ATC workaround

The benefit of running a Dodge Dealership is that I can search parts over the entire continent. Found several Dealers in the USA still showing inventory.....

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Thanks for your help sir you have been exceedingly helpful. :thumbsup:
 
@Dobalovr I've been made aware that there might be more differences in the wiring between '75 Imp and '76-'78 NY than I thought. While I'm still pretty certain the high blower motor relay should be on that relay bank and yours is missing, you should really double check with the appropriate FSM to verify that.
 
Well sometimes the simplest answer is the correct one and I wish I could have taken credit for this one. Larry's ATC system is now fully functioning and blowing nice cold air once again. The fix you ask?......

The water control valve was seized. Larry picked up a NOS unit from Epay and after it was installed the ATC II came to life. Fan works in all positions heat and AC work life is good again!

Special Thank you to @thethee for all the assistance and despite his great advice stupidity won the day afterall....
 
The water valve was seized and that caused the fan to remain off? Never would have guessed that. The inner workings of the ATC still elude me..

Or perhaps the seized valve caused the cold engine lockout to remain engaged, who knows. Glad it's fixed though!
 
thethee said:
perhaps the seized valve caused the cold engine lockout to remain engaged
Click to expand...
This ^^ makes the most sense to me as nothing else was touched. Recharged the AC and all was working as it should after the valve replacement. Dumb luck more than skilled repair I am afraid.
 
bigmoparjeff said:
You did a better job of studying the diagram than I did. I missed the water valve on there.

You don't actually "pull the dash" on a formal, as the dash frame is welded to the body. You should have good access to most of what you need to get to by removing the dash pad, which is pretty easy. In most respects, dash related work is much easier on a formal than the earlier cars. I pulled the entire ATC vacuum harness out of our '78 NYB way back when I was 17 or 18 years old, and I don't remember having any difficulties getting to anything once the pad was off.

Jeff
Click to expand...
My 69 300 the whole dash frame had to come out. Only 4 screws and two bolts and a thousand things hooked to it.
 
thethee said:
Okay guys, I have decided that I'm going to work on my ATC system and thought it would be best to start a thread for questions along the way.

My plan is to convert the system to a manual or as much as possible, I'll see how far I'll come.

Before anyone tries to discourage me, right now the ATC is dead, I only have a blower that can be pointed at the defrost outlet and the dash outlet. So basically it can't be any worse and any improvement is a bonus. I'm pretty sure the A/C has lost all refrigerant and I doubt there is still any oil in the RV2 compressor, but it's not seized. I have disconnected it just to be safe. The manual controls were installed when I got the car. After searching the internet and studying the FSM I concluded that I should be able to create a workaround with the ATC box.

First step, the water valve in the engine compartment, or better yet lack thereof. The original valve would have a cold engine lockout switch but for manual a simple vacuum closing water valve would suffice. I'm looking at this one, anyone have any experience with it?
Click to expand...
My AT1 controller is dead according to the c4064 tester. Nothing works. New switches and still no fan on any setting. Does anyone know if I can just run some wires from fan to push button switch. I really just need at least defrost. The red hose to the water valve never gets vacuum from the controller to open. The AC compressor works fine when switching the buttons but still no NEW fan turning on. I think the controller operates that also.
 
thethee said:
The water valve was seized and that caused the fan to remain off? Never would have guessed that. The inner workings of the ATC still elude me..

Or perhaps the seized valve caused the cold engine lockout to remain engaged, who knows. Glad it's fixed though!
Click to expand...
Cold engine lockout for sure.
 
jmustian said:
I added direct vacuum to the water valve and heat is in the car. Just no fan. New fan but need to get back inside wheel well and check fan resistor.
Click to expand...
The fan is actuated by vacuum switches on 74-78 ATC II cars. In my experience the resistor rarely goes bad. If the fan is not coming on the issue is often that power is not getting to the fan through the vacuum switch...again the issues is -you guessed it!- vacuum.

Find the vacuum switch and ensure it is still good (not leaking) and try running separate vacuum to it...I bet the fan springs to life.

So now that you are "fooling the system" anyway by running your own vacuum lines, you may consider running one to the switch to make it run and get you by.

You still will not have control over fan speed though...that can only be achieved by hacking into wiring and installing fan control switches etc.
 
Mr C said:
The fan is actuated by vacuum switches on 74-78 ATC II cars. In my experience the resistor rarely goes bad. If the fan is not coming on the issue is often that power is not getting to the fan through the vacuum switch...again the issues is -you guessed it!- vacuum.

Find the vacuum switch and ensure it is still good (not leaking) and try running separate vacuum to it...I bet the fan springs to life.

So now that you are "fooling the system" anyway by running your own vacuum lines, you may consider running one to the switch to make it run and get you by.

You still will not have control over fan speed though...that can only be achieved by hacking into wiring and installing fan control switches etc.
Click to expand...
Thanks. I found plenty vacuum but somewhere the whole system has no power. Nothing to the controller, nothing to the switches.
 
3175375 said:
You might be able to make an easy fix in getting power where it belongs. Keep on it!
Click to expand...
Main controller burnt out and an electric vacuum module in the controller was burnt too. Maybe why I had to replace some wires.
I'm hooking up a two speed switch to the two wires coming from controller as they feed the fan just fine. Got my heat doors set for defrost only until spring, then I can turn heat off and AC on haha. Always a way except took a week of digging.
 
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