Very strange. I don't know what is going on here. I don't have any good theories. Maybe there is an intermittent short in the radiator fan temperature sensor circuit. Maybe when you did your earlier tests, the AC was off or at low cooling demand and the receiver/dryer switch was not active. The receiver dryer switch is triggered at 15 bar (217psi) which I am told is only achieved at higher demand. I'm not really convinced though. Your fault didn't sound intermittent before. I wonder if the new temp sensor/switch is faulty? It's normal if the AC demand is high. Was the cabin hot and the AC temperature set low? If so, maybe do your tests at night or on a cooler day? Because the fuse is hard to get to, I've never checked the normal current going through that fuse. The fuse is powering the blower motor and the compressor clutch (as well as some of the ECU circuits). Maybe someone else knows? When you say the fuse was "burnt", do you mean the plastic was melted/black, too? Or was it just the metal element that was broken? Is the fuseholder ok? I would replace the fuse (and holder) with a bullet type glass fuse at some point in the future. I don't know why Ferrari made that fuse so inaccessible. They moved the fuse to the cabin area on the 360 and F430.
I make my test into my garage (18-20deg celcius), engine cold (last time a start engine was few weeks ago). About the sensor temperature switch, i put the old one (because no difference with the new one...) If the dryer switch is broken it can send wrong signal and power ON the radiator fan? I need to test it. About the hidden 30amp fuse the holder is little melted. Maybe there is problem with the AC compressor? Tomorrow i will go for a ride and test AC. Other problem is flip flap motor and direction vent motors are not moving. I suspect the siemens chipset on hvac ecu. I am waiting for these parts and change all of them.
When you disconnected the dryer switch previously, the fan didn't stop, so it can't be the dryer switch keeping the fan running. It can however be the dryer switch wiring (from the connector to the LH fan relay). The wiring may be shorting to earth somewhere, but intermittently. There is no need to test the switch. Anyway, with the AC switched off, the switch should be open circuit. i.e. test for (no) continuity between the blue wires.
As Cedrik informed in posts #24 and #25, the fan stopped when he disconnected the dryer switch and, when connected, the fan was going "off" and "on" with the AC panel switch "off" and "on" (which is normal when the dryer switch is "on"). In his previous dryer switch disconnection, the reason why the fan did not stop could have been because it was at the time when the engine was hot so the fan was kept "on" by the thermo-switch on the radiator. With the AC is switched "on" at the AC panel and the engine cold (or the radiator thermo-switch temporarily disconnected), if the dryer switch keeps the fan "on" when it shouldn't, like immediately upon engine start or coming "on" too soon after the engine has been started, the reasons could be: 1. The AC system has been overfilled with refrigerant. 2. The dryer switch (its fan switching segment) could be faulty. It may still switch "off" when the AC compressor is not running but it may switch "on" prematurely, i.e. at lower pressure than it is designed for. However, on a hot day and the temp set on the panel to rather cool, the dryer switch may keep the fan "on" almost all the time, especially if the car is not moving or moving slowly. So, I would make sure the AC system is not overfilled (was any work on the AC system done recently?) then test the dryer switch operation again (while the engine is still cold or with the radiator thermo-switch unplugged). With the AC switched "on" at the panel, if the fan still comes "on" very soon after the engine has been started, replace the dryer switch. At what pressure the dryer switch comes "on" (switching the rad fan "on") can be tested if the AC pressure gauges are connected to the system. These switches are rather standard and universal ones are easily available, coming with pigtail wires. Example: Image Unavailable, Please Login Typical switch pressure settings: Image Unavailable, Please Login Typical pressure switch wiring: Image Unavailable, Please Login
Definitely need clarification on this. That's the trouble with remote diagnosis, you don't always have the full details.
Ugh... If you're 100% sure of that, we are back to some kind of intermittent wiring fault (including the relay panel) .... unless Miro can think of something else. Well, the AC won't work as the compressor also uses a separate switch inside that dryer/receiver pressure module. Other than that, no problems. I'd be curious to know what would happen if you drove around with both the dryer plug and the radiator thermo-switch plug disconnected, but I'm not going to recommend that Would the fan start running?
You, of course, may still have a pressure switch issue or gas overfill issue. If the demand on the AC system is low, the switch shouldn't be activating. At the moment, does the fan still run if the temperature is set to high with the AC ON (i.e. before the engine gets warm).
