First.... Happy Easter!
To use the same “bucket and lid” would make sense.
Good to know the vacuum motors was e also used by gm.
Do you have a source we could put here for the repops? It would be great to have that info here.
What I learned about 74-78 ATC II
- Thread starter 73 T&C
- Start date
To use the same “bucket and lid” would make sense.
Good to know the vacuum motors was e also used by gm.
Do you have a source we could put here for the repops? It would be great to have that info here.
commando1
Old Man with a Hat
Arggghhhh..... That box is currently being stored at Cantflip's abode so I can't get the p/n off the actuator.
Look at the numbers on the actuator and Google them. They pop right up.
Will do Monday!
I can look later...
commando1
Old Man with a Hat
Javier can look on his which are right in front of him.
Nothing came up under this number.
It may be the supplier model number. Linden.
It may be the supplier model number. Linden.
commando1
Old Man with a Hat
Grrrrr...
Jeff?
Sorry... I'll catch it in the daylight tomorrow.
Looks like I found where the screws go for the lid that we’re missing from my salvaged a/c air box.....
on On Stan’s thread about swapping ATC II for standard A/C.
Makes me think the evap may be a replacement.
on On Stan’s thread about swapping ATC II for standard A/C.
Makes me think the evap may be a replacement.
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I am apparently still unable to operate a digital camera... I could get the screen perfect, but the results always sucked...IDK... all I found on a total of 6 of these was those same numbers Javier found.
this EB motor is very similar... it has the nipples on both sides of the diaphragm.
NOS Mopar 1962-65 Chrysler, Dodge, Imperial Heater Vacuum Actuator Valve | eBay
my search brought these caddy ones that look close, but wouldn't work
1959 1960 1961 1962 Cadillac Vacuum Actuator Single with Wire REPRODUCTION Free Shipping in the USA - Cadillac Parts Online
Old Air Products 1959-62 Cadillac Vacuum Actuator - Dual Port with Wire @ OPGI.com
These have promise... with some minor rod creation...
Old Air Products 1970-72 Chevelle Vacuum Actuator, Air Conditioning Dual Port @ OPGI.com
Old Air Products 1970-72 Chevelle Vacuum Actuator, Air Conditioning Dual Port (Defrost) @ OPGI.com
Sorry... can't post their pictures...
commando1
Old Man with a Hat
It has every reason to work, but until the stroke of the motor is verified, IDK if it will do the job.
commando1
Old Man with a Hat
What does that have to do with it???
Full movement of the crank arm
commando1
Old Man with a Hat
Ooh. I thought he was talking about the engine.
Someday you'll have to explain the recent signature... You often leave me in the dust, it's kinda nice to be in front once in a while. I even tried reading the silly mess backwards...
Part 4
The parts under the hood
Unlike it’s predecessor system in the 69 to 73 version of this system, the later version of the AutoTemp II for 64 to 78 has only the vacuum canister, water heater valve, system lockout switch, assorted vacuum and electrical lines and blower fan on the engine side of the fire wall.
I figured I’d start with a view of a very low miles 78 New Yorker Brougham engine bay.
This is what it looked like when it was new.
Here’s a view of my slightly higher miles ‘78 after a bit of work in getting my system back up and running.
In this picture, you see that most of the engine bay ATC II systems resides on the passenger fender. The red circle shows the location of the heater valve and temperature lockout switch as well as the vacuum canister. The arrow shows the approximate location of the engine manifold vacuum connector under the air cleaner.
This is the vacuum “tree” mounted to the engine intake manifold.(carb removed for clarity) The line running to the left from the bottom is the vacuum line for the ATC and connects directly to the vacuum canister on the passenger side fender.
The vacuum canister is basically a coffee can with two connectors and a back flow check valve to keep the vacuum intact and available for use to run the ATC II. The black source line from the engine connects to the check valve on the edge of the check valve. The purple line is the source for vacuum to the ATC system and is connected in the center. The reason for this canister is to maintain a constant vacuum level available to the AutoTemp II despite the engines’ variability to create manifold vacuum (drops in engine manifold vacuum under load). It’s function is a lot like the brake booster in the cars’ power brakes system. Critical here is that the check valve is good and all vacuum lines and connectors are not leaking in any way.
Ok... why three lines to the water heater valve? Because it’s actually two parts. The heater valve and the temperature lockout switch. The tan line to the diaphram is the line that activates (closes) the valve. The other two lines connect to the temperature lockout switch. Of upmost importance is that a vacuum leak at the lockout switch will disable the system.
