FE Mustang or Cougar information needs on A/C function. ( Factory Air)

[Keith Stevens]

I am in need of some information on function if anyone has the Selectaire  Cougar or Mustang. I have a 67. However, the 68 should be the same.  The question concerns vent and blower function. I have not charged the system yet.
If anyone has a vehicle that functions correctly and has a few minutes it'd be appreciated.

[stangbuilder]

how can i help. was in the auto a/c business over 40 years

[Keith Stevens]

The questions are very specific. Related to operation with switches in particular operation positions.

[Gaugster]

Do you have the service manual? It contains a matrix of the various switch inputs vs baffle positions etc... If not I can take a photo and share it. Manual has been indispensable to me for rebuilding my heater box and AC.

[stangbuilder]

So ask away i will do the best i can to help you

[Gaugster]

Here's the matrix and diagram from the 1968 manual. Applicable for the Mustang and Cougar. This along with decades of experience should be everything you need.

[Keith Stevens]

I assume you have a 67-8 car with factory A/C?   I noted that no matter what position the selector lever is in on the panel the vehicle is off I hear the clutch engage when the blower is turned on even with the AC off.   The AC servo switch should be open until the door is changed from heat to AC. When the vacuum motor closes the door it completes the circuit on the duct and then the thermostatic switch is the other. 
However, I don't have the "coffee can" style vacuum reservoir. I have the large football style on the right side.  I did note the NOS vacuum check valve wasn't keeping the flow in one direction so perhaps it wasn't holding enough vacuum to change the heater door to close the switch on the blower housing.

I would be disappointed if I can't just use the blower with outside air with the AC off.

[Gaugster]

I assume you have a 67-8 car with factory A/C?   I noted that no matter what position the selector lever is in on the panel the vehicle is off I hear the clutch engage when the blower is turned on even with the AC off.   The AC servo switch should be open until the door is changed from heat to AC. When the vacuum motor closes the door it completes the circuit on the duct and then the thermostatic switch is the other. 
However, I don't have the "coffee can" style vacuum reservoir. I have the large football style on the right side.  I did note the NOS vacuum check valve wasn't keeping the flow in one direction so perhaps it wasn't holding enough vacuum to change the heater door to close the switch on the blower housing.

I would be disappointed if I can't just use the blower with outside air with the AC off.

I have a 68 with factory A/C. However it was broken when I purchased. So I can't simulate your condition. My service manual is for 68 also. Take a look at the "Clutch Switch" row of the table I shared. That row compared to the columns shows what the system is suppose to do. Hope someone with a working system can chime it. I didn't think the compressor could kick in at all when the system wasn't charged. I noted that each of the individual vacuum actuators needed about 17 in-hg of vacuum for full travel.

[Keith Stevens]

I installed the factory components. It's a VERY simple system and wiring is all but impossible to make a mistake on.  However, there are the two switches that had to do with completing the clutch circuit.  The thermostatic switch on the evaporator housing and of course the one on the blow housing ducting that closes when the vacuum motor closes the door on the floor duct.  It just didn't make sense to me that the blower motor can't move air through the dash ducting without the AC being set to run.  Systems are the same 67-8 with exception of how the circuit breaker is set up for the clutch.

[Gaugster]

Looks like only Heat and Defrost settings disable the compressor. Nothing an additional toggle switch and relay couldn't fix. But original is cool.

[Keith Stevens]

This is somewhat helpful. It just made no sense for form and function.

https://www.hotrod.com/articles/troubleshooting-classic-mustang-climate-control/