Trying to get the heater working

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sargentrs

sargentrs

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'74 Dart, 225 /6, A904, Factory heat/AC. Fall's coming and starting to get cool so I need to get my heater working. Pick up the grandkids from the babysitter every evening and can't let the little one's be cold now can I? PO says the heater core's been replaced and with the condition of all the heater/AC stuff I'm inclined to believe him. Here's what I know:

Blower motor in engine compartment firewall is not factory and not plugged in. Squeals loudly when power applied. Probably has wrong fan cage. Can't find the plug in the harness.
Hoses in the engine compartment look recently replaced but are not connected and water pump is bypassed.
No control valve in heater hose.
Driver's defrost hose is connected, passenger's was in the trunk.
Switch/selector appears intact although connections are questionable.
There's a few wires under/inside the dash that are not connected.
Dash pad is not bolted down and easily removed.
Vacuum pot on driver's side of the AC is loosely attached. Small panel it attaches too appears to be floating around? Does the pot attach to a small panel and then the panel attaches to the case?

I've studied the manual and have an idea of which way to go but I have a couple of questions.

What does the blower motor plug look like? Is it just 2 straight spades parallel to each other or at right angles to one another. The latter is hanging loose in the dash.
The control valve does go in the inlet hose in the engine compartment and not in the interior somewhere, right? And it's a vacuum operated, normally open, valve?
Anybody got pics of the AC/heater box so I'll know what's connected or not connected or missing? Especially the back side. I shouldn't have to remove the box to hook up everything should I?
Anybody have an exploded view of the whole assembly? My manuals scan are pretty dark and can't see much detail in the pics.
Any and all input, advice or pics are greatly appreciated!
 
Very first question is, "do you have" a factory service manual? If not you should get one. We don't have a 74 to download, but there IS a 73, in the bottom end of this thread: http://www.forabodiesonly.com/mopar/showthread.php?p=1970088617

Now, there were SOME wiring changes from 73 to 74, but most of it is the same If you get into the section on heaters / AC there's procedures in there to check the vacuum on the switch, etc and routing diagrams to show how the vacuum / doors work.

In the back of section 8, 73 was a HUGE change in how wiring was drawn. There's an index behind the diagrams to locate connectors Start on page 8-152 and notice the contents there, "connector charts."

Just below that, in the alpha index, find "Air conditioning blower motor, at D-36. Go to D-36. Make sure you are looking at the AC blower, not the heater blower. Notice the circled "CE-20" This means "connector, engine, no 20"

Now go to page 8-164. This is the start of the connector pictorials. Find "CE-20" This is simply a single wire booted plug, dark green. The wire no. on the diagram is C5-14DGN for "Dark GreeN"

Notice this is IN the engine bay, not under the dash
 
NOTE. Just checked my 74 manual. The connector reference was changed, but it is basically the same. In that diagram, they add the idea that the DGN blower wire comes out of a firewall grommet with ONE other wire, a dark blue going to the "engine harness disconnect." This is an in harness connector, usually white, connecting up the engine section
 
Thanks 67dart273! I have that '73 manual you spoke of, printed out the section you mentioned, and have it handy when I get started troubleshooting. And thanks for the tutorial on how to read that connector reference. I was confused on that. Should I have a vacuum reservoir on the inner fender? I don't. The PO hacked up so much stuff on this car I'm repeatedly finding things missing, incorrectly installed or just plain jury rigged.
 
I always have to go through the vacuum and switch stuff "step by step." Best advice I can offer is to read the manual, section on AC. Buried in there, somewhere, is diagrams and descriptions of the switch functions in various switch positions.

You should not need the vacuum can to get it working, but you DO need whatever hose that leads to the interior, hooked to manifold vacuum, or the doors will never position correctly
 
Hey sargentrs:

Pictures say a thousand words, so here are a few that should get your heater up and running-

First one is the connection for the blower motor. It's the single green wire. There is a connecter inline as shown, then the green wire enters the wiring harness that runs across the firewall. You have the blower than can be removed easily so just pull the 4 nuts and it comes out. I've encountered some that needed cleaned and lubed up, then worked fine. Otherwise you can replace it with the right one.



Next is the heater valve and the vacuum reservoir. The valve on my Dart is the original style which you cannot get from a parts store any longer. O'Reilly has a replacement that looks different but should work fine. About $14. Notice the vacuum line connected to it.

