Unfortunately, my 300K still has a later-year 383 CID engine with a two-barrel carb. However, it has a large steel fitting screwed into the back of the intake manifold. The fitting has a barb on top and the vacuum hose for the power brake booster is plugged into the barb. There is a small side outlet from the fitting. The ¼” hose to the heater control switch vacuum connection fits onto this side outlet and goes through a grommet in the firewall to the switch behind the dash. The two ¼” vacuum lines to the door actuator “motor” on the underhood side of the heater box also are routed through this dame grommet. A friend with the single four-barrel 360 HP engine indicates this is the situation on his engine, also. One of the rams for my 390 HP engine is also set up for a similar fitting.
Did I see that you are able to rebuild the heater control switches? The only problem with mine is the stiff push-buttons/ sticky sliding plates. Before I do something stupid, can you (or anyone else) comment on the potential effectiveness or dangers of slugging the switch internals with WD-40, brake cleaner, silicone lube or similar solvent/lube to loosen up and re-lubing the slides while not dissolving or weakening the plastic switch? This might eliminate the need to disassemble the switch.
From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of Harry Torgeson torg66@xxxxxxxxx [Chrysler300]
Sent: Saturday, November 19, 2016 10:42 AM
To: John Grady <jkg@xxxxxxxxxxxxxxxxx>
Cc: Rich Barber <c300@xxxxxxx>; Chrysler 300 List <Chrysler300@xxxxxxxxxxxxxxx>
Subject: Re: [Chrysler300] Servo
Thanks for the help, my buttons are hard to push, so I might have to rebuild or replace the switch, but I will check the vacuum connection at the motor first, does anyone no where it is?
On Sat, Nov 19, 2016 at 3:59 AM, John Grady <jkg@xxxxxxxxxxxxxxxxx> wrote:
I should have added that JY Chouinard found an excellent explanation of vacuum tube routing and function ( impossible to find in FSM') in I think 59 Imperial FSM , he uploaded that with very valuable added info I think via Bob Merrit to site tech info . I have no experience with 59 cars but am told they use this system , first year . If you note in the referenced later FSM 's , nothing at all in there about the vacuum system logic . JY 's diagram ID each port correlated with which button is in and hose stripe colors .
Sent from my iPhone
O&M instructions for the air distribution controls system are found in the service manual on pages 24-23 to 24-25. http://www.jholst.net/64-service-manual/air-conditioning.pdf The three dampers or baffles are called “doors” and are opened and closed by vacuum. The vacuum distribution system center is a white plastic block on the back of the heater-A/C control module. (Fig. 28-control switch). Pushing each of the five control buttons switches the vacuum to one side or the other of the diaphragm in the three metal vacuum chambers that actuate the doors. There are seven rubber hoses bound together in a connector that plugs on to the back of the white plastic control switch. One of the hoses is connected to engine vacuum and the other six hoses go to each side of the three actuator cans. One to open and another to close that door. The white plastic control box has seven tiny plastic nipples projecting from its back, over which the seven-hose connector fits. These nipples are pretty delicate and may have been broken off by a previous mechanic. If this is happened you might find a real clever way to repair a broken nipple, but you are more likely going to need to go shopping for a replacement control switch. The white plastic control switch, itself, can be removed and replaced. Wires to the blower and A/C compressor clutch are also fastened to the control switch and pushing the various buttons will also control the A/C clutch.
With the engine running, pressing each of the five buttons on the HVAC control module should cause the various doors to open and close. The blower is controlled by pulling out or pushing in the temperature control lever. With A/C you should have three fan speeds. If pressing the five buttons does not actuate any of the doors you may have inadequate manifold vacuum or a cracked or disconnected vacuum hose that provides source vacuum to the white control block. One of the actuators can be viewed by removing the outside cowl fresh air inlet cover. Another actuator is mounted to outside top of the heater box under the hood and the third is mounted inside and under the dash. You can view the opening and closing of several of these door actuators fairly easily.
The five buttons on my control module require a pretty stiff push to go all the way in and cause the doors to open and close. Anyone been successful at lubing these plastic parts for easier & smoother action? I don’t want to dissolve the plastic block or gum up what I assume are sliding plates inside the block.
Good luck. Heater-Defrost, at least, season is upon us.
Brentwood, CA (43F @ midnight—finally had to turn the furnace on--only pushbuttons are on the digital thermostat)
I have a 1964 300K, my sero vacuum system for heater AC does not work, does anyone know how to fix it and know were its located?
Posted by: "Rich Barber" <c300@xxxxxxx>
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