Heater INOP. Fan INOP. A/C INOP.

[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!

 

[miller]

Think I recall seeing your photos of that switch, in your other post.

Not positive, but don't think the switch works unless it's on any setting besides 'off'. Need to check if there's connection between the two connectors on the switch itself, and of course, if it is getting power. Pretty sure the fan doesn't get power, until the switch is on a heat, or cool setting...nothing at 'off'.

My switch is kinda like your's. Had to rebuild it, getting some of the 50 year stuff off of it. Contacts inside could be corroded.

 

[Kern Dog]

I am happy to report that I did somehow get the blower to work.
I hesitate to take any credit for this success. I was frustrated with it and I was getting nowhere for three hours. I checked connections, scraped and cleaned them and even soldered wires to a spare switch and still I had nothing. Fuse was good.

The wires leading to the blower resistor consist of a 3 wire plug and a separate single spade connector. The 3 wire plug only had one terminal with power, the others had nothing. I backtraced the wiring from the blower motor, through the bulkhead and into a group of wires. Two of them went through the vacuum switch. The connector has 6 terminals, 5 of which are in use. I merely unplugged the connector, blew air at the ends and plugged it back together. The fan works! I got it to work in both speeds, though there is a dead space between high and low. The air only blows with the A/C buttons pushed, not with the heater or defroster. I am such a newbie to this stuff but I'm curious if the they will work once I connect a vacuum source to the system.

This is the heater switch I have in there now. The old one had stiff buttons and I just didn't trust it.

 

[miller]

Don't know all that much about the heater/AC stuff. But, pretty sure the switches, resistors work together, but only in certain positions...lol, if that makes any sense.

Could be something still in the vacuum switch, keeping it from changing over to heat, or something down the line. If you have a wiring diagram, you say one terminal not working? Trace it out, to see where it goes. Might give you a clue on it.

Mine's a non AC, but I opened my switch up. Those melted down tabs that hold it together...I cut those off flush, to get inside. I drilled small pilot holes into the remains of the pegs that line it all up. Then used small screws to tap into the pegs, that I used in place of the melted down ends. Makes it so you can get into the switch, deal with it, and close it back up.

 

[Kern Dog]

Don't know much? me either! I'm learning as I go. At 50 years of age, I am pretty good at a few things but I have much to learn about air conditioning, the workings of an automatic transmission and most electrical things.

 

[miller]

Ha! 67, and still learning. Or just getting by.

 

[mopar 3 B]

check the blower motor resistor located on the top of the heater/ac box. All fan switch current flows threw it to the heater fan.