F40 air conditioning wiring diagram required.

Dig back into the 308/328 wiring diagrams.they should be very clos, or at least point you in a direction.

 

The A/C / Heating control system on an F40 is nothing like a 308/328. It has an ECU that looks at an in-car temp sensor (on the panel behind the headliner) and the requested temperature control signal and then either engages the A/C compressor clutch or cycles the electric heater valve on/off. The ECU on an F40 is the same part as a Testarossa/512TR/512M, so the wiring diagram from any of those cars should guide you in the right direction. It is a very simple system.

 

Like I said, the Testarossa wiring diagrams from the same time period will have the correct wiring connections at the climate control ECU as the F40 (since they use the same ECU)
The ECU is a plastic rectangular box on the backside of the passenger footplate with two separate electrical connectors on it. I have never seen one go bad. It is basically separated into two parts. The A/C portion looks at the input from the temp control knob and a temp sensor inside the evaporator housing and then cycles the compressor on/off depending on the inputs. The heater portion looks at the in-car temp sensor (the little plastic dome in the headliner panel behind the seats, a heater temp sensor in the housing and the temp control knob input and powers the heater valve closed (which is just an electro-magnet with a plunger valve). For more heat it cycles the valve on/off. At either end of the temp control the valve will be fully powered closed or no power (open). You can check power at the valve connector with a 12v injector noid light. There is a main power bosch type relay in the fusebox that supplies power to the system. Have you checked the refrigerant charge in the system? The main reason that the compressor clutch might not have power is that low freon charge causes the low pressure switch on the receiver-drier to open.

 

Like the mans says, try shorting the wires on the pressure switch fitted to the drier, if not try disconnecting the wire- if i remember correctly with the mondial you should hear the compressor clutch engaging/ disengaging - you need the ignition on but not the engine running. If that works then the pressure switch is no good or you have lost the gas- this protects the compressor from running with no gas.
If you get it working, put your hand on both pipes on the drier, they should both be cool but if the outlet is colder than the inlet then the drier is getting blocked- this has the effect of the liquid freon expanding over the blockage and causing the drop in temperature- this liquid expansion normally occurs over the expansion valve prior to the evaporator in the car.

 

Try the wires on the pressure switch on the drier as i had to replace mine as it was stopping the compressor clutch engaging

 

Sweet! Easy "fixes" are the best.

I didn't even know F40s had AC - lol

 

Didja know the F40's had a heated windshield?

 

Hi all

I wonder if anyone here knows enough about the F40 A/C system to help try get mine working ?

The compressor clutch does engage but the air doesn't get very cold at all, feeling the hoses in and out of the dryer, tx valve or condensor they don't seem hot cold or any different, I have tested all the sensors on the ac control module plug and they are all close to each other in temp going off the resistance chart I have, hot cold knob resistance is ok.

Where should I look next ?

..and are the 2 Schrader valves on the 90 degree fittings screwed into the pump the only fill/hi low ports ?

 

Find a tech that can check the freon level. Probably low on freon.
Yes, the two ports on the compressor are the only ports on that system.

 

I put my gauges on it this afternoon and you might be right, low side was only ~20psi with engine off and went to zero when running, no pressure high side.

Will vac and refill and see, anyone know how much gas it takes ?

 

Ok takes 1.1Kg... its in the owners manual

Does anyone know how the engine fans are triggered by the AC ?

Are they supposed to run with AC ?