Then there is the vacuum tank. The picture shows 1 line connected to it. There are supposed to be 2 lines. The one at the top which I have unhooked goes to the intake(engine vacuum)



Now a look at those two small vacuum lines. One leads to the heater valve, the other to the vacuum tank. The vacuum tank adds capacity so that the system doesn't switch functions under acceleration. Vacuum goes from the tank into the car where the selector panel redistributes it. One line comes back out to operate the heater valve. Here are the two lines where they enter the firewall. Notice one has a green stripe. That goes to the heater valve.



Now a look at the heater hose connections at the firewall:

The outer hose, toward the fender is the outlet. On a slant it leads to the connection on the cylinder head next to the thermostat. The other hose is the inlet and goes through the heater valve and then to the connection on the water pump.



Lastly, the dashpot on the heater box:

As you can see it just bolts on with two bolts and has a hose with a yellow stripe on it.



Let us know if you need more help.
 
Very Nice! Tyler That ought to get him in the neighborhood. And I'll add that the heater cotrol valve is in the normally off position if that wasn't covered yet, as well as those old blower motors squall like crazy when the bushings in the motor get dryed up of lube. The end the squirrel cage is on can be gotten to easily with a little oil, but the back bushing is inside the motor case. If you drill a small hole in that hump on the back of the motor, (1/32 or so) that cavity is where the end of the amature shaft and bearing are and you can put a few drops in there for the back bushing. Afterwards a small dab of black RTV can serve to seal it back up so dust doesn't get in there.
 
Thanks guys!
TrailBeast said:
And I'll add that the heater control valve is in the normally off position
Click to expand...
Do you mean that with the selector switch in the off position, the valve is closed so that no water flows into the core?
TylerW said:
Lastly, the dashpot on the heater box: As you can see it just bolts on with two bolts and has a hose with a yellow stripe on it.
Click to expand...
That picture helps a lot. On mine, the pot's bracket is screwed into that panel but that panel is floating around loosely in the case. Is that side of the case another piece that's screwed in? Like TylerW said, a picture is worth a thousand words. Here's a pic of the engine compartment with the areas in TylerW's pics. You can see my consternation when comparing them. Don't know what the blower motor came off of but it has 2 parallel spade terminals and looks fairly new. If works but sounds like the wheel is trapped, squealing loudly. I'll know more when I get it out. And, as you can see, the vacuum lines in the firewall are missing. That line you see coming out of the hole is a Sunpro aftermarket temp gauge I installed until I can get all the gauges working. I found a bunch of stuff in the trunk including a rats nest of vacuum lines, 2 vacuum amplifiers, an exhaust manifold, old EGR valve, etc. This is typical of the sins of the PO that I've encountered since I got the car. I'm sure, when I get to it, the switches, vacuum lines, cables and such on the interior will be the same.
 

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sargentrs said:
Thanks guys! Do you mean that with the selector switch in the off position, the valve is closed so that no water flows into the core?
Click to expand...
Yes, it blocks the flow into the core in the off position, and the same without vacuum connected to the valve. It takes a vac source to open it. That doesn't mean the hoses and core don't have coolant in them though, just that hot coolant can't be circulated through the core and produce heat inside the car.
 
Thanks for the clarification TrailBeast! Ok, good news, bad news. Found the blower motor plug and it appears that the selector works. I have power in all 3 speeds. Pulled the blower motor and figured out that reason it was squealing was because the blower wheel was too close to the firewall so it was binding. Scooted it out on the shaft about an 1/8" and no more squeal. From the motor part number it appears to be from a newer Grand Cherokee. Made up a couple of wires and connected one terminal to the harness plug and grounded the other terminal to the firewall. Now the blower works on all 3 speeds. Now the bad news. The air appears to be going nowhere. Can't feel it from the a/c vents, the defrost vents or anywhere around the case. Speaking of which, where does the heater blow out to? Couldn't see any vents pointing toward the floor. Best I can tell, the dampers must all be in the closed position so vacuum is not being applied to the appropriate places. Pulled the glove box and removed the dash pad so I could see what was going on and found out there was only one vacuum line connected on the selector, one vacant and one broken. Are there only 3? Across the top of the heater box were 3 lines but the solid black one was not connected to anything. Also the one that went to the vacuum pot I questioned was there going off to the left. The selector has the cable connected securely and appears to be functioning. Also investigated that vacuum pot on the driver's side and the case is definitely busted. Can I get replace that vacuum connector on the selector or do I have to buy another selector? The way it's broken off, I can't even plug it to continue testing. I guess I'll see if I can glue that vacuum pot panel back in place. Advice, opinions, thoughts? On a side note, any idea what the 2 prong plug in the last photo might go to? It's just hanging down in front of the heater box.
 

