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I am right at this point and having a hard time seeing exactly how that diverter door works. When I operate my console wheel from C-H I see a door on the engine bay side opening and closing. Are the interior and exterior doors supposed to be connected and operate at the same time off the same cable ?
thanks
Sorry for the long explanation, but I hope it helps you with your trouble shooting. The doors operate separately and independently.
The cable moves the air diverter inside the heater box. When it is set to "cold", the diverter should block the passage to the heater core. Also there is a shoe where the cable connects to the bracket on the heater box. In the cold position, that shoe should push against a vacuum valve that shuts off the hot water flow to the heater core. The cable only moves the flap inside the heater box. I believe they used a cable because it allows "mixing" air by setting the diverter somewhere between full cold and full hot.
Once the air passes through the heater box, it goes either into the a/c duct system, or the heating/defrost duct system, as determined separately by the system selector. When "Vent" or "A/C" is selected, vacuum is applied to the actuator, pulling the flap back (yellow arrow) and diverting air out of the front of the heater box and into the a/c ducting. When "Heat" or "Defrost" is selected, vacuum is removed and the flap returns to its default position, which allows air to pass on through and into the heat / defrost system. The actuator for the diverter is located opposite the diverter, between the heater box and firewall. It's very difficult to get to without removing the box.
There is a similar actuator on the heater / defrost duct system that diverts air either up through the defrost vent or down through the heater vents. The default position (no vacuum) is through the heater vents. Hope this helps. Good luck.
This should help some. I forgot who supplied this photo about 2 years ago, but I marked it up with where most items are so you get an idea how the air box on an AC Corvette all works. He had his out of his '68 about the time I was trying to figure where I needed to go to fix my lack of heat issue.
Heater cooler (looking from engine side) and heat control door
Heat is controlled with a cable so unless the cable is bad or the door is jammed, there isn't much that can go wrong.
To heater and defroster ducts with the vacuum control. The vacuum control controls air to heater/defroster or to AC. You can see the defroster ducts in my pictures back a few messages. The control for heater or defroster is not shown. If you get nothing to the AC ducts, then the vacuum line to this control may have come off, the control has a leak, or the vacuum switch under the console panel is bad.
To the AC ducts.
Last edited by Procrastination Racing; Mar 21, 2017 at 12:56 AM.
Ok, Just taking a look at it today. Just got it out, "upstate NY". The blower is blowing I can here it well on high. I only get air out of the floor vents. The fan must be on high, any other setting and barely any air flow anywhere. On vent no air, AC or heat. Apparently their are 4 fan switch positions. The only one that does anything is high and like I said only the floor vents.
Thanks, Just got into it today. I'm getting hot air on high. Only through the floor ducts. Any other setting barely blows anything. The blower is running good I can hear it very well. I opened the console up and found the vacuum controlled selector. I had to stop but tomorrow I'm going to run the system and manually try the vacuum controller. It's obvious now that the doors aren't opening for the vents and the defrost. It seems like the fan switch has 4 positions but the only one that does anything is the high setting. More tomorrow.
Ok, Just taking a look at it today. Just got it out, "upstate NY". The blower is blowing I can here it well on high. I only get air out of the floor vents. The fan must be on high, any other setting and barely any air flow anywhere. On vent no air, AC or heat. Apparently their are 4 fan switch positions. The only one that does anything is high and like I said only the floor vents.
Frankenbro,
It sounds like you have two problems. The first is the electrical power to the blower motor. If you look at your control panel, you will not see an "Off" setting for the blower switch. I believe the units always run. Place the speed selector one step below high, if the fan runs on low, then your variable control resistor probably needs replaced or the connection is bad. You can test it and determine if it's bad. It's sticking out of the evaporator box in the engine compartment and looks like this:
The variable resistor reduces the voltage applied to the blower relay. The more resistance across the variable resistor, the lower the relay output and motor speed. When the variable resistor goes out, the maximum resistance is applied so all speeds are low except for the high speed setting, which bypasses the variable resistor and activates the relay coil to switch the output over to direct 12 V power. Since you have high and low, your relay is functioning. The relay is shown below:
The vents are controlled by vacuum. When no vacuum is applied to the a/c actuator and no vacuum is applied to the defrost actuator, air is channeled through the center floor vents. You do not have a bi-level setting, so these actuators are either activated or idle. Since you only get air from the floor vents regardless of control panel settings, the actuators are not getting vacuum. It's likely that you do not have source vacuum or the vacuum switch on the ac panel is not functioning properly. I doubt both actuators would be bad. You could also set the a/c to "Max" and see if the passenger side kick panel flap opens (the cowl flap should close at the same time). If not, you probably have an a/c control panel or vacuum source problem. With a hand pump you could check the control switch function. Hope this helps.
