Air Conditioning question

[Philossifer]

Originally Posted by Ieatcamaros

Where does this "diverter" get it's vacuum source, particularly on an 89 gt?

Thanks for the link, Maroon5.0.

To be honest, I'm not real knowledgeable about the vacuum routing on these cars. I do know for sure that the temperature blend door is controlled by a cable, but the switch that selects where the air goes (vent, floor, defrost, etc.) is vacuum controlled.

I guess the first place to start is by determining if you have enough vacuum. (Do you have a brake bleeder like a "MightyVac”?) They're pretty cheap and well worth the investment, plus they’re great for testing for vacuum leaks.

On the firewall is a “Vacuum-Tree" that gets its source of vacuum from the intake manifold. From there, the Tree sends the vacuum to deferent places where it's needed on the car. One place is the A/C Heater control in the dashboard. Hook-up the MightyVac to the Vacuum-Tree in place of the hose that goes to the intake manifold. Pump up the vacuum and watch the needle on the gauge. It should hold the vacuum for several minutes. If the vacuum drops rapidly, you'll have to start checking all the vacuum hoses including the one leading to the heater control and the control itself. If it does hold vacuum, try operating the heater control with the engine off using the MightyVac as the source of vacuum. If the control works, then you know you don’t have enough total vacuum at the tree when the engine is running.

Maybe someone else can give you more information about checking out vacuum problem....Like I said; it's not really my expertise!
Good luck,
Phil

[Ieatcamaros]

After reading your reply saying that the diverter was vacuum operated, I started checking things out. Yesterday I noticed this little thing on the firewall (in the pic) had a line going into the dash down where the evaporator core is. I had put a plug on it (where the vacuum line is now). I took the plug off and put a vacuum hose on it. I can now select where I want the air to blow. My hat's off to you Philosofer. There is no telling where that thing originally got it's vacuum source, but it now comes directly off the vacuum tree/manifold. I put a pic up so if anyone else has this problem they can see what has to have vacuum before the diverter door will change directions.

[Philossifer]

Originally Posted by Ieatcamaros

After reading your reply saying that the diverter was vacuum operated, I started checking things out. Yesterday I noticed this little thing on the firewall (in the pic) had a line going into the dash down where the evaporator core is. I had put a plug on it (where the vacuum line is now). I took the plug off and put a vacuum hose on it. I can now select where I want the air to blow. My hat's off to you Philosofer. There is no telling where that thing originally got it's vacuum source, but it now comes directly off the vacuum tree/manifold. I put a pic up so if anyone else has this problem they can see what has to have vacuum before the diverter door will change directions.

Glad it worked out for ya ! I see in your picture the inlet and outlet of the evaporator..... Did you remove all the A/C stuff? If you ever plan on getting the A/C up and running again, let me know. I can give you lots of tips on how to get it to cool with R-134a just as good as it did with R-12. (and I'm not talking about using a conversion kit you buy for 35 bucks) Those things are junk and will eventually kill any A/C system! ! ! ! !

Mine's an '89 LX; The R-12 refrigerant leaked out when I put a new engine in it. I've got R-134a in it now and it'll freeze you out even when idling for a long time. The whole trick to getting R-134a to cool good in an R-12 system is to get all the old oil out, flush the condenser and get as much air flow over the condenser as possible. Plus, the old R-12 A/C components on these Mustangs are very good pieces and can easily stand up to the higher pressures of R-134a.

Again, glad to hear you got your heater control working!
Phil