Between the two is a rubber gasket to create a vacuum chamber for the switch to work. Because if it’s position in the engine compartment, the valve and switch are subject to the radiant heat off the exhaust manifold as well as the coolant flow through the valve.
The job of the lockout switch is to prevent operation of the ATC from starting prior to the coolant temperature reaching at least 125 degrees when the ATC is in heat mode. See FSM.
The parts under the hood
Unlike it’s predecessor system in the 69 to 73 version of this system, the later version of the AutoTemp II for 64 to 78 has only the vacuum canister, water heater valve, system lockout switch, assorted vacuum and electrical lines and blower fan on the engine side of the fire wall.
I figured I’d start with a view of a very low miles 78 New Yorker Brougham engine bay.
In this picture, you see that most of the engine bay ATC II systems resides on the passenger fender. The red circle shows the location of the heater valve and temperature lockout switch as well as the vacuum canister. The arrow shows the approximate location of the engine manifold vacuum connector under the air cleaner.
Ok... why three lines to the water heater valve? Because it’s actually two parts. The heater valve and the temperature lockout switch. The tan line to the diaphram is the line that activates (closes) the valve. The other two lines connect to the temperature lockout switch. Of upmost importance is that a vacuum leak at the lockout switch will disable the system.
Between the two is a rubber gasket to create a vacuum chamber for the switch to work. Because if it’s position in the engine compartment, the valve and switch are subject to the radiant heat off the exhaust manifold as well as the coolant flow through the valve.
The job of the lockout switch is to prevent operation of the ATC from starting prior to the coolant temperature reaching at least 125 degrees when the ATC is in heat mode. See FSM.
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Repair and Troubleshooting the AutoTemp II
This section is meant to help you get the ATC system back up and running. It is not meant as a repair manual for your A/C system or engine repair. It is assumed you have a working compressor and a/c system capable of moving heat and that your engine is in fairly good tune and still able to produce the proper manifold vacuum. If not....start with that and come back here when your done.
But first....
Before you start digging into the system or go crazy looking at the diagnosis matrix.....
Start with the simple stuff first.
1)Make sure all your fuses are up and energized. Voltage should be 13.5volts more or less 1/2 volt.
2)Confirm engine is producing enough steady vacuum for the system to operate correctly. Typical engine vacuum is 16” at idle and fairly steady.
3) Verify the a/c compressor is working and that it is properly charged and that the a/c system is able to properly coil pulling the evaporator.
4) If a lack of heat is the problem, check that hot water is actually getting past the valve to the heater core. Is the heater valve plugged or stuck shut?
Just these four issues above will resolve most of the typical problems associated with the system. Most of the diagnosis charts end in or have one of the above as a possible failure point. So why not start with those.
As we continue you’ll see why.
“My system is not working at all and I checked all the above.....”
Vacuum and electricity make the system work. Vacuum drives the damper door motors and activates the switches that actually turn the system on. Electricity drives the blower fan and compressor clutch. Both of these last two go through the ATC to make them work
Let’s start with starting.... the engine.
In a normally operating system when you start the engine, it takes about three to four seconds for engine vacuum to build in the accumulator and through the control panel with enough force to get to and activate the master switch and compressor switch. (Refer to previous sections for location on the left side on top of the airbox).
Here are what the two switches look like. The green is the master power switch and the yellow is for energizing the compressor clutch. This is the goal for checking vacuum. You can either start checking the vacuum here and if good check for power at one of the connectors to the green vacuum switch. That’s the one that makes the clicking sound a few seconds after you start the car. If that didn’t happen, you need to back up and look for a lot as from the beginning.
A quick way to see if you have enough vacuum going to the system is to pull the purple vacuum line of the accumulator (black coffee can mounted on the passenger side wheel cover) to check for a good vacuum to the system.
Put a vacuum gauge on the nipple that fed the purple line and with the engine running, take a reading.
Here we can see only about 10” of vacuum. That’s a problem. Next, with the gauge still connected, turn engine off and look at the gauge. If it doesn’t drop,then the check valve of the accumulator is good. If not, you have another problem. You can either replace the accumulator and check valve or simply install a check valve in line with the black rubber source line. Check again and if it holds, your good. If not, your coffee can has a leak or the seal holding the check valve is leaking. But, you get the picture.... it has to hold vacuum.
It also needs to be enough vacuum. So, assuming you’ve got and can hold vacuum up to now, it needs to be more than the 10” I just read. Let’s start with the source at the vacuum takeoff from the manifold and make sure we have the correct vacuum there and that the line from there to the accumulator is tight and not kinked or pinched.
