A/C Vacuum Mode Selector Switch AC Air Conditioning

[amach_one]

Hello everyone, I realize that the air is only blowing through the windshield and the feet. Impossible to direct the air. I wonder if the switch is dead, although I changed it yet one time t but nothing happens anyway. My car has just undergone a complete body restoration but I still have this problem while I am in the process of reassembling the entire interior and dashboard. In terms of hoses, everything seems ok. But, if I turn on the air with the car engine running, the air conditioning compressor starts and there, I have air in my face. In other words, the switch where you can choose to turn on the AC seems not to be working. What do you think ?

Thank you all in advance for your ideas!!

 

[Steve McMahan]

See if these diagrams help:




You’re gonna need them to trace each line to see if you have vacuum at the individuals vacuum motors. Check that the motors hold vacuum and they are getting vacuum when signaled. You can find this stuff in your Ford Service Manual, If you don’t have one and are restoring your car, you need one.

 

[Steve McMahan]

Here’s the other vacuum diagram:

 

[mrgmhale]

I found that in these older cars that used vacuum to move air flow doors open and shut that when there was a large vacuum leak air would predominately blow through the defrost vents. This would also happen in cars climbing a mountain where there was not enough vacuum to keep the air flow doors in the position that sent air through the cabin vents, and it would also blow through the defrost vents. The fix: was to use two vacuum canisters next to each other in parallel. I am betting there is a vacuum hose that is detached somewhere, causing a large vacuum leak in the control head vacuum lines, or perhaps the control head itself is leaking badly enough to cause the problem (I hope not).

I am not sure if that is any help or not. Those are some nice diagrams Steve provided. Same ones I have, so no sense in me replicating his offering.

 

[72mokk1]

My actuators perked right up after I put a drop or two of WD40 where it makes a physical connection. Just a little rust from sitting will lock it up.

 

[Bobby]

Hello everyone, I realize that the air is only blowing through the windshield and the feet. Impossible to direct the air. I wonder if the switch is dead, although I changed it yet one time t but nothing happens anyway. My car has just undergone a complete body restoration but I still have this problem while I am in the process of reassembling the entire interior and dashboard. In terms of hoses, everything seems ok. But, if I turn on the air with the car engine running, the air conditioning compressor starts and there, I have air in my face. In other words, the switch where you can choose to turn on the AC seems not to be working. What do you think ?

Thank you all in advance for your ideas!!

Try to replace your A/C vacuum lines including the cannister. 100 year old vacuum lines are unreliable! I found replacement vacuum lines in 2019 but are now unavailable for 71-73. Below is a link for replacement vacuum lines for 67-68. It might be helpful.

https://www.cjponyparts.com/scott-d...W2CmTzfMq9DQu7r5Yxc6QzfHS8TcSnKAaAu_jEALw_wcB

 

[swice]

I had the same problem and it was vacuum selector, I finally found a metal selector as the plastic one is prone to failure. You can test this by taking the main vacuum hose that comes through the firewall and connect to each actuator to directly test each actuator of the central vents, etc, this drove me crazy until I realized what was going on.

 

[amach_one]

I found that in these older cars that used vacuum to move air flow doors open and shut that when there was a large vacuum leak air would predominately blow through the defrost vents. This would also happen in cars climbing a mountain where there was not enough vacuum to keep the air flow doors in the position that sent air through the cabin vents, and it would also blow through the defrost vents. The fix: was to use two vacuum canisters next to each other in parallel. I am betting there is a vacuum hose that is detached somewhere, causing a large vacuum leak in the control head vacuum lines, or perhaps the control head itself is leaking badly enough to cause the problem (I hope not).

I am not sure if that is any help or not. Those are some nice diagrams Steve provided. Same ones I have, so no sense in me replicating his offering.

That's what i'm thinking also while I already found a torn and repaired hose with a fitting and there might be another one ??? but then it would be under the dashboard...I'll look into that. The diagrams for what i can see seems to be okay on my car and this morning I noticed by looking under the dashboard that if I put on to warm, the vaccum motor of the heating unit worked, i think the control head is working at this time no ?? tell me because me too i hope to not have problem with it !

But the positions to direct the air did not work...I I'm going to have to dismantle everything to see more clearly. Will put some wd 40 also where it's needed..
I'll keep you informed. Thank you for your help, it shouldn't be serious, just very difficult to access...

 

[amach_one]

I had the same problem and it was vacuum selector, I finally found a metal selector as the plastic one is prone to failure. You can test this by taking the main vacuum hose that comes through the firewall and connect to each actuator to directly test each actuator of the central vents, etc, this drove me crazy until I realized what was going on.

Thank you, I'll check that too, it could be that too and....yes! This kind of breakdown drives you crazy !!

 

[amach_one]

Try to replace your A/C vacuum lines including the cannister. 100 year old vacuum lines are unreliable! I found replacement vacuum lines in 2019 but are now unavailable for 71-73. Below is a link for replacement vacuum lines for 67-68. It might be helpful.

https://www.cjponyparts.com/scott-d...W2CmTzfMq9DQu7r5Yxc6QzfHS8TcSnKAaAu_jEALw_wcB

Thank you this could effectively help !

 

[Steve McMahan]

Yea, working on that unit is much easier if 1) you are very thin and flexible or 2) remove the passenger seat. I’m a #2 guy.

 

[amach_one]

It's okay the problem has been solved by removing the A/C switch and changed it by another one. The suction is good now and the A/C only starts when i put the switch on A/C.

Thnak you all for your help !!

 

[mrgmhale]

It's okay the problem has been solved by removing the A/C switch and changed it by another one. The suction is good now and the A/C only starts when i put the switch on A/C.

Thnak you all for your help !!

Thank you for lwtting us know what fixed the issue. I am sure it is going help other fellow enthusiasts, even yezrs from now...

 

[amach_one]

I would add that I was able to change the switch without removing either the dashboard or the face of the gauges. The 2 screws that hold it are accessible from below provided you remove the passenger seat and can lie on your back with a good lamp !!