fil756

mosty 986 and 996 shop manuals - electical diagrams - and Porsche PET parts catalog CHECK IT OUT http://www.cannell.co.uk/Manuals.htm

loren is right. the best way to flush the system is with the right equipment but there is a way to do it without. There is actually a bleeder valve under the black cover that surrounds the oil fill neck and the top of the coolant reservoir. i flushed my 98 boxster a while ago for 30k service and ill try to remember as accurately as i can what i did... so here goes take off the oil fil cap and coolant cap and pry up the black plastic piece that sits at the bottom it should come out with a little work. under the plastic is a round black plastic thing with a metal clip on top. pull up on the metal clip and it will release the trapped air in the coolant system. you will have to fill and pull it repeating this several times to alow the air to escape for enough room to add coolant. when the coolant level doesnt go down anymore cap off the oil and coolant reservoir and go for a test drive. as you drive it will cause more air bubbles to surface and thus turns on your coolant light on the dash. stop fill and bleed the system a couple times. BE CAREFUL the coolant will be hot and under pressure. bleed it slowly before removing the cap. fill it up and keep driving. this will probably happen several times before the light will not come on anymore. when you think you got all the air out make sure to top off the coolant reservoir. i would recommend using porsche coolant. it is formulated for porsche engines and the metals and alloys in them. i think the coolant is about $40 a gallon. but you will mix it half and half with water. i would also recommend using distilled water to reduce deposits from forming in the system due to calcium and other sediments. after all it is a porsche and it should be treated like one. let me know if you need any more help phil

It sounds like the pressure your reading (100psi) is probably the static pressure. static pressure is the pressure read when the compressor is off and both low and high sides are equalized. depending on ambient air temp that sounds like a good static pressure so i dont think that your system needs to be charged. sounds to me like the compressor isnt running. you should notice a click sound when the compressor engages(at least on most cars). sense porsche engines are well hidden its probably hard to hear. if your compressor is running and your pressure on the low side is 100psi you either have a bad compressor (not compressing) or maybe a restriction (somewhere between the service fitting and compressor) restrictions are most common at the oriface or expansion valve. im unfamiliar with porsches a/c system and its hard to diagnose without the high side pressure. 35-45 psi is about right for the low side the high side should be about 200 psi both when the compressor is running. pressures are relative to ambient air temp as well as condenser and evaporator efficiency. there are other factors that effect pressures too like air flow but that is roughly what they should be. anyway thats a lot of info but if i was you i would double check to see if your compressor is running. hope that helps phil