Mondial Climate Contol Knob System

I do NOT have either problem, so I would say either something is amiss, or perhaps just part of the Ferrari charm.

I am GUESSING the fan switch is simply a rheostat type switch since it is infinitely adjustable. So the rheostat is worn over some of its surface area, except at either extreme.

The hot/cold must control a flap somewhere that allows warm air from engine heat to mix with outside/cold air. It dos take about 20-30 seconds on mine for the air to remix after I have moved the switch to either extreme.

I would think some of the more experienced folks here can explain the system with more precision so you can track down the gremlins.

Regards,
Jerry

 

I've got the same behaviors as the OP. Fan is only off or full blast. Thermostat is only "HOT" or "COLD".

Not only do I suspect the rheostats, but the whole assembly... could be the fact that the controls don't get full voltage (thanks to Ferrari's great prowess with electrical design) and the motors won't kick on unless the rheostat is at 100%. Could be the servo(s) that drives the the flaps / valves are gummed up (like the window motors like to get) and won't make fine adjustment.

I'm attacking the electrical system first. Replacing the fuse board, some connectors, etc. to make sure everything is getting all the juice it needs. Then after that I'll see what's what with those old rheostats. I'll post up if I find a suitable replacement that's not OEM.

 

I'm guessing but believe that in addition to the rheostat the fan control has a point at the end of it's travel that becomes or triggers a switch. Mine still works for varying speed, but when I get near the end of the travel it definately switches to full blast.

I've had issues with my temp switch so I only run the fan if I need heat, otherwise the system is off.

 

The fan speed knob controls a power transistor, which in turn controls the fan motor speed.
It does have a micro switch at its "max" position that overrides the power transistor and supplies full voltage to the fan motor. The left hand side of the three relays below the ip controls that maximum power. It also has a "off" position with a click at the other end. However:
Once you press any of the 3 buttons (A/C, A/E, Defrost) the fan must run, even if it is at it's "off" position. (It'll run at minimum speed in that case)
The temperatur control knob inputs your wish into the a/c ecu. It's compared to the cabin air temp. signal (the small suction fan next to the steering column sucks in air past a sensor). The ECU then decides to use either A/C or the heater to get the cabin air temp to your wish.
Additionally:
The sensor at the evaporator will cut the A/C if freezing is likely to occur; the blow air sensor in the central exit adjust the heater valve function if large OAT changes occur.
The workshop manual describes how to test the sensors and knobs with an Ohm meter.
That is where I'd start

 

Nice info. I will get on it.

 

Also, regardless of the hvac button positions, incl. "OFF":
- the hvac ecu and all the sensors are under power with ignition "on"
- the suction fan must be running
- the heater valve gets 12V

- The center relay below the ip feeds the power to the a/c clutch via an integrated relay inside the ecu. It's "on" as soon as the any of the three hvac buttons is pressed, allowing the ecu to control the a/c clutch.

- The rh relay below the ip grounds the heater valve when the hvac is "off", closing the heater valve (otherwise the heater would be "on"). It cuts that ground as soon as the any of the three hvac buttons is pressed, allowing the ecu to control it.

All the air distribution flap positions are controlled by the three hvac buttons via engine intake generated vacuum, no electrics there.

 

Do you have the WSM page number? Is it for Mondial t or?

 

H28 - H37 for the QV.
It seems to me though that the 3.2 and t have a very similar setup.
The driver's side operation is identical.

 

Hi, Mike

The speed fan knob has a fuse. Its located beside the knob. When removing the ash tray and little flap for coins you have access to it.

Guido

 

Mike, I have the same car as you, I'm pretty sure it isn't a fuse, for the fan speed control you need to replace the power transistor (part number 127014, it's $158 at T Rutlands now). I couldn't find any cross reference to the actual transistor part number. Brett at Gran Turismo (aka brettski here) did mine (thanks Brett). As for the hot and cold, there's a valve (don't know the part number), but the rheostat can be tested with an ohmmeter first. I bought the valve on ebay from a car being parted out. It will be installed in the Spring. I have a spare rheostat somewhere but not sure where it is now. I picked up a used one not knowing where the problem was but the problem turned out to be the valve, not the rheostat.

Update: It's 31 Euros from www.eurospares.co.uk

 

Anyone knows what the fuse is protecting in the fan speed knob?

My full speed override isn't always working (as in: almost never) but the microswitch and the relay are OK. Any thoughts? Connector issue? The fuse seems OK on mine, I can see the wire.

 

The power transistor itself is a ~$5 commercially-available item (but you want the 25A kind, not the 15A kind) -- search on part number 2N5886 or NTE181.

 

Thank you!