On a somewhat related topic, Deoxit also works great to free-up sticky door lock mechanisms too. - Dave
UPDATE: I had 2 of these modules (3 total if you count the driver side that was working). The car came with a spare used module. Neither of these 2 for the passenger side worked. We used the DeoxIT D5 on both. One still had no function. The other came back to life. So, its worth a try. I saved about 3 grand.
Looking back at Post #4 it might be possible to resolder contacts inside the switch. I dont have any experience with these switches but might be worth a try considering the scarcity. Glad the deoxit worked out, as they say, "I put that stuff on everything" - switches, plugs / connections, grounding points, relay connections, etc.
My drivers side heater control with one red light lit, fails to power the motorized heater valve under the front hood. I’m not sure whether it’s the switch or the heater valve motor. I’m going out to my mechanics today with the car for new brake line installation and will investigate it with multimeter, etc.
I would guess its the switch. I doubt there is feedback back to the switch about the actual position of the valve opening. To me the microswitches get dirty or worn. Unless its completely dead its probably not the circuit board inside the switch. Just guessing but this is 1980's tech stuff. Not very sophisticated.
Today we investigated the heater valve situation, Good News And Bad News. The Good News: The heater valve motor had very dirty electrical plug connections. Deoxide D5 cleaned it rightup. The motor immediately started working and the switch lights illuminated. Success ! The Bad News: As soon as the valve opened up, the valve began to leak I began reading old threads here and found that the part is no longer available from Ferrari, but Maranello Concessionary has a alternative part for approx $500 Another poster here on Ferrari chat mentioned that his heater valve only leaked when opened ALL the way up. If you stop before fully opened, the valve doesn’t leak. We pressurized the system To test and it turned out to be true. So, stop before all the top heater light is illuminated and you’re ok for now. I also played around with the switch and found the first heater light staying illuminated was sporadic. Mostly stays on, but sometimes goes out after using the heating system for a bit and then turning it all off. It usually lights back up though. Image Unavailable, Please Login Image Unavailable, Please Login
I live in Florida, and seldom if ever use the heater, so this was a solution to a slightly leaking valve on my 3.2 Mondial, probably would have been better to replace the valve but I just had a major service done and didn't want to tear into the engine compartment again, it works for me! Alden Image Unavailable, Please Login Image Unavailable, Please Login
4 Seasons is a major supplier of HVAC parts for cars. I just spent 3 or 4 minutes flipping through their heater valve selection and saw several that looked like they would be as easy to convert a 328 to as the one offered by Maranello Classics. They were under $50.
I dont think we need to resort to anything so limited in function. The world is full of cheap readily available heater valves that we can actually adjust
Someone bought the available heater valve from Eurospares and found it to not work like the oem version
I am sure it requires some level of conversion. But for $400 I can do a lot of fabrication to make a generic valve work. I still think the best plan is to see if the originals can be fixed
To add a data point to this discussion: here is an image of a 328 heater valve from a dismantled UK car with part number (Bosch?) visible (0928400017); I presume the “549” is an inspection stamp Image Unavailable, Please Login
Here you find how to open and repair a heater valve= #10 https://www.ferrarichat.com/forum/threads/heater-valve.601331/#post-148778025
Bosch 0928400627 appears to mount the same but is fuel regukatore valve Did they select an odd product to re-purpose? LOL https://www.amazon.com/Pressure-Regulator-Valve-0928400627-0928400617/dp/B07VQKRTXS
The ac/ heater control centre console switches for sale on eBay at moment, haven’t seen any pop up for years in UK if anyone interested plus they other switches against seller https://www.ebay.co.uk/itm/257107238504