I have rebuilt a couple Porsche ac systems so I’m not totally clueless but I was wondering if you guys know this? My Mondial T coupe ac works for about 10-15 mins then blows warm air. It has done that for the last three times I have driven it. Is there a pressure switch problem maybe or some sort of temp sensor problem? Thanks Sent from my iPhone using FerrariChat
I would start by checking what's happening at the pressure switch on top of the drier canister (at least that's where it is on a 348). I believe it will shut the system down if the pressure gets too high, or too low. You need to hook up an ohm meter across the contacts of that switch and run the system. There should be no resistance to start with, and then when the system shuts down the question will be is one of the two circuits on the pressure switch suddenly showing no flow of electrons. If so either the switch is bad, or the system pressure too high or low. Put an A/C manifold gauge set on and re-run the experiment and see what the pressures are inside there. Sent from my VS990 using FerrariChat.com mobile app
Can you tell if the compressor clutch is engaging and disengaging on your car? As Paul says, the receiver/dryer pressure switch might be tripping off the compressor, but I'm not sure why it would do it after a relatively fixed time period (10~15 minutes). Similarly, if it was an air temperature sensor problem, you wouldn't expect it to fail after a 10~15 minute time period. Is the temperature change rapid? That is, icy cold one minute, hot the next minute or is it a relatively slow process. Are your fans working?
Ok I will try those things. Thanks for the info guys. Qavion even when it was working correctly there was no real noticeable indication of the compressor kicking on and off. Johnk that’s kind of what I was thinking too.....icing maybe Sent from my iPhone using FerrariChat
Part of the pressure switch, at least on the 348, operates the condenser fan. When the compressed gas reaches certain temperature (and, consequently, pressure) the switch will switch the condenser fan on. If this switch is faulty, the condenser fan will not come on, the cooling will be reduced and the gas pressure will continue climbing which will eventually cause the compressor to be cut out. Have you checked that your condenser fan is operating?
Oooh, that's a good one. Also check there isn't anything blocking air flow to the condenser like leaves or last week's newspaper Sent from my VS990 using FerrariChat.com mobile app
Just throwing this out there... as I recall, on the Mondial the heater control valve defaults to "heat". In other words, if de-energized, the valve is physically open and will allow flow to the heater.
