rcraft Posted October 12, 2018 Share Posted October 12, 2018 Hello Buick Riviera Experts I have been working on my 1964 Buick Riviera Air Conditioner system for sometime now. My current hangup is the vacuum controls meaning the vacuum going to the two diaphragms that open the two doors in the plenum. In particular, although the vacuum strength coming from the engine to the supply line in the dash control area is very strong, the strength of the vacuum at the diaphragm controlling the Heater and Evap. Air Door is very week and won't move that diaphragm. However, if you move the diaphragm arm manually it will stay open and plenty of air is blowing through the dash outlets. Don't know why the vacuum is not strong enough to move that door but is enough to hold it open ??? Any thoughts on this subject ? Additionally but probably unrelated is this fact. My diagram from my service manual page 11-79 shows the white and yellow vacuum lines going to the Heater and Evap. Air Door dual stage diaphragm AND the green and red lines going to the Outside and Recirculated Air Door. It is just the opposite in the actual car. Is this possibly a misprint in the manual ? Thanks to anyone with input. Ray Link to comment Share on other sites More sharing options...
gungeey Posted October 12, 2018 Share Posted October 12, 2018 HI Ray, sounds like you have a pretty good overview of the system. You have strong vacuum from the source (plastic can on passenger fender) to climate controls (center console). Sounds like you have some vacuum loss OUT to the diaphragm. I would plug the line at center console rubber distribution block (square on underside of controls in car)and test for vacuum in the engine compartment. If it don't hold then you have a leak in the line. It's patient work as there are a couple "T's" in there to deal with. Sounds like you have a split in your original hoses...just a guess.. blow some low pressure air from engine compartment you will ear/feel the leak, if that is the problem. Yes you are correct the manual is a little off. Steve You should consider joining the Riviera Owners Association if you haven't yet, there's a forum right here under Buick.. Link to comment Share on other sites More sharing options...
Mssr. Bwatoe Posted October 13, 2018 Share Posted October 13, 2018 Look at the control head, it switches the vacuum..my 64 had issue there, good chance to clean and lube it, and connections Link to comment Share on other sites More sharing options...
rcraft Posted October 14, 2018 Author Share Posted October 14, 2018 By control head you mean the heater/air cond. controls on the center dash I take it, and then do you mean lubricate where the metal parts are of the two adapters for all of the vacuum lines? Link to comment Share on other sites More sharing options...
cheezestaak2000 Posted October 14, 2018 Share Posted October 14, 2018 the best tool for diagnossing vaccum problems on 60's buicks is a small hand opperated vaccum pump. how much are you getting at the main control, how much at the air door diaphram?you can have the answer in a minute or two. also, you can see if any amount of vaccum will even activate those diaphrams. Link to comment Share on other sites More sharing options...
Uncle_Buck Posted October 14, 2018 Share Posted October 14, 2018 (edited) A vacuum gauge, vacuum hoses of various size, hose connectors that step up/down vacuum hose sizes is also handy as you diagnose the system. Often the amount of vacuum at the engine source or vacuum canister is less at the diaphram. The gauge will show what element is leaking. Vacuum hoses tend to split and leak where the are pushed onto a connector. Follow the hoses, take notes and keep the faith. This and other procedures in this thread has led to problem identified, problem solved on my GM cars. Good luck. Edited October 14, 2018 by Uncle_Buck (see edit history) Link to comment Share on other sites More sharing options...
rcraft Posted October 14, 2018 Author Share Posted October 14, 2018 I have a hand operated vacuum pump. I'll have to just keep looking for that little leak somewhere. Thanks Link to comment Share on other sites More sharing options...
Turbinator Posted October 18, 2018 Share Posted October 18, 2018 A suggestion is to inspect your vacuum hoses. Cracks/leaks in vacuum switch hoses to the vacuum actuator can be a problem. Old Air sells a set of the vacuum hoses that are color coded that is right handy when replacing the old hoses. I replaced all my vacuum hoses actuators in my 63 Riviera, hopefully you don't need to do that. Red Riviera Bob Link to comment Share on other sites More sharing options...
mikespeed35 Posted June 17, 2022 Share Posted June 17, 2022 This thread is the exact information I was looking for on my 64. Thanks guys. Sometimes computors can be a blessing! CORDially Mike Link to comment Share on other sites More sharing options...
mikespeed35 Posted June 17, 2022 Share Posted June 17, 2022 It was said earlier in this thread that "the Manual is a little off". Where is it off? I can't check the system if the vaccum lines aren't going as described in the manual. Yellow, White, etc. CORDially Mike Link to comment Share on other sites More sharing options...
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