1970 Charger HVAC questions....

[Kern Dog]

I am nearing completion of several interior upgrades and I'd really like to get the heater and A/C system to work. I've had the Charger since March of 2000 and in all this time, the heater has never worked. I haven't really cared all that much since the car is primarily a 3 season driver anyway.
The car is a 1970 Charger with factory A/C. I'd actually prefer that it were not an A/C setup but it is. The plastic electric/vacuum switch was so stiff, the push button keys barely could move. I replaced the switch while I was doing the wiring changes and the new guage installation. The keys all move freely now. I get no power to the switch though. On the engine side, the fan does not get power either. If I disconnect the wire leading to the fan motor and add a jumper wire to it, the fan will spin. I have a FSM to trace that wire but I was hoping to get some insight as to why the fan may not be getting power if all the wiring associated to it is unmolested. Is there a relay that is troublesome? If so, where is it?
I need to run a vacuum line from the engine to the small storage can for the A/C operation. Is it likely that the electric/vacuum switch needs a vacuum signal to allow the fan to energize? Sorry to sound like an idiot here, I'm trying to learn more about electrical systems and can really benefit from the help!

[cdr]

blown fuse ?

[John_Kunkel]

I get no power to the switch though.

Without power to the switch, nothing HVAC related is gonna work.

[Kern Dog]

I messed around with the car for almost 3 hours yesterday and am happy to report that I DID get the fan to work!
There is a 6 pin male/female connector that leads to the vacuum switch. Only 5 ports are used. I simply pulled the connector apart, blew into both, then snapped it back together. I must have not pushed it together tight enough before when I had the heater/A-C panel out to change the switch.
I did have to pull the ashtray and guage cluster again to get a clear view of it all. The fan works on low and high but only using the A/C buttons. I tried the HEAT and DEF buttons but the fan stopped. I'm thinking that the various vacuum connections redirect the air doors and since I currently have no vacuum hoses attached from the engine to the system, that is my next move. I just bought 43 feet of 7/64" hose and some connectors to replace the brittle sections under the hood.

[Kern Dog]

Hello again...



I finally got the fan to spin for my heater/A-C system after replacing the vacuum switch. Strange thing is, the fan only blows in the A/C and Max A/C settings. The fan stops when I press either the Heat or Defroster buttons. The heater box has never been out of the car but the dash side vacuum lines look fine. I replaced the vacuum lines on the engine side but with no clear listing anywhere of the correct route, I just did what I thought made sense.
From a manifold vacuum port on the carburetor, I ran a line to the small vacuum can. Halfway to the can, the line has a T that allows a separate line pass through the firewall. On the vacuum can, the other nipple has a line that also runs through the firewall with a T that has a line going to a thermo valve on the firewall.
I am totally new to these vacuum/electric type heater systems. I'm confused as to why the fan only works on the A/C function.
Any helpful guidance out there? YouTube was no help!