TTAC commentator Kenzter writes:
I recently picked up a 1969 Cadillac Sedan Deville. It was one of those once-in-a-lifetime deals you only hear about, like my uncles cousins sister is selling her deceased husbands garage queen for pennies on the dollar deal.
My problem is, the Automatic Climate Control (a $550 option!) does not work. The only settings that trigger any response are FOG and ICE. Even then, I can only hear the blower motor and just barely feel air from the floor vents. Where to begin the troubleshooting?
Damn son, that sounds like a choice cut of Cadillac. I love Caddy’s “fuselage era” not just because I bleed Panther Love, or started watching Mad Men from the beginning on DVD last week…but that never hurts!
First off, you told me absolutely nothing about the car’s condition. Odds are older vehicles have worn out HVAC systems because of use or neglect. I hope you understand the headaches associated with old car ownership: when I removed/replaced the evaporator/heater core/blower motor from my 1988 Mercury Cougar XR-7 with nearly 200,000 miles on the clock, I was horrified at the state of everything! But cleaning and replacing worked so well: even with a conversion to less-efficient R134a, the Cougar now has the strongest A/C in the Mehta fleet. It will freeze the balls off a polar bear on the low-speed setting!
Even low mile garage queens have HVAC problems, because getting old is a bitch no matter who or what you are.
That said, my gut says you have bad vacuum lines under the hood. Especially the one from the vacuum source to the firewall, to (eventually) the HVAC box behind the dashboard. But that’s for starters: I am so confident because you said the only “response” was from the defogger setting. Most, if not all, HVAC systems will default to the top setting when vacuum lines fail: this is a safety feature to keep your windshield from fogging up in interior/exterior climate changes. Well, in theory.
But what else do you do? You probably need a new blower motor, at this age. And maybe the factory service manuals (that you need to own) will help you dig deeper and find more problems. Also get Cadillac specific parts catalogs from various vendors, just so you know what the world has to offer in terms of new parts. Every catalog I get in the mail is like a mini-Christmas present…even if I may buy elsewhere, especially via eBay.
When you have the proper books, get the proper tools. Maybe join a local Cadillac-LaSalle club. Start reading up, learning and slowly tackle the project in your spare time. Eventually you will fix the whole system. And enjoy the ride, because everything can and will eventually fail on an antique car. That’s part of the fun.
Welcome to the sickness, I am happy you joined us!
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