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That plug you found is for one of those PITA buzzers. Can't remember right off if it's seat belt or key in the ignition. Which one of yours ain't working? In any case you can tape that one up and tuck it back up under the dash...
 
Ok... are you sure the fan is running the right direction? The original had one terminal so it was impossible to wire it backwards but since that one has two, then it's possible. Even if the HVAC has no vacuum, it will default to the defroster and heater normally.

Next, in the photo of the tan part of the selector:

There are only two hoses. You are missing one, the rear one. On my car, the front port(toward the trunk) has a green hose. When I say green I mean black with green stripe and that will apply from here on.

The rear port has a white vacuum hose. The green one leads out to the water valve, the white leads around to connect to the other vacuum lines.

Speaking of which-

There is supposed to be way more than just two vacuum lines connected to the selector. There is also a vacuum "harness" that has a molded end that fits onto another part of the selector. Take a look at the selector in this link and you will see what I mean in the 4th picture.

[ame="http://www.ebay.com/itm/1973-1974-1975-1976-DART-DUSTER-A-AC-HEATER-CONTROL-ASSEMBLY-PLYMOUTH-DODGE-/271463542929?pt=Vintage_Car_Truck_Parts_Accessories&hash=item3f347cf091&vxp=mtr"]1973 1974 1975 1976 Dart Duster A AC Heater Control Assembly Plymouth Dodge | eBay[/ame]

The vacuum dashpot that is broken off the side of the box is the defroster actuator.

My guess is the PO did all that damage when removing the heater box to replace the core. You should go back and ask him to refund some money for the aggravation. The Factory Service manual shows exactly how to remove the heater core without pulling the entire box.

I have the vacuum diagram for the heat/air if you need me to scan it.
 
sargentrs said:
None are working. Ha! Hate those things. Thanks grumpus!
Click to expand...

The buzzer itself is high up on the driver side kick panel behind the fusebox. It has two horizontal terminals spaced widely apart. You should plug it back in temporarily and get an earful of that thing.
 
Really? That plug was all the over hanging under the dash at the glove box. Gotta love what them PO's do1
 
Thanks again, TylerW! I guess I'll have to pull the selector after all, so I can get a good look at it. There were no other lines coming out of it. So, the line that is in place should be the one that goes to the water valve, right? The one that's missing goes to the other, multiple port, connector that I haven't seen yet? As mentioned before, in the trunk, was a wad of vacuum lines and there was a molded connector connected to several of them. I'll dig that out of the basement and see. I've seen pics on Google and looked at that Ebay listing after our prior conversation. I'm assuming that the 5 ports in a diamond on the right are the one's that the molded connector plugs in, one of the other two is one from the other 2 port connector, with the white stripe, and the last one is the source from the reservoir/intake?
 
I'll get the page out of the fsm scanned and posted for you. If that wad of lines are all striped with colors, that's the one you are looking for. They probably removed it, couldn't figure out how it went back on(admittedly it isn't easy) and said the hell with it.
 
I have the diagrams from the '73 FSM that shows the functions of the selector switch, the associated vacuum lines and which one's are "on" with which function, if that's the one you're talking about? On the blower motor rotation direction, I'll double check that this afternoon. Thanks for all your help!
 

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Yes, that's it. Here is the section dealing with the water valve operation in case you don't have that part. The vacuum transfer switch should be that part on the passenger side of the control with 2 ports. Green toward the rear of the car and white on the other port.
 
Thanks TylerW! Got that printed out and handy. I did find that mass of vacuum lines and it is the plug for the back of the selector, same pattern of ports. Time to plug it in and start checking vacuum!
 
P.S. I did have blower wired backward. Swapped the wires and I now have air flow.#-o
 
Funny how these things work out. You started out wanting a working heater and you may have solved the same problem for a bunch of people. We now know that a blower motor from a Jeep Grand Cherokee will work in an A body. They are a lot easier to find and will be around for a lot of years. Which wire did you ground to get the right rotation? Well done sergeant...
 
Well, I feel better now. After sucking all the info I can out of you guys, I get to give something back. With the motor installed in the firewall, the driver's side terminal goes to the dark green wire in the harness and the passenger grounds to a convenient place on the firewall. The motor is a Denso AY166100-0402. It's just screwed in with some self tapping sheet metal screws. The wheel was a tight fit through the whole and the PO might have enlarged it a hair from the looks if it. Not a perfect fit but workable.
 
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