Testarossa Climate blower motor problem .

Greeting, I just purchased a 1990 TR with 42k miles from Exotic Car Auction . It has a electrical problem. The A/C fuse was burn and the blower motor is not working at any speed . I went to put a new fuse and turn ignition on . I immediately smell burn and saw smoke coming from center of A/C Vents. So I removed fuse out and it didn't blow the fuse it was a 20 amp this time . I found services records for the TR and the a/c compressor ,drier,ac press switch was replaced . Previous owner still had problem with smelling burn inside center air vents an smoke . The Ferrari dealership also replaced the fuse box circuit board from GT parts inc. .all done in in 2021 ,700 miles ago. They mentioned in diagnosis that the compressor had locked up internally .So I suspect the blower motor is fried ? I am in the processes to remove the dashboard and then try to see the hvac where the motor lives and I would like to get help here so I can fine the problem of no blower motor operation Thank you all in advance .

 

Did this happen when:

1) the STOP pushbutton was pressed (the blower motor should not even be trying to run) or

2) with one of the other pushbuttons pressed (the blower motor would be trying to run)?

There is a power transistor associated with the blower motor that is mounted in the TR center vent area. If you got the smoke in condition #1, I'd inspected the power transistor. If you got the smoke in condition #2 = could be either the power transistor or the blower motor. Here a pic showing the rivets that hold the power transistor assembly:

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And this is the 127014 Power Transistor Assembly that is riveted in the center vent area:
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Hi Steve Magnusson , I am in process of removing dash as we speak . Here what I just did , I disconnected the power button and the blower motor switch from center console and put back the fuse , and then I just turn ignition on and burning smell was coming from center air vents .

 

If it needs a new fan motor I found VDO PM381 fits.

 

I finally finished removing the dash out of the TR ..and I found the problem it's the power transistor it get hot when I turn the ignition key .. it get very hot and the fire works show starts LoL ..You can see sparks from the left side of the tiny screw from power transistor, look at the picture..this part was replaced before .Now can I just replace it and its show work or the blower motor or something else has problem. Can I test out the Power Transistor on the bench? To see if it does the sparks when I power it ? It has red/blk line ,yellow/green line and orange wires
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Certainly try replacing the power transistor first to see if the blower motor then works. The tricky bit is the mounting of the transistor to the heat sink. The outer case is an active wire (one of the wires might be connected to other end of that screw with the arcing) so can't be electrically connected to anything else -- there should be electrical insulators. Try a search on "TR power transistor" or "2N5886" for prior threads -- IIRC, that stock 2N5886 is rated at 25A, but people have identified other TO-3 transistor(s) that have a higher current ratings.

Shame that they mangled your housing of the AC unit so badly -- just drilling the rivets out is all that was necessary.

 

Can I buy one from online it only like $10 and I can install it to the heat sink with the same part number ? Or I have to buy one one At Ricambi for $187 ? Ebay one is # 2N5886 Transistor Silicon NPN / 80V / 25A / TO-3

 

Yes, you can replace just the transistor itself and reuse the heatsink (but make sure the mounting hardware was not messed up from the prior replacement).

 

Greetings is this the way I should buy just incase I need it ? Its only ebay
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Sure.

 

So the TR has 2 shaft for fan Blades Blower motor ? Just want to make sure I dont see no images of it . Also it located inside of black Hvac box behind the Condenser ?

 

When you diagnose it and take it apart far enough to know what you need all your questions will be answered.

 

I just wanted to know it was the right one, cause there are no images anywhere .I just purchased that one that you gave me the part number anyway just incase I need it ,Thank you btw .The Reason why I wanted to know is that my TR is all dismantle inside and its parked outside and I just want to fixed it so I can installed everything back ,and get it out of harm way . I don't have no more room in my 2 car garage . Can someone tell me where the Hvac blower motor is located ? It is located inside the condenser box ? Thanks in advance .

 

The 2 shaft blower motor? In other auto A/C units, the speed is controlled with simple resistor switch. Why did Ferrari use a transistor ?

 

For the same reason since the close of the Victorian age most manufacturers have used PWM controllers.
Its simpler, cheaper, it causes less fires and it uses much less energy. You also have infinite fan speed control instead of preset speeds.

I told the guy at Rolls Royce school after spending an hour on the massive diagram for their 16 speed fan speed control system using an entire bank of resistors and another bank of relays in various combinations "Why not just use a PWM controller?". I thought his head would explode. They had an entire giant wiring diagram page, about 20 lbs of components dedicated to their fan speed control. It all sat in an insulated space under the hood it generated so much heat.

 

This is not uncommon. It allows the use of two smaller impellers on each end that are more similar in diameter to the motor = it packages smaller/better than a single, larger diameter impeller while giving the same airflow.

Because the TR wasn't designed in 1950? Seriously, the (common emitter) transistor arrangement has some advantages:
1. Provides continuously variable motor speed control.
2. The resistor arrangement dissipates more heat and uses more electrical power. (The transistor also runs kind of "hot" so that's why it's mounted in the output airstream of HVAC unit, but it uses/wastes less power overall.)
3. The resistor arrangement requires more large gauge (heavy) wiring and a more expensive high-current capable multi-pole switch.

I will give Ferrari a bit of a negative mark for not communicating to the HVAC vendor that the transistor needed to be easily accessible and replaceable. It's not super-difficult to do once you know how/where it's mounted, but Jose's photo shows that it's not obvious how to do it correctly.

 

I saw here in the site where they upgraded the heat sink .I just purchased one online and wanted to know if it's a good idea ? Also I read you don't have to mount the power transistor back in The inside of Hvac box, instead you can mounted in passenger side knee bolser . Correct me If I am wrong thanks .
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You can relocate the transistor to a new location, but then it's up to you to ensure that it has enough total cooling (i.e., heat sink + airflow). The transistor is mounted in the center vent to always give it some airflow when the fan motor is operating (but it isn't much of a stock heatsink). I have no experience relocating the transistor nor using a different heatsink, but, if it does fail again, maybe it will be easier to replace in a new location. My "solution" was to only operate the fan speed at maximum (which uses a relay to supply the motor current and not the transistor) or at 1/2 speed or below. Operating the fan at 3/4 or 7/8 speed cooks the snot out of the transistor.

 

Can you please guide me to your solution then . How can I do it this? Are there pics or instruction ? I don't mind running only on high speed at least it will work and its more reliable .and I don't have to use new power transistor .

 

I bought the biggest heat sink I could and mounted it under the passenger side crash bar. It is easy to service and doesn't run burning hot. I'll find a link to the one I bought.

 

https://www.ferrarichat.com/forum/threads/power-transistor-2n5886-heat-sink.657938/

Please see post #10

 

the problem with the Ferrari solution is that the heat sinking is practically non existent with the way it is mounted. blowing air on the transistor itself is not good enough. to further exasperate the problem, you need more sinking the lower the fan speed is.
there is reason why audio/signal power amplifiers sit on fined heat sinks. heat needs to be first drawn away from the transistor to a smaller surface area (fins) where air can then draw away the heat from it.
the solution is really to remote mount the transistor on a proper large enough heat sink..if mounted correctly, convection is enough.

 

I just did it by manually operating the speed control knob in that fashion (after I had replaced my bad transistor with a new one).

 

But even in Texas I only use about 25% fan speed. I get too cold otherwise.

 

Post 2 is the heat sink and fans I used.
Mounted on back side of footwell panel.