[raidex1]

I have a 68 GTO with factory a/c. Last year everything was gone thru and new fan was also installed and recharged with R-12 and blew at 42 degrees and all worked well.
Yesterday the a/c blew ok at idle and maybe up to 10 or 15 mph but at higher speeds I could barely feel the cold air coming out of the vents. As I recall it didn't do better when I let off the gas when I was going faster.
I'm thinking maybe vacuum but not sure.
I would appreciate any feedback. Thank you. Rick

[OG68]

evaporator core is probably froze up preventing air flow through it. Time to check your pressures and refrigerant for leaks

[Bruce Clarkson]

Pretty easy to check electrical power on blower motor. First, just check to see that it seems to change speeds based on the control's settings. You can do this with the key in ACC, if you want. If that shows a problem, then, from my Bonneville experience, there are several possible problem areas. The switch contacts in the control in the car can fail. You can tell be looking at the changes in power supplied to the blower's resistors (generally in the plenum). The resistors can open but that probably would not keep high speed from working. They can be checked with an ohm meter or visually inspected. There is probably a blower high speed relay that is used to keep the in-car control from having to handle all the current from the blower motor with run on high. I've seen these relays fail (on my AMCs) and have seen the connectors on the back of the relay get pretty well cooked (on my Bonneville). nd, of course, if you are sending power to the blower motor at high setting and the blower is not turning, blower motors can be bad.

If the blower motor does what it's supposed to, good luck looking into the other controls. Mine's a Bonneville and it was a pain. I think the GTOs have a different setup so the specifics of my experience there are probably not too applicable.

Bruce Clarkson

[73ta]

Even with a functioning system, fan doesn't blow very hard. I helped mine by sealing up all the vents under the dash with foam & duct tape. With all the pipes and vents sealed it blows much better. Factory ducts have a lot of leakage.