The line running to the left from the bottom of the “tree” is the ATC line to the accumulator. The rest are manifold vacuum for the brakes and other sensors/accessories. Make sure these are tight as well before testing and that any leaks are also taken care of. Disconnecting and testing from here will check to make sure that the engine is producing the required vacuum.
“I have vacuum going to and from the accumulator.... Now what????”
Well, as long as we’re in the engine compartment, there’s one more thing to check.
The heater valve has several vacuum connectors of which the two lines ( green and orange) connect to a thermal valve that keeps the Autotemp II from coming on until engine temperature reaches at least 125 degrees.... but not only when your asking for heat. Even when asking for A/C, that vacuum switch needs to be air tight. If not th system will not come on.
This is the heater valve. Just below the vacuum motor of the heater valve, is the switch which is held to the heater valve by two small Phillips head screws. Between the valve and the switch is a rectangular rubber seal. At this stage, that seal has been through countless heating and cooling cycles and as much as 45 years. You may want to change it or at least remember that this is critical to getting the Auto temp to come on.
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DIAGNOSTIC cont. (2)
Ok, so I checked all the connections in the front and they are good.... also checked the power to the main switch under the dash, but still no action from the system. What now?
Up to now we’ve been working with pretty basic tools. A multimeter and a hand vacuum pump and gauge. As we will be looking at multiple vacuum connections going on from here, you may want to buy or borrow a decent vacuum pump with a regulator instead of the one that came with the car ..... the engine. I would recommend a small electric one to keep from having to start the car every time you want to run a check for vacuum to a specific location. It will also allow you to listen for leaks better.
Using your hand held vacuum pump and guage, check first that the master switch (the green one) is good. Disconnect the electrical and vacuum connector and then connect the vacuum pump to the switch and see if it holds vacuum. If it does, apply something more than 10” or vacuum to it and with your multimeter check that there is continuity through that switch when vacuum is applied.
If no continuity is present, this week s you problem.
As a check, start the car and set it to high auto and jump the circuit. (here you can sit the key to run and also connect your vacuum pump to the accumulator and place a battery charger on the battery rather than starting the engine) If the system comes on you have found your problem. If you have continuity, and the switch is good, you may also have a vacuum loss to the switch keeping the system from coming on. With the engine running, or a vacuum pump set to 16” connected to the acumulator, check the vacuum reaching the master switch. If less than 10” of vacuum is reaching the master switch you have a loss somewhere in the network of lines.
Time for some tedious work.
Up to now, we’ve not had to take too much apart to do the initial checking of the system above. Going forward we will have to start take parts off and out for access. You can get to almost the entire system by removing the lower under dash vents and the dash cover
Check the vacuum motors which operate the defrost and direction doors first. Both motors have two vacuum lines to them to allow the system to pwe them in two directions. Simply disconnect one little me at a time to determine each motors ability to hold vacuum in both directions. DONT DISCONNECT MORE THAN ONE LINE AT A TIME. Otherwise, you will get to spend a good deal of time sorting the lines with the FSM diagrams. While your doing this, check the rubber boots at the end of the lines are properly connected and tight. The colored lines were originally glued in to the rubber boots but 40 years and other people working on electrical repairs or previous attempts at repair to the system that may have damaged them.
(Insert picture of rubber boots at end of colored vacuum lines.)
My system still isn’t coming on after doing all the above.....twice
If your getting power to and through the master switch, then you have a problem with the switch connectors or switches at the control panel.
You will need to remove the front trim of the dash panel off at this stage.
Pull the control panel out and check the connections for power, continuity to the amplifier and from the amplifier to the servo using the wiring diagram.
I have power to the control panel but only the defrost is working.
Ok, if you are only getting the defrost to work, congratulations!!!!! Defrost is an outlier setting in that it does not go through the amplifier or servo to operate. Your amplifier may be burned out. But before you go nuts, first check that it’s getting power and that the connector is properly seated.
Located on the right side of the passenger footwell, check the connection to power and proper seating of the multi plug connector.
If no problem with power to the amplifier, check the sensor circuit for 5.4v from the wiring diagram. If no output power is coming from the amplifier, then replace the amplifier.
Ok, I replaced the amplifier and the blower is working now but now I only get cold air/hot air from the system.
You probably have a problem with the sensors they are either not completely connected, shorted out or loose. The temp set bar on the control panel, the interior ambient sensor and the external ambient temp sensor are all connected in series.
If you’re getting full cold air from the upper vents in the dash, one or more of these are shorted out and offering no resistance. This is rare... more commonly.....
