328 Air-Conditioning Problem

It sounds like the expansion valve is freezing up. When it freezes, you'll suddenly get warm air b/c the flow of R12 suddenly stops. Also, the pressure sensor in the system will shut down the compressor to keep from damaging it.

I believe replacement of the valve is the only fix but others may have a few other solutions to try before that step.

 

Do you mean no air flow at the vents at all? or air flow at the vents but not cool air?

 

I've experienced your issue twice in my 348. Really, really cold air, then it goes hot. Turn off the A/C for 5 seconds, turn it back on, and then it works just fine.

Makes me think that I've got a compressor relay or compressor clutch that got stuck. Besides those two times, my issue hasn't reappeared for weeks (of daily use, too).

But, here's something that you can test. There are two pipes going in/out of the evaporator/dryer. One is (fat?) *low side* and one is (thin?) *high side* Touch the low side; it should be cold. The high side should be hot. If not, then you have a compressor/leak/refrigerant problem. If they're the right temps, then you've got a problem in the dash, the blend door, air/water in a line, or maybe your heater core.
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Cool post ND

You are correct about the pipe sizes too Ideally you should try that temp test off the compressor pipes IMO

 

great post, except if his temps are correct to touch, does that mean no leak? He said he got 'cold' one time.

If the latter, what in his dash would make something cold once then not the next: thermostat/switch? that's my guess.


Couldn't he trigger the thermo to, say, stay on always? My Mondial T [much like the 348] has crappy climate control switches.....there was a link on such earlier I'll try to find it.

 

Hey, I'm just some Joe wrenching on his own Ferrari...I don't really *know*, but...I do wonder if a faulty interior temp sensor could cause the temp to swing wildly (especially in my 348).

Thermostat/switch? Sure. Very possible, too.

 

Sure, it's possible...but have you done the high-side/low-side touch test yet?

You're going to have to start doing some tests to narrow down your problem rather than just guess.

 

Thanks again for the insight. I'm adding a picture of mine. It is located under the front carpet. Easy to get at but be care full not to break the carpet backer. My low side port was very cold so I must have an issue that is causing the heater to come on sometimes. It doesn't always kick on, and sometime I can toggle between setting and get the AC working with the heater off, but sometimes not. I'll report back if I find the gremlin. Image Unavailable, Please Login

 

Having had a 328 for almost 20 years the AC in the car is not that great, however if properly working it will keep you cool when you are moving. It sound like the Condenser is freezing up and stopping... I would check a couple of things - most likely you will need a pro AC tech / Ferrari mechanic:

1. check or leaks - also know if its R-12 or 134.... if its been converted, but lines have not been swapped, my bet is you are running low on refrigerant... the car was designed for R-12 - and 134 simply does not stay in the system as long... the hoses need to be specific to 134.
2. Compressor - high and low sides are located in the engine compartment - on the passenger side next to the camshaft... very easy to get gauges on there and check... also run a leak detector in there.
3. check for dripping or condensation under the fuse panel ... that can tell you if its freezing up
4. In the front boot - remove the hard-liners behind the spare tire - and check that the expansion valve is covered in cork tape - note if you by cork tape from an automotive store it's expensive - for very little - but if you by HO railroad self-adhesive road bed - its the same stuff its like 1000th the price.

lastly the thermostat control - the one with the blue and white plate... could be bad... unlikely but possible - these are hard to find... As always check fuses and connectors as well they can get corroded.

best of luck - I know its frustrating. I Used Freeze 12 in my system with good results - but had to top it up 2-3 times a summer. Living in Atlanta having AC is a need vs. comfort...

 

Make sure the ground on the dipstick tube mount is tight. Make sure the compressor is getting battery voltage with the a/C on..if it is..Make sure the compressor clutch is operating. Be sure the system is fully charged.

 

The sensor/switch number 9 has probably failed. This measures the line temperature at the condensor, and actuates the condensor fan as required, typically cycling on and off at less than highway speeds.

If it is not working, the fan will not go on and off when required, the system will overheat and over presuure, and the system will protect itself and the compressor clutch will be cut off. Once the pressures and temp go back down, it will work again, then the problem will recur.

The sensor used to be unavailable, I think they are now reproduced and the cost is ok. You can actually bypass the switch by a wire jumper, but the fan will run all the time when the compressor is on. Worth doing this jumper before replacing the sensor, if the jumped sensor and fan always on results in consistent cooling, then the sensor is the problem. Won't hurt anything to have the fan always on, but long term this would shorten the fan motor life, and waste energy.