Q #2 73 A/C Problem

[magoo]

Hi Jeff
Your fan speed won't have anything to do with your compressor engaging. It sounds like your system could be so low on freon that there is not enough pressure to engage the clutch. Do you have the low pressure switch Bill showed in his pic? I don't think you do. Has this system worked recently? If so and it blew a large leak, you should see oil at the place where the leak opened up. If it's empty, it may make sense to convert it to 134 at this time. I wish we lived closer I still have some r-12. The fuses I have here have those same letters on them and I don't remember what they stand for. I will research some old Chilton manuals and see what I can find. Do you have guages to charge this system yourself? I will try to talk you through it if you want.

Mike

 

[CAPNZ]

Thanks Mike,
I don't believe I have that switch on mine.
No I don't have guages.
The A/C never worked. I just got the car.
I just wanted to get the Hi-Fan working again before I take it in because I know they'll rape me on that.
TIA
"Jeff"

 

[CAPNZ]

Ok, there's a fuse on one end of the in-line fuse. On the firewall. It looks like a relay but it's printed 12VDC 30AMP. There's an orange and a red wire going to the posts on it. Also stamped under the posts is "AUX" and "BAT". Now, these wires go to this relay,(I think that's what it is), next to the washer bottle. Should I check this for Hi-Fan?

Thanks Mike!
I just went out and checked the voltage of the in-line fuse with my DVM. It jumped back and forth from mV to Volts. I could'nt make out the volts because it went to fast.
Almost like a capacitor was charging & discharging. I'll check back tonight.

"Jeff"

 

[CAPNZ]

I wanted to include an attached picture. I don't know why it didn't work. I've done it before on many sites. ?????

"Jeff"

 

[JohnZ]

Ok, there's a fuse on one end of the in-line fuse. On the firewall. It looks like a relay but it's printed 12VDC 30AMP. There's an orange and a red wire going to the posts on it. Also stamped under the posts is "AUX" and "BAT". Now, these wires go to this relay,(I think that's what it is), next to the washer bottle. Should I check this for Hi-Fan?

That's a self-resetting 30-amp thermal circuit breaker; the power feed goes to the "Bat" terminal, and wire to the load (device) connected to it goes on the "Aux" terminal.

 

[CAPNZ]

I just pulled the console out for the second time. I dropped the clip for the shifter linkage and it went under the bracket. So, I had to pull that. All was not lost. Got the clip, found a trim screw and two silver dimes. I got the heater control & switch out again and I'll keep you posted after I check it. Boy, it's sure nice GM gave us all this room to do this stuff. LOL
"Jeff"

 

[CAPNZ]

BINGO HI-FAN now!
I missed one of the terminals on the switch. This is VERY,VERY,VERY easy to do because you can't see them, i.e. terminals 2 & 3 if you missed one because the plugs hide them. When I looked at them both plugs looked like they were in but they weren't.
Here's a tip, put the back plug in first, (looks like an L) then the front one,(terminals 1,4,and 2).
Also here's the continuity for the blower switch in a 73. I drew a diagram and documented it to make sure the switch was ok.

Switch Off = 2 & 6 continuity ( this is because even though the switch is off when the A/C control is on the blower works at very low speed. I think it's to keep Co from entering the cockpit).
Switch 1 = 1 & 2 continuity
Switch 2 = 1 & 3 continuity
Switch 3 = 1 & 4 continuity
Switch 4/HI = 1 & 5 continuity

"Jeff"

 

[CAPNZ]

MIKE;
I checked the voltage at the Green & Black wire going to the A/C unit with the control Off. I got 0.00 Vdc. I turned the A/C control on and I got 12+ Vdc. So this is good. Now I'll take it in and have it checked for low Freon.
TIA
"Jeff"

 

[magoo]

Good job Jeff. Thanks for recording the info on the blower switch. Wish we were closer so I could help ya with that recharge. Keep in touch.

Mike