Hello Everyone,

I'm trying to figure out our GTO's air conditioning system.  First, the high fan speed doesn't but I believe the high speed relay on the fire wall may be the culprit from what I've read online.

The other thing is the ac unit appears to be making cold air, at least the POA valve is nice and cold, but the cold air isn't getting into the car.  I'm not sure if I have a leaking air hose or if a diaphragm isn't working.

Anyone out where have some ideas on what's going on?

Thanks in advance!

 

Edited April 24, 20251 yr by reveredGTO

John

Yes the high speed relay on the firewall is probably the culprit for the high speed fan.

I suspect you are not getting any cold or hot air at all because the flap door between the hot and cold side of the heater core is not opening and closing properly. When you move the controls on the dash, they are connected to cables or rods (that run behind the glove box) that move the trap door in the heater core box between the hot and cold sides of the core. I am willing to bet they are either disconnected or connected incorrectly.

I would recommend taking the glove box out. With a flashlight, move the controls on your dash and see if or where the rods are moving anything attached to the heater core box.

Another problem could also be the vaccum octupus (as I call it) under the dash may have disconnected vacuums lines. That thing is a true PITA.

Edited April 24, 20251 yr by Frosty

I printed the page out of the service manual and looking at the drawing, I'm wondering (hoping??)  if the temperature door is stuck in the Max Heat position and a little persuasion will pop it loose.  It seems I can't turn the temp down at all.  I have a set of vacuum lines just in case.

should be a 20 30? AMP fuse coming off the alternator wiring harness that may be blown.  also a connection by the evap case under the hood may be loose. but yes the relay in on the firewall.

my Lemans i had to change a couple of the vacuum pots to get everything working properly. the diaphragms  leaked vacuum. the ones on the case in the car.

It's a 30 Amp fuse.  That was blown also.  Hopefully I have some time this weekend to work on it.  Life keeps getting in the way

Well, the relay was the root cause for no high-high fan.  It's fixed!  I haven't checked the other issue of cold air not getting in the cabin, but I'll be getting into that soon.  While I'm at it, I need to install a thermal vacuum actuator in the air cleaner.  It's been missing from the air cleaner since I bought the car.  Of the two ports, does anyone have a diagram that shows which port on the actuator plugs into the engine?  Does it matter?

TIA