Posted by Wally Plumley If you have good vacuum here, remove the console side panel next to the driver's thigh. Inside, find a bundle of small colored plastic lines. Follow those to the vacuum solenoid rack, and with the engine running, use a piece of plastic or rubber tubing stuck in your best ear to listen for a vacuum leak hiss. If you have good vacuum (no hissing), cut the orange line, and test the upper end to see if it will hold vacuum. If not, leave it disconnected and plug the other end (that runs forward to the vacuum solenoids) until you decide to replace the center vent comb flap actuator . If the upper section holds vacuum, connect the cut ends with a piece of small tubing. (If you remove the vacuum solenoid rack - which isn't too easy - you can do the testing there, instead of cutting lines.) Test the functioning of the system. If it works, great! If not, repeat the test (cut the line, test the upper end) on the blue, yellow and green lines. Don't cut the black line - that is the source. Don't cut the white line - that is the coolant valve, and it needs to work. The valve is under the air cleaner on the back of the engine. Send me an email if you want a paper that describes the 928 HVAC system - no cost. Wally Plumley
on 7/12/2007, 2:54 pm, in reply to "no vacuum to climate controls..."
208.61.124.129
Find the vacuum brake booster under the hood. On the top of the booster, there will be a small vacuum line coming off of the valve. A few inches down the line is a small black & blue one-way check valve. With the engine running see if you have good vacuum at the outlet of the check valve. If not, test the check valve. If so, carefully check the four-way rubber connector for leaks.
928 Specialists
http://www.928gt.com
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