As Ian said, you may drive with the dryer switch disconnected because this will (should) cause the AC compressor to be "off". However, to avoid any possible risk (to be extra cautious), also keep the AC system "off" at the AC panel. Operation of the dryer switch: 1. The "Low Pressure" segment of the switch will switch the compressor "on" if there is sufficient refrigerant (sufficient initial pressure) in the system; otherwise, the compressor will not come "on". 2. In the normal operating pressure range, the "Fan Switch" segment will cycle the rad (condenser) fan "on" and "off" as required to maintain the normal pressure. 3. If, for any reason, the AC system pressure cannot be maintained within the normal range and goes too high, the "Low Pressure" switch will, at a pre-set high point, open again and switch the compressor "off". So the "Low Pressure" switch is actually dual and it goes as: too low pressure - OFF ; normal pressure - ON ; too high pressure - OFF.
The fuse probably gets hot because the sockets in the fuse holder are partially corroded/burned and do not provide tight contact with the fuse pins. This creates some resistance at the fuse sockets which acts as heater. Replacing the factory small 30 A fuse and holder with a bigger (still 30 A) heavy duty fuse is a "must do" thing on the 348s and 355s (especially if you don't like seeing cars on fire). Comparison of the factory fuse and a "Maxi Fuse" (both 30 A): Image Unavailable, Please Login This is my installation (348) of a Maxi Fuse using large 9.5 mm female spade wire terminals: Image Unavailable, Please Login There are other shapes/designs of large inline fuses like: Image Unavailable, Please Login ANL Fuse
I vaguely recall someone fitting a window into the luggage compartment liner so he could view the fuse. Would have been better if it was an opening window
I just come back from a ride : Dryer switch disconnected. internal blower power to position 0. When i stop engine the radiator fan was ON (because engine was hot). After few seconds i just turn ignition (engine no running) and the radiator fan was still ON (i assume this is normal because engine was still hot). I just turn internal blower to position 1 on hvac then radiator fan go OFF (when i go back to position 0 the radiator fan go ON again). If the AC "stop" button is activated (so AC shut down) then i can put blower to position 1-2-3-4 and radiator fan is still ON. Now i need to wait engine beccome cold to see if radiator fan is OFF when i put ignition About the 30amp fuse holder i just order a rearmable fuse
1 hour after the radiator fan is go ON when i put ignition ON and blower to position 0. If i put ignition when blower position is at 1 or more then radiator fan is OFF...
Take the relay E7 out (passenger compartment panel), repeat the test as above and let us know the result.
It sounds like you have some illegal modifications. Or someone at the factory thought that radiator "fan" meant blower fan. Maybe the hidden 30amp fuse is powering the radiator fan? And it gets overloaded when you try to use both. Perhaps it's time to look at the back of the relay panel (as previously suggested)... after you've pulled the E7 relay, of course.
I think i see the problem : the 4 wires from harness with connector for dryer switch are totaly melted together. It's possible this tiny harness was touching the very very hot 30amp hidden fuse and burn. Now i need to replace the 4 wires (blue, black, green, green/black) because they are melted far away...
Do you think it's possible 1 of these 4 wires have problem and became very hot for melted with the 3 others? Or it's "external" issue (touching the 30amp fuse)
Ugh.... Can you post a photograph the damage please. Both the fuse wires and the dryer (green) wires carry a lot of current. Maybe the heat of both contributed to the melting of fuses and wires. Also, one of those dryer wires is an earth wire. If they touched the AC fuse wires, you would have a short to earth.
To me, it looks like the dryer harness was pushed hard against the fuse. The fuse caused the dryer harness black insulation to melt. I guess when you carefully cut back the insulation, you'll see which wires are damaged.
By the way, a resettable fuse is not going to fix your melting fuse issue. As Miro says, it's probably poor contact between the fuseholder and the fuse which is causing the heat. You can buy maxi fuse holder kits... https://www.ebay.com.au/itm/132864420609 or just go with Miro's suggestion of fitting spade connectors (with thermofit around them to prevent shorting)
Hard to tell because the wires are litteraly mixed together... and also with external insulation. I will replace these 4 wires from here to connectors A, C, "41050", "30008". The 41050 is the white on the side of evaporator unit box, this is right? Do you know where is the 30008?
