348 Air Conditioner Condenser fan not working

The fuse gets power from the relay, but do you mean power going to pin 30 of the relay or to pin 86 (coil)? Power to pin 30 comes directly from the battery bus bar (behind the footwell relay panel, I think, on the 348). Power going to the coil comes via the pressure switches which, I assume are near the receiver/dryer. If your gas pressure is ok and the switches work (you can jump them if in doubt), you could look further upstream to the compressor relay (in the frunk).

Does your AC work?

 

Diagram here should help your tech:

https://www.dropbox.com/t/Q1SLtqmZ3zjf8T7W

 

If the AC is working, I suspect one of the contacts in the pressure switch is faulty. Try jumping pins 1 & 2 on the pressure switch. Pin 1 is the blue/white wire. Pin 2 is one of the green ones (doesn’t matter which). On the pressure switch side of the plug, it’s the equivalent of shorting the two (unstriped) blue wires together.

Maybe hit the switch with a large hammer first

 

The condenser fan does not always run while the compressor is on. The fan is switched on and off by the refrigerant pressure via the "high" pair of contacts in the pressure switch. It actually goes by the refrigerant temperature - higher temp causes higher pressure which triggers the switch for the fan to cool the refrigerant down, then the switch goes off and the cycle continues. While driving, the fan may stay off all the time. When stationary and testing the AC in somewhat cold weather, it may take some time for the fan to come "on".

 

That is, if you can't put enough demand on the aircon system to trip the switch (as Miro says), short these two blue wires.

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If you can't backprobe the connector (to short the wires), unplug the connector and do it on the car side of the connector. The AC won't work, but the fan should.

 

Got a question for you guys. I have a 1994 348 spider, i bought a new 134a ac compressor and filter dryer for it. The filter dryer is the identical one to the original except the pressure switch port is female not male. The pressure switch is female. I found a 2 wire pressure switch that threads in and is o-ring bossed for proper sealing. Using the original switch with an adapter I made by rethreading a 1/8"npt to 1/8" flare on one side and a 1/4" flare (I think) on the other side with shrader valve, is less than ideal as there really isn't a place for the o-ring to seal on the adapter. I'd have to braise a brass washer or something on it, which i am not set up to do. Using this 2 wire switch wouldb so much better if possible.
If I tie the blue/white wire to the green black wire so that when power comes into the switch through the green wire and comes out on both blue white and green black to turn on the ac clutch and the condensor fan at the same time. Condenser fan will run all the time but every car I've ever worked on in 25 years has the condensor fan run constantly when ac is enabled.

Is there any harm in running the condensor fan the entire time the ac clutch is engaged?

I realize the head pressure will be lower due to the condensor constantly cooling the high side but will it be too low to function?

This cross posted to another thread here in ferrari chat just for anyone who that matters to.

 

Diagram for reference:



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So you're saying the compressor circuit is identical, but there is no fan switch, so you have to jump the green wire and the blue/white wire?

 

The simplest solution is to buy a 4-wire pressure switch with a male thread and o-ring on it. You can find one if you google; example: New Hi and Low Trinary Pressure Switch Kit

 

I have done this on my 348 but I have a modified compressor control using the classic capillary thermostat switch that will cycle the compressor and the condenser fan at the same time (like in the old days). Does the factory AC system cycle the compressor or keeps it running all the time like some cars do? With the condenser fan running every time the compressor is on, I actually got better cooling when stationary and no issues at all. While I still had the pressure switch controlling the condenser fan, I found (in tropical climate, Malaysia) that the fan was coming on a bit too late to maintain good cooling - I could feel the air blow inside the cabin getting a bit warmer (due to the condenser getting rather hot) before the condenser fan came on.

If the factory AC system cycles the compressor, then the only disadvantage I can think of in having the condenser fan run every time the compressor is on is higher wear of the fan. The fan will also (unnecessarily) run when moving at higher speeds but then the air pushed through the scoop will help turning the fan and greatly reduce its current draw; and it is also possible that the air flow (at, say, 200+ Km/h) will start turning the fan like a turbine causing it to become a generator and supply free wind power to the car's "grid".

 

Thank you so much, I found a couple that would work

sunair mc-1412 has the exact brass adapter with o-ring boss needed to use the four seasons brand filter dryer with the oem ferrari trinary switch.

Or if you want to not use an adapter fitting, santech part number mt1459 from autozone will screw right in and even has spade connectors on the end of the wires that could be depinned out of the connector and pinned into the stock ferrari connector (probably), otherwise just crimp on the ferrari connector using butt connectors. Amazon also has trinary switches for $16 that need to crimped to the ferrari connector with whatever method you choose.

Since i already have the 2 pin low pressure switch, I depinned the harness side connector and used a piggy back spade connector to connect blue/white and green/black to one side of the switch and green to the other side. No cutting involved and can be put back to original at any point. The oem connector is still attached to the green jumper wire that jumps pin 2 and 3 so that i will never lose the connector if i want to revert back to oem with either the proper brass adapter and oem ferrari trinary switch or a new male threaded trinary switch and some male spade connectors to pin in the oem ferrari trinary switch side connector.