Started by scotth3886, November 28, 2021, 02:51:11 AM
Quote from: cadillactim on November 28, 2021, 08:55:51 PMVery common issue. The problem is vacuum leaks. In the settings other than Defrost there is too much vacuum leaking off to overcome the spring pressure in the master vacuum switch. Once that spring pressure has been overcome there is barely enough vacuum to keep it closed when the lever is moved back to Automatic. But once the vacuum leaks more (like under acceleration), the switch shuts back off.Most common area of vacuum leaks are the rotary valves in the power servo. But there could be other leaks elsewhere.Tim
Quote from: Larry Savino on November 29, 2021, 06:01:56 AMAlthough I cant answer your question.and I don't have a Classic Cadillac yet (I am searching for a 1965 thru 1968 convertible) I did find a guy who sells manuals year specific to diagnose these complicated HVAC systems . I think I paid 49.00 plus shipping I can post he contact info if you would likegood Luck I had a 67 Deville in the 90's and I was always chasing gremlins out of the HVAC system
Quote from: cadillactim on November 29, 2021, 07:15:35 AMYes, I sell rebuilt power servos. You can reach me directly at 864-348-7732, or email me at email@example.com for more information.Tim
Quote from: cadillactim on November 29, 2021, 08:23:36 PMPinch off the vacuum lines coming from the intake manifold, including the one to the brake booster. If engine smooths out, then trace vacuum leak. If engine still runs rough, spray some carb cleaner around the intake and see if idle improves. If it does you may have a cracked intake manifold.Tim
Quote from: JV3RI on November 29, 2021, 07:37:12 PMand my other project ...... finding and replacing every inch of vacuum hose in my 66 Brougham. Got the manual from Cadillac Tim - thanks Tim. Got all the hoses changed - even the hoses and accuators behind the kick panels, under the carpet, in the door panels, under the dash, under the hood. That got the power door locks working again. It also helped smooth out the idle. Everything was working and the idle and acceleration were great. Then, just a few days later - with all that brand new rubber hose everywhere - the engine starts running extremely rough. So rough that the restoration shop refuses to start it again for fear of really damaging something. All this vacuum work was done this year - and last year we hauled the engine out and did a full top to bottom rebuild. Not sure what to do next - call the Exorcist ??
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