Thanks for the info. You've given me a start. It's an 82 that sat in storage for awhile before I bought it I'm the 2nd owner. The 1st was a woman that knows nothing about cars. She looked good in it. Could be dry rot. It gets warm but the air, hot or cold barely comes out of it. I've never seen so many vacuum lines on a car. I think I'll just start replacing them all. Thanks, That's what I like about this site, there's always someone with an answer. Nobody else wants to listen to us, or they have an expensive fix that doesn't work. Allot of mechanics around here like that. It took me 5 years and about $2000 to find somebody that could figure out it was a just a $50 sensor on the fuel injection.
Should I be able to open that fresh air vent manually? I have the controller switch apart and can hear air flowing and changes when I move the switch. I cannot open that fresh air vent on the passenger side.
I don't believe that a problem with the fresh/recirculate damper could cause a problem with the volume of air flow. In all settings except "MAX A/C" the system uses fresh (outside) air and you should easily hear the inrush of air into the passenger side of the wiper well with the blower at "hi".
The fresh/recirculate vacuum motor--you'll find the vacuum hose leading to it in the passenger foot well--is easy to test for a leak with a hand vacuum pump. Provided it doesn't leak it's also easy to test for function because you'll hear the difference at the passenger side of the wiper well. From what I read here it is though an extreme pain to replace.
Ok, from all of the information gathered on here I believe the vacuum selector switch is part of the problem. I disconnected it from the controller and worked it manually. I was able to get heat and cool air through the dash vents. When it was in the defrost setting I could hear air, so I believe that is a leak, "hopefully." I ordered a new Vacuum selector switch and the blower motor switch that controls fan speed.
I am unable to open that passenger side kick vent manually or otherwise. Does anyone know if this should open manually?
I will be taking that apart in the next few days. I'm hoping the new vacuum switch will solve all of my problems.
Thanks to everyone, you knowledge is invaluable. Frank
Ok, from all of the information gathered on here I believe the vacuum selector switch is part of the problem. I disconnected it from the controller and worked it manually. I was able to get heat and cool air through the dash vents. When it was in the defrost setting I could hear air, so I believe that is a leak, "hopefully." I ordered a new Vacuum selector switch and the blower motor switch that controls fan speed.
I am unable to open that passenger side kick vent manually or otherwise. Does anyone know if this should open manually?
I will be taking that apart in the next few days. I'm hoping the new vacuum switch will solve all of my problems.
Thanks to everyone, you knowledge is invaluable. Frank
Frankenbro,
Your kick panel vent flap may be difficult to move because a spring holds the flap in the closed position when the vacuum is off. If you disconnect the spring, you may be able to move the panel. Just for reference, here's a picture of the assembly showing where the spring is connected. The pins you see at the top and bottom fit into holes in the fiber glass kick panel vent, so there is nothing to seize up there. If you cannot move the panel, then the actuator pivot points may be binding. In this case, you can remove the two bolts holding the actuator bracket to the door pillar and the flap should move. If you don't already know this, the best way to take these out is to pull down on the upper pin with a needle nose and tilt the flap towards the interior, up, and out at the same time. The holes in the vent are easy to damage, so be careful. Good luck.
Thanks everyone for the information. I replace the vacuum operated switch. Also found that the floor vent door was frozen shut. I took it out cleaned it up and lubed it up. Everything is working fine.
Isn't it awesome to get something extremely annoying like that fixed? I know on my 79 I had to replace the vacuum switch to get it to change where the air comes out. In my case, I could hear a vacuum leak at all times from behind the dash when the car was running.
I will add though, that I recently did the C4 blower motor conversion many have talked about here on my 79. It made a very noticeable difference in the amount of air coming out of the wherever the selector is set.
