Lately, the Climate control area makes a hissing noise when the temp wheel is on anything other than max cool, unless on auto - once it reaches selected temp, it stops hissing then, too. My guess is a change over valve or pod. BUT, I also noticed that when vacuum is leaking, the leak slows down and stops under part load/part throttle! Is there a vacuum pump function that slows/stops vacuum under load??? It almost reminds me of how gassers lose vacuum under load.

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Thanks,
Mark in NC

"Spark plugs?...We don't need no stinking spark plugs!"
1985 300SD "Der Silberne Schlitten" 420,000 mi


Wish these were diesel:
2003 Ford Club Wagon 130,000 mi