Diagnosing a HVAC vacuum issue on a Ford F53
The AC/heat is switching to the defroster under higher RPM conditions on my 2006 F53 chassis Damon. It actually seems to be doing it now under low throttle steady state conditions as well. Obviously...
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The leads me to focus on the vacuum accumulator but I'm not sure how to test it. I can't even figure out how to remove the lines going in and out and I don't want to break anything fumbling around. Any suggestions?
As was posted, using an accelerant next to the vacuum hoses is an old school diagnostic technique. I've used ether (starting fluid) for this as I usually have a can of it in the shop.
