ATC

[jmustian]

Well its me again. Before i dig into the FSM, does anyone have ideas on ATC units.
When i had the heater core out i made sure the box was clean and all the doors and vacuum valves worked correctly. I bought a new 5 button control unit and replaced the fan motor. Now im just getting around to the ATC and dont have any idea why the fan wont come on. I dont hear the doors moving either so thats probably a vacuum problem.

 

[The_Eagles’_Nest]

What year car is this again? It is my understanding that 1970 and older Auto-Temp systems have virtually no parts availability and are way less reliable than the 1971 and newer systems.

Make sure your controls are getting 12v in, and that your grounds are good.
Make sure you have 12v on the car side of the connector to the blower motor. Check the basics.

 

[jmustian]

What year car is this again? It is my understanding that 1970 and older Auto-Temp systems have virtually no parts availability and are way less reliable than the 1971 and newer systems.

Make sure your controls are getting 12v in, and that your grounds are good.
Make sure you have 12v on the car side of the connector to the blower motor. Check the basics.

1969 chrysler 300. New switch and new blower. Gonna start back tr the basics. Got good ground and need to recheck vacuum to the switch. The switch is both vacuum and electric. My biggest concern is that temperature wheel. Im not familiar how that works.

 

[The_Eagles’_Nest]

The temperature wheel is likely a rheostat type device that would change the signal to the amplifier that sends a signal to the servo, at least that’s what Auto-Temp II does.

 

[jmustian]

Ill recheck the basics and then get out the manual. Never been great with electrics haha

 

[The_Eagles’_Nest]

FSM says it is the same as a home thermostat, so it must be a potentiometer then actually. I highly recommend you read the FSM. It will tell you exactly how things work.

 

[marko]

not sure if this applies in this case, but when i bring my 78 Salon ( with ATC II) out of storage, the blower doesnt come on until vacuum has built up in the system, usually after the car has been running for about 20-25 mins.......

 

[The_Eagles’_Nest]

not sure if this applies in this case, but when i bring my 78 Salon ( with ATC II) out of storage, the blower doesnt come on until vacuum has built up in the system, usually after the car has been running for about 20-25 mins.......

The cold engine lock-out prevents the blower from running when the coolant is less than 125°F.

 

[marko]

The cold engine lock-out prevents the blower from running when the coolant is less than 125°F.

tx, never thought of that, took it for granted it was a vacuum switch related.
but it doesnt take take 20 mins for my car to get to operating temp tho

 

[The_Eagles’_Nest]

Then you may have a different concern that needs to be diagnosed.

 

[MOVE N UP]

Entering the 9 circles of hell... trying to resurrect my ATC... update IT LIVES!

This master switch was one of the culprits of my non functioning system-but as soon as I replaced it -my blower fan would operate.

 

[jmustian]

All this is a little beyond my abilities but im gonna dive in anyway. The ac compressor is empty and unplugged also so i got a long road haha.

 

[The_Eagles’_Nest]

All this is a little beyond my abilities but im gonna dive in anyway. The ac compressor is empty and unplugged also so i got a long road haha.

These cars are complex for their time. They are simple compared to anything built in the last 10 years.

Take photos, that your time, and read the manual. Think of each step on its own and complete everything as if each component is its own concern. Don’t think of it as the A/C system needing an overhaul, think of the blower motor, the servo, the amplifier, etc.

I work on Lincolns, anything from a Corsair to a Navigator and these old Chrysler products are easy compared to that.

 

[rags]

I work on Lincolns, anything from a Corsair to a Navigator and these old Chrysler products are easy compared to that.

so then, never any CAN communications issues with replacement modules in ATC systems? they don't have to be flashed with manufacturer proprietary scan tools? just diagnosed with a vacuum gauge and test light? whoa!

 

[The_Eagles’_Nest]

so then, never any CAN communications issues with replacement modules in ATC systems? they don't have to be flashed with manufacturer proprietary scan tools? just diagnosed with a vacuum gauge and test light? whoa!

Nope! Modern cars are infinitely better and more reliable than any 50 year old dinosaur (he said sarcastically).

 

[commando1]

Nope! Modern cars are infinitely better and more reliable than any 50 year old dinosaur (he said sarcastically).

I don't care. I still buy the 10 year extended warranty.

 

[The_Eagles’_Nest]

I don't care. I still buy the 10 year extended warranty.

I would, but after working on modern cars I would never buy one.

 

[thethee]

tx, never thought of that, took it for granted it was a vacuum switch related.
but it doesnt take take 20 mins for my car to get to operating temp tho

I'm 90 percent sure you have a vacuum leak somewhere

 

[thethee]

All this is a little beyond my abilities but im gonna dive in anyway. The ac compressor is empty and unplugged also so i got a long road haha.

In this case the FSM is your friend. There should be a service diagnosis schematic or list in the "heat and a/c" chapter. Looks like this in mine:

Don't expect it to give you the exact solution but it's a good starting point.

 

[marko]

I'm 90 percent sure you have a vacuum leak somewhere

thats what i figured, but the car has to sit 4-5 months for the vacuum before this happens, once its being used its fine. i have a feeling its leaking somewhere along the automatic brake lines