If your getting nothing but heat from the lower vents, one or more of the the sensors or temperature set is not making a good connection and is creating an opening in the circuit.
Time to take the dash cover off now....
Using the descriptions of each in the FSM (page 24-118), check each for complete connections and each for their proper component resistance. See also the relevant sections of this thread for location and description of each of the above.
Remove and replace any defective part and test it again.
Ok, so I checked all the connections in the front and they are good.... also checked the power to the main switch under the dash, but still no action from the system. What now?
Up to now we’ve been working with pretty basic tools. A multimeter and a hand vacuum pump and gauge. As we will be looking at multiple vacuum connections going on from here, you may want to buy or borrow a decent vacuum pump with a regulator instead of the one that came with the car ..... the engine. I would recommend a small electric one to keep from having to start the car every time you want to run a check for vacuum to a specific location. It will also allow you to listen for leaks better.
Using your hand held vacuum pump and guage, check first that the master switch (the green one) is good. Disconnect the electrical and vacuum connector and then connect the vacuum pump to the switch and see if it holds vacuum. If it does, apply something more than 10” or vacuum to it and with your multimeter check that there is continuity through that switch when vacuum is applied.
If no continuity is present, this week s you problem.
As a check, start the car and set it to high auto and jump the circuit. (here you can sit the key to run and also connect your vacuum pump to the accumulator and place a battery charger on the battery rather than starting the engine) If the system comes on you have found your problem. If you have continuity, and the switch is good, you may also have a vacuum loss to the switch keeping the system from coming on. With the engine running, or a vacuum pump set to 16” connected to the acumulator, check the vacuum reaching the master switch. If less than 10” of vacuum is reaching the master switch you have a loss somewhere in the network of lines.
Time for some tedious work.
Up to now, we’ve not had to take too much apart to do the initial checking of the system above. Going forward we will have to start take parts off and out for access. You can get to almost the entire system by removing the lower under dash vents and the dash cover
Check the vacuum motors which operate the defrost and direction doors first. Both motors have two vacuum lines to them to allow the system to pwe them in two directions. Simply disconnect one little me at a time to determine each motors ability to hold vacuum in both directions. DONT DISCONNECT MORE THAN ONE LINE AT A TIME. Otherwise, you will get to spend a good deal of time sorting the lines with the FSM diagrams. While your doing this, check the rubber boots at the end of the lines are properly connected and tight. The colored lines were originally glued in to the rubber boots but 40 years and other people working on electrical repairs or previous attempts at repair to the system that may have damaged them.
(Insert picture of rubber boots at end of colored vacuum lines.)
My system still isn’t coming on after doing all the above.....twice
If your getting power to and through the master switch, then you have a problem with the switch connectors or switches at the control panel.
You will need to remove the front trim of the dash panel off at this stage.
Pull the control panel out and check the connections for power, continuity to the amplifier and from the amplifier to the servo using the wiring diagram.
I have power to the control panel but only the defrost is working.
Ok, if you are only getting the defrost to work, congratulations!!!!! Defrost is an outlier setting in that it does not go through the amplifier or servo to operate. Your amplifier may be burned out. But before you go nuts, first check that it’s getting power and that the connector is properly seated.
Located on the right side of the passenger footwell, check the connection to power and proper seating of the multi plug connector.
If no problem with power to the amplifier, check the sensor circuit for 5.4v from the wiring diagram. If no output power is coming from the amplifier, then replace the amplifier.
Ok, I replaced the amplifier and the blower is working now but now I only get cold air/hot air from the system.
You probably have a problem with the sensors they are either not completely connected, shorted out or loose. The temp set bar on the control panel, the interior ambient sensor and the external ambient temp sensor are all connected in series.
If you’re getting full cold air from the upper vents in the dash, one or more of these are shorted out and offering no resistance. This is rare... more commonly.....
If your getting nothing but heat from the lower vents, one or more of the the sensors or temperature set is not making a good connection and is creating an opening in the circuit.
Time to take the dash cover off now....
Using the descriptions of each in the FSM (page 24-118), check each for complete connections and each for their proper component resistance. See also the relevant sections of this thread for location and description of each of the above.
Remove and replace any defective part and test it again.
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DIAGNOSTIC cont. (3)
My A/C works well but never puts out really cold air. What is that all about?
The AutoTemp II is a chill/reheat system. This means that all the air being conditioned is first run through the evaporator and then none, all or a part of it is run through the heater core and directed either to the upper or lower vents. Unless the outside temp is less than about 40 degrees, and the system is set for anything but OFF or VENT, the compressor is running all the time in this system. Likewise, the heater valve will be full open.
