HVAC Fan keeps running

Which relay did you change? I had the exact same problem and swapped out the front relay which is the fan control. The relay towards the back of the car is for the compressor.

When you say under the hood - do you also mean under the black liner?

 

Don't have your solution, but my 348 does this occasionally due to some loose connection I have yet to find.

Occasionally I will start the car, and the fan goes full blast, just as you described. Once driving, if I take a corner or stop hard, it will usually return to normal.

I suspect a loose electrical connection somewhere between the panel and the relay, but it hasn't annoyed me enough yet to pull things apart again.

Hope this helps.

 

Same thing happened on my 355, had to pull the fuse to stop the blower but lost the instruments as they are on the same fuse! Replaced the fuse and the blower came back on full. Finally fixed the problem by resetting power with the battery isolator. I think the hvac ecu can get confused? Anyway worth a try!

 

Having this same issue on my 1990 348. Anyone find any definitive root causes or solutions to this?

Thanks,

Jason

 

Hit/push the stop button and the recirc button on the control panel. That works on my car.

 

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Jason was asking about the F348, Paul. The 348 has a different control panel with integral ECU, but thanks for the tip on the F355

 

Mine did this once 10 years ago. Reset and it has been good. Knock on wood. It was a long time ago but the flapper motor was giving problems around the same time and was fixed as well. Maybe they have something to do with each other cannot remember.

 

This is what fixed mine, havent figured out just whats wrong yet.

I have done multiple battery resets and its still there.

I'll be troubleshooting mine soon.

 

Thanks for the feedback guys.

Ill start with checking electrical connections, spraying with contact cleaner, and making sure the micro relay is working. Part number 63306800 is the relay.

I'll report back on what I find. In the interim, if anyone has any othert suggestions, would love to hear them.

Thanks!

 

Hi Jason

It could be your speed regulator is broken.
It is mounted in front under the fan housing. If you disconnect the control plug you know if it's the regulator or the ECU.
You find threads on it over here.

 

Thanks Patrick. That is tied to the 63307200 power unit, correct?

Do you happen to have a pic of the unit and which plug is the control plug you reference? The car is new to me and i'm not very familiar with it yet!

Thanks,

Jason

 

This is a good thread.

https://www.ferrarichat.com/forum/threads/348-fan-power-supply-module.494608/#post-144092040

The module is situated at the left side under the fan"box"
You have to remove the interior trim from the front hood.
The control signal is the small connector.

 

It can be hard to spot because it's hidden by a lot of pipes. It's Item 2 in the following diagram, but it doesn't show where it's located.

https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/348-group/348/evaporator-unit-and-passengers-compartment-aerating.html

Look beneath Item 5 (forward left hand bottom corner of the fan box). The large luggage liner piece just forward of the windshield wipers has to be removed. This involves lots of fiddly screws which can be dropped into places where they can't be found/extracted.

 

Correct. Not easy to remove. I used a magnetic screwdriver. It is just below the little water pump.

 

Here a photo from the inside.

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Sometimes the transistors are defect. Short circuit = fan alway's on max speed or open = no fan speed.

 

Thanks guys. Is it possible to take a pic from further out so i can see the general area a bit more? Still not sure what im looking at! Thanks!

 

Unless someone already has their forward luggage compartment liner removed, then you may be waiting a while, Jason.

From the left hand side of the car look at the side of the fresh air inlet box/fan assembly which is facing you. On the forward edge of the inlet box look down towards the bottom of the box. Around the forward bottom corner you will see a couple of small electrical plugs going into a device there. I've previously tried to take a photo of it on my F355, but there are too many pipes in the way. I don't know if the plug colours are the same on the 348, but I think one is orange.

It's under item 5 in the diagram:

https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/348-group/348/evaporator-unit-and-passengers-compartment-aerating.html

It's Item 2, and the orientation is correct. It's just that the diagram has shown it well away from the air inlet box (It's actually mounted on the box).

 

The fan speed controller is pointed at by the red lines on the attached pictures. On the third pic, the red line points at the small connector that you need to disconnect for testing. If the fan still runs at the full speed, the fault is inside the speed controller. Let us know.

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Thats great! Thanks!

Would you be able to highlight where the micro-relay is by chance, please?

Im thinking I will first try pulling and resetting the fuse to see if it might trip the relay that could be stuck. Ive ordered a new micro-relay and will try that first.

Next will be the fan speed controller. I should have some time this weekend to try and diagnose. I'll report back.

Greatly appreciate the help! Thanks!

 

I can't believe how easy it is to access the controller on the 348 (unless some modifications have been carried out on that car?). Far easier than on my RHD F355.

There are two relays mounted on the opposite side of fan/intake assembly. i.e. on the right hand side of the car. See items #11 in the parts diagram:

https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/348-group/348/evaporator-unit-and-passengers-compartment-aerating.html

According to the wiring diagram, it should be the relay with the most wires attached to it (seven), including some heavy duty (4amp) red and brown wires. Perhaps Miroljub can tell you if it's the forward or aft relay.

 

Easy on my 348 as I have removed the heater pump and valve and plugged the hoses (the heater is not really required in Malaysia).

The problem with the blower fan running at full speed has nothing to do with the relays (means the relays are good) but it can only be the speed controller or the AC ECU. I don't know if the AC controls on a 348 have "Auto" mode as I have completely modified my (originally dead) AC ECU. If it has the "Auto" mode, then it could also be one of the temp sensors.