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Q: Driver side blowing hot air with passenger side blowing cold on 1999 Cadillac DeVille

I have checked each vacuum line and each holds 8" mercury rock solid. all actuator levers working properly. Vacuum from source and vacuum tank working properly. Electric motor on mixing chamber working correctly when cool or hot is selected. Running it threw cycles all functions i.e. defrost, floor vents, dash vents working properly. I have run out of ides, any suggestions would be appreciated.
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Is it blowing hot or warm? These had problems when the refrigerant was low in the system it would blow cold on passenger side and warm on drivers. Recommend have the A/C checked.
Thank you for the info, The charge showed right on the mark between blue ok and green recharge. I will pick up another can of 134a and recharge the system. will let you know the outcome. Thanks again for the direction

Update: I recharged the system, but still the same issue, warm on the drivers side cold on the passenger. Will drop the mixing chamber and see if the flaps are working the way they should via the two electric motor's that drive the internal flapper's

New update: I found the problem!! Someone had installed a new heater core, and in doing so they busted the little black clip that holds the lower control arm to the lower door in the mixing chamber. Needless to say they never fixed that just stuck the housing back together and walked away, so the door never closed on the heater core and was letting in hot air no matter what you were calling for via the controls. A simple fix by installing a new control rod clip, now everything is working perfectly. Thanks
Hey I'm having exact same issue and was the job hard getting to heater core did you have to remove dash or was it accessible threw bottom
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