If you think that the system is not making cold enough air, you may have one (or more) of the following issues:
(With the upper dash removed for access and, of course, assuming that the system is capable of making air cold through the evaporate down to between 35 and 45 degrees).....
1) One or more of the ambient temp sensors is off spec. Not very likely.... if you got this far. But, if you haven’t checked them up to now, check them all now in accordance with specs outlined in the FSM on page 24-118.
2) Blend door in the airbox is not set correctly at the servo. Adjustment of the link needs to be made so that, at the 65 degree setting on the control panel, the servo actuates the blend door to full open with no or very little blend air. (Typical for these systems after 40+ years)
This is the link that needs to be adjusted. This link is described as “self adjusting” in that, once adjusted, it will self-locate the blend door to the full closed position against the heater core chamber whenever the servo moves to full cold.
To adjust, you need to shorten the distance between the end of the looped hard wire and the curled spring steel link. Thumb on the loop end and index and middle fingers on the spring clip ,(if your right handed and coming in from the right) and very gently squeeze the distance in between to about 1”. Don’t go crazy here.... like Brill Cream... “ a little dab’l do ya”
All systems are slightly different and after time, shinkage of the insulating foam on the blend door and the seals that help control the air through the air box may be allowing enough leakage to inadvertently warm the air that is being processed more than necessary.
3) The aspirator that draws the cabin air through the interior ambient temp sensor is not connected properly or is not drawing enough or any air. For example...
If it’s been a cool night and the sun has not warmed up the car but the outside temp (or just your own desire) has you set the system to 65 degree full cool but there is not enough warm air being pulled past the interior ambient air sensor to warm it, the system will misread the interior condition as already cool and throttle down its cooling capacity. Hence, the complaint that it’s not cooling enough.
Confirm that the aspirator “snorkel” hoses of the aspirator are properly and fully connected and that they are also clear. Blow out the hoses with some compressed air to clear away any accumulated debris that may be interfering with the airflow. (Someone trashing around in the tight confines of the area around the aspirator may have slipped off one of the connections which are only attached with friction.)
My A/C works well but never puts out really cold air. What is that all about?
The AutoTemp II is a chill/reheat system. This means that all the air being conditioned is first run through the evaporator and then none, all or a part of it is run through the heater core and directed either to the upper or lower vents. Unless the outside temp is less than about 40 degrees, and the system is set for anything but OFF or VENT, the compressor is running all the time in this system. Likewise, the heater valve will be full open.
If you think that the system is not making cold enough air, you may have one (or more) of the following issues:
(With the upper dash removed for access and, of course, assuming that the system is capable of making air cold through the evaporate down to between 35 and 45 degrees).....
1) One or more of the ambient temp sensors is off spec. Not very likely.... if you got this far. But, if you haven’t checked them up to now, check them all now in accordance with specs outlined in the FSM on page 24-118.
2) Blend door in the airbox is not set correctly at the servo. Adjustment of the link needs to be made so that, at the 65 degree setting on the control panel, the servo actuates the blend door to full open with no or very little blend air. (Typical for these systems after 40+ years)
This is the link that needs to be adjusted. This link is described as “self adjusting” in that, once adjusted, it will self-locate the blend door to the full closed position against the heater core chamber whenever the servo moves to full cold.
To adjust, you need to shorten the distance between the end of the looped hard wire and the curled spring steel link. Thumb on the loop end and index and middle fingers on the spring clip ,(if your right handed and coming in from the right) and very gently squeeze the distance in between to about 1”. Don’t go crazy here.... like Brill Cream... “ a little dab’l do ya”
All systems are slightly different and after time, shinkage of the insulating foam on the blend door and the seals that help control the air through the air box may be allowing enough leakage to inadvertently warm the air that is being processed more than necessary.
3) The aspirator that draws the cabin air through the interior ambient temp sensor is not connected properly or is not drawing enough or any air. For example...
If it’s been a cool night and the sun has not warmed up the car but the outside temp (or just your own desire) has you set the system to 65 degree full cool but there is not enough warm air being pulled past the interior ambient air sensor to warm it, the system will misread the interior condition as already cool and throttle down its cooling capacity. Hence, the complaint that it’s not cooling enough.
Confirm that the aspirator “snorkel” hoses of the aspirator are properly and fully connected and that they are also clear. Blow out the hoses with some compressed air to clear away any accumulated debris that may be interfering with the airflow. (Someone trashing around in the tight confines of the area around the aspirator may have slipped off one of the connections which are only attached with friction.)
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