Need some help on the stock A/C wiring

[Project1970]

Okay...I go through a blower motor switch every year, if not more often, and I'm sick of it...

So, what I want to do is bypass the stupid thing altogether and run the fan off of a relay, no speed control, but I don't care. The only snag I can think of is how is the A/C compressor turned on when the switch is in any position other than OFF? (I say that because my HI position is disconnected at the fuseblock (wiring gets too hot) yet the A/C compressor is still engaged...)

This is more or less an extended stopgap fix until I can afford a Vintage Air unit.

[tom hand]

I think the factory wiring is too small and when it gets old it just does'nt cut it. Mine burnt up the connector at the fuse box several times and completely melted the connector on the fan switch. I wound up with two big toggle switches, one for the fan and one for the compressor...that was my stopgap fix till I got a Vintage Air

[Class of 69]

Have you tried replacing the blower motor?? High resistance in the blower will cause over heated wiring. Also, check for loose, or corroded connections at all points..i.e. resistor,blower, switch. etc.

[Project1970]

Replaced the switch 4x, the connector twice (soldered last time too...), and the motor once...no difference.

[tom hand]

I soldered the connector on at the fusebox...replaced the blower motor,high speed relay,resistor block, and cleaned every connection I could find. It would work great for six months and the meltdowns would return. I really think the problem with the whole deal is the way it is powered. It has the little 1/4 inch quick connect at the fuse box, and I believe the system pulls more amps than that connector can handle. It builds up resistance, the voltage drops, and the meltdowns start. Probably the best fix for the stock setup is to lose the 1/4 inch connector and get the wiring some real power. Maybe run a wire out to the block beside the battery. Don't forget to fuse it.

[Project1970]

Here's what I was thinking of doing:

Get one of those bigass Bosch relays; one of those 30amp units. One of those should handle the fan no problem, right? I'll run it it's own +12V fused feed from the battery. From there, to the fan, and the fan to ground. This will be controlled by one side of a DPST switch in the cab. The other side of the switch will be connected to the two wires that switch the compressor on - either directly or through another relay, I haven't decided that yet. Would the compressor clutch require a relay as well?

Sheesh, from the sound of things, I might as well add the relays to my headlights too

[Project1970]

A quick bump to see if there's anyone else who might know.

The A/C clutch is similar to the TCC in a 700R4 in that 12V to it means it's engaged, correct?

[Kid]

To answer your question of how the A/C is turned on. There is a switch located behind the air box plenum (air divider b/t heater out let and A/C ducts). When you move your middle lever (A/C--heater) to the left, the plunger on switch located behind the plenum box is depressed, completing the circuit to compressor.

[Project1970]

Okay, I've just got one thing left to figure out - the rest I've got almost ready to go. I figured I'd bump this thread before making a new one. I remember, when putting in the blower motor, only connecting a small ground wire...where is the feed wire, so I can solder a new wire to it and power it via the relay?

[anthony_1269]

I have the same exact problem w/my A/C. Got fet up w/it. So I spliced into the wire that ran to the A/C fan. Ran a wire from the fan to a toggle(35 amp) switch, toggle switch to a 30 amp fuse(just to make sure it wouldn't burn up my fuse box), then from my fuse to the fuse box where it had and extra accessory connection. Once I flip the toggle switch on, I still have to turn on the orignal A/C switch to activate the compressor. But works fine, better than original. Only set back is that it only works at a constant speed. There is no option on how fast you want the air to blow. But really works better than orignal. Been going since beginning of June w/no problem...

JAA