355 Heater fans

Found this. https://www.ferrarichat.com/forum/threads/355-hvac-fuse-question.599105/

I think the 355 the hidden fuse affects the heater and the fan but not the clock etc. Here you can see I replaced it with a glass bullet holder (screwed to the side of the blower box) . The plastic holder is under rated for the load and they tend to burn up and melt.

Not sure of that's the fuse your referring too.

 

The 30 amp fuse also sends battery power to the AC compressor clutch and the HVAC ECU.

Did they remove the compressor clutch from the circuit (for faultfinding purposes) by unplugging the pressure switches on the receiver dryer or unplugging the (rearmost) of the green relays shown in Eric's photo?

The "heater" fan they refer to is the blower (for cold and heat) in the forward luggage compartment. It can't be replaced/repaired. You would have to change the entire aircon unit (dash out job).

 

Receiver dryer plug shown below (next the battery cutoff switch).

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Note that disconnecting the plug also stops the LH radiator fan running when the aircon is turned on.

Thanks to Elliott for the photo.

 

Since there are a few causes for a blown fuse, I wouldn't panic too soon. If they say it's the blower motor, ask them how they know the compressor clutch isn't causing the fuse to blow.

 

Actually, now that I remember, removing the relay gave some unexpected results on one owner's car (Can't find the message thread). There may have been some extenuating circumstances, however. Unplugging the pressure switches may be the better option or, even simpler, pushing the STOP button on the HVAC panel (That should allow the blower fan to run, but stop the compressor clutch engaging).

 

I assume he means the fan regulator. This has been discussed elsewhere. We don't believe it's possible for this to blow fuses. Even if the unit was shorted, it just means the fan would run at the (normal) max setting.

Miro is our resident expert on these.

https://www.ferrarichat.com/forum/posts/147899331/

It may be time to ask for a second opinion.

Yes, I would certainly keep the old one. Miro may be able to repair it if it is broken.

P/N 63307200 I'm surprised you can still find these or will it be a used item?

 

Here's a thread on the internals of the fan speed regulator/power unit.

https://www.ferrarichat.com/forum/posts/144926634/

 

Interesting diagnosis. As Ian suggested, get a second opinion.

Most likely, your blower motor is drawing excessive current (seized or having shorts in its windings) which overheats the Power Unit and blows the fuse. Another point is that new Power Units are not available so it is not clear what the dealer would do for $1070. In any case, putting another good Power Unit may result in it also overheated and blown.

You can test the blower motor if you unplug the larger connector from the Power Unit and bridge the two spade sockets as shown on the pic. If the motor is good, it will run at full speed; if it blows the fuse, it has a fault. Do not try to run it with a higher than 30 amps fuse.

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i.e. short the big brown and black wires together on the orange plug (on the F355).

You can see the orange plug in this photo (ignore what the gloved hand is pointing to):

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Unfortunately, shorting out these pins (sockets) will turn the fan on at high speed whenever the ignition is turned on. You won't be able to use the HVAC control panel to turn off the fan. It's not something you would want to do prior to a long trip.