posts being totally packed with dust and the dealers (to be fair, maybe just in my area) not cleaning them as part of the routine maintenance. I know they replace the cabin air filters regularly. When I get home I'll take a snapshot of a thermal cutoff and post it. You can compare that to the guts of your failed front power transistor and check for continuity across it. If its a short, thats your problem.
Mine shows a open between the pins as shown in the TSB.

Does the thermal cutoff open or short when it trips?

I thought most transistors fail short. (which could be why they put the thermal breaker in)
 

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The thermal cutoff fails open, just like a fuse. There's a conductive material in it that is supposed to break the connection at 115 C. The transistor is tightly coupled to a heatsink with thermal compound, and the cutoff is sandwiched in there too. I don't believe the intent of this cutoff is to protect the transistor, since Honda discards the transistor modules rather than refitting the cutoff. I believe it is a safety measure to prevent fires or damage to the center console. The heatsink depends on the airflow of the whole unit to cool it, and if that airflow gets restricted by the clogged filter the heatsink becomes completely ineffective. In this scenario, the transistor isn't damaged but the cutoff fails anyway. I've fixed two pilots like this already, and the repair holds as long as the airflow is still good. Its possible that the original thermal cutoffs were defective in some way too, or that the thermal compound is failing catastrophically. I use good cpu heat sink compound when I tear them down to replace the cutoff. I'd recommend anyone trying this repair to do the same.
 

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qu37zal said:
The thermal cutoff fails open, just like a fuse. There's a conductive material in it that is supposed to break the connection at 115 C. The transistor is tightly coupled to a heatsink with thermal compound, and the cutoff is sandwiched in there too. I don't believe the intent of this cutoff is to protect the transistor, since Honda discards the transistor modules rather than refitting the cutoff. I believe it is a safety measure to prevent fires or damage to the center console. The heatsink depends on the airflow of the whole unit to cool it, and if that airflow gets restricted by the clogged filter the heatsink becomes completely ineffective. In this scenario, the transistor isn't damaged but the cutoff fails anyway. I've fixed two pilots like this already, and the repair holds as long as the airflow is still good. Its possible that the original thermal cutoffs were defective in some way too, or that the thermal compound is failing catastrophically. I use good cpu heat sink compound when I tear them down to replace the cutoff. I'd recommend anyone trying this repair to do the same.
Well mine is open.
Mine failed during a very hot spell, but I doubt the inside of the car got to 115. LOL

It was also first thing in the morning after a fairly good lightening storm. I wonder if the part is somewhere static sensitive.

My thinking is a part like this is usually designed to protect the rest of the circuit (and car) from several types of failures, including a shorted transistor (would make the fan run full speed). that would still take some amount of time before the temp rose enough to trip it at 115 deg. Does the part also have a max current spec? (and act like a traditional fuse?). Does it self heat under high current loads, maybe causing a trip?

How much for just the part?

Edit:
Hmmm, flipping through the DigiKey catalog, maybe a self resetting thermal switch would make a great "upgrade"?
 

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The heat sink is very warm to the touch when the part is operating normally, but not so hot as to burn you. It does have a max current rating also, I believe it was 15A. Its probably just an artifact of the conductive material breaking down due to heat. The cutoff resembles a small resistor in packaging, and would heat up with that much current very quickly.
 

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I'll mail just a cutoff for $8 shipped if you like, or $10 if you'd like a spare to keep also. Private message me with your address and I'll get them in the mail to you. I'll give you my details in response so you can mail a check. I don't really mind if you wait to mail the check until you get them, just don't stiff me. :) Make sure you have a decent iron, some flux, and a desoldering wick or gun. You'll need to desolder some enormous blobs to get the part out cleanly. They really slathered it on. Same goes for any other interested parties btw.
 
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