1976 C-10 Air Conditioning

[truxson]

I need some help with the vacuum line routing for my A/C system....Mainly from the vacuum accumulator on the firewall.  Can anybody shed some light on this subject?

[blazer74]

From the ball on the firewall  the  larger fitting/line goes to the intake manifold in the back for the vac  supply source.
The smaller line/fitting from the ball goes over the a/c box and thru the firewall to the a/c controls.

[truxson]

I'll check that out tomorrow.  I certainly appreciate the information.

Regards, david.

[Irish_Alley]

hows this

[truxson]

I believe that will be helpful.  I appreciate the illustration. 

Regards, david.

[truxson]

First, let me say thanks to the folks who sent me some advice and diagrams regarding the vacuum setup for my 1976 truck A/C.  I found the connections and got that working.

As I said earlier, the A/C hasn't worked in years....So now I have it blowing cold, but still have a problem, or two.  Let me get them solved one at at time....When I set it on 'Max', the blower fan works as it should...for 4 or 5 minutes.  Then it cuts off.  Returning the lever to 'Normal', I can get the fan to work in other positions.   My first thought is that the relay on the outside box is bad, but I can't seem to confirm that.  It works, then it doesn't, then it does....

Can anybody give me some advice?

Thanks, david.

[MrFiveOh]

First, let me say thanks to the folks who sent me some advice and diagrams regarding the vacuum setup for my 1976 truck A/C.  I found the connections and got that working.

As I said earlier, the A/C hasn't worked in years....So now I have it blowing cold, but still have a problem, or two.  Let me get them solved one at at time....When I set it on 'Max', the blower fan works as it should...for 4 or 5 minutes.  Then it cuts off.  Returning the lever to 'Normal', I can get the fan to work in other positions.   My first thought is that the relay on the outside box is bad, but I can't seem to confirm that.  It works, then it doesn't, then it does....

Can anybody give me some advice?

Thanks, david.

If you haven't had AC for a while i would check your blower motor relay, resistor, and Switch that turns it on and off. I just installed a 134 system in my 74 and replaced all that stuff with new since it hasn't had AC for a while.

[bd]

....When I set it on 'Max', the blower fan works as it should...for 4 or 5 minutes.  Then it cuts off.  Returning the lever to 'Normal', I can get the fan to work in other positions.   My first thought is that the relay on the outside box is bad, but I can't seem to confirm that.  It works, then it doesn't, then it does....

Can anybody give me some advice?

There should be one 18-gauge orange wire and one 10-gauge orange wire connecting to the blower relay.  The 10-gauge orange connects to B+ at the firewall junction block through a 30-amp fuse.  The 18-gauge orange connects to the blower switch.  When the blower stops working, use a test light to probe both orange wires, one-at-a-time.  If either wire is dead or illuminates the test light dimly, that is the circuit introducing problems.  Post the results.

[blazer74]

If the blower does not work at all on max hi now you have blown the fuse mentioned above. If it works intermittent then it's not the fuse.

If you can control the fan on normal the resister is good.

The relay usually works or it doesn't but is a cheap replacement part as well as the resistor.

If the fan itself is in bad shape and drawing to much current the wiring could show signs of overheating.

[hatzie]

The blower gets power through a switch in the mode lever.  HI uses the power to trip the relay.
If it's intermittent on HI then I'd check that switch is clean first.  You can clean it with Deoxit D5.

Sent from my SM-P605V using Tapatalk

[truxson]

Thanks for all the suggestions.  I am 'off' this weekend for the first time in several and I will check the things everyone suggested and post what I find.

Regards, david.