C2 air cond electrical problem

[Randy S.]

The air condioning on my 66 has just quit. I do not have any power to the ac clutch or any of the blower speeds.

main 20a fuse in heater ac fuse block is good ( owners manual says 30A ;existing fuse is 20A?)
15a blower fuse ( for high speed only) is good ( owners manual also says 30A? doesn't seem right for 12ga wire)

I was suspicious of the switch on the "AC pull" cable. I am getting contact closure but no voltage at the clutch coil.

I also am getting 12 volts at the high speed blower fuse.

I have service manual asnd assembly manual if someone wants to reference chapter and verse. Any help would be appreciated.

Randy

[Ed Jennings]

Re: C2 air cond electrical problem

I think the first thing to clear is the switch behind the glove box. I know sometimes I have to pull my "air cond pull" knob out a couple of times to get the switch to make up.

[Peter L.]

Re: C2 air cond electrical problem

Randy - I agree with Ed on checking the switch on top of the heater/AC box. I've had one of those go south. Your fuses are interesting but if the're good there shouldn't be a problem. But, C60 cars did get a 30A fuse in the HEATER BLOWER slot in the fuse block (moving cold air takes more work than moving hot air so the blower motor is most likely heavier duty) and the fuse holder in the C60 electrical harness (red wire) is usually marked 30 AMP. Pete

[Randy S.]

Re: C2 air cond electrical problem

Ed and Pete
I believe the switch on the air box, air cond switch, is working. One lead from the contacts comes out at the comp cluth and the other side of the switch contact comes out to the blower resistor. I removed the connectors and with an ohmmeter I get contact closure, 0 ohms, by pulling the "air pull" cable.

But I have no voltage at the clutch. With a good fuse in the fuse block I get voltage at the left side of the fuse block but not at the right????

[Peter L.]

Re: C2 air cond electrical problem

Randy - The fuse block situation defies the laws of physics. If the fuse is good, you should have electrons at both ends. Double check the fuse and the fuse holders for corrosion. Pete

[Wayne W.]

Re: C2 air cond electrical problem

And, Sometimes the fuse will look good, but be unsoldered down inside the caps.

[Randy S.]

Fixed it kinda!!

Pete,

I agree; should be voltage at both ends of the fuse. Anyway probing around with my tester on the line side ( left side I assume)of the fuse holder I could hear some clicking. Finally the fan started blowing and compressor clutch works.

I have an intermittent connection at the fuseholder. I suspect a loose fuseholder on this circuit or possibly the firewall harness connector. No other electrical gremlins. Hopefully it works thru the summer.
Thanks for your help.

Randy

[William C.]

Re: Fixed it kinda!!

don't discount simple corrosion on the contact faces of the fuse terminals, or a relaxation of the terminal providing the power feed to the buss behind the fuseblock (from the IP harness)

[Dick W.]

Re: Fixed it kinda!!

Randy, I would be leary of an intermitent connection. They can heat and short out. Be careful.

[Randy S.]

Re: Fixed it kinda!!

Tell me more about part 2 and how to check for it.

The blower relay pulls in when I put the 12V test light on one side of the heater AC fuse. It seems to me since I have power there it is not the connectors at the firewall from the wiring harness. Why would test light at AC power fuse pull in the blower relay?

I've tried cleaning the fuse block clips. Any suggestions?

[William C.]

Re: Fixed it kinda!!

depending on how you have the test light configured, you could be supplying power or ground thru the test light.

[Craig S.]

Re: Fixed it kinda!!

I agree with Dick - a poor (lossy) connection can cause resistive heating and burning at the bad connection point, it could ruin the fuseholder, fuse block, or firewall connector. It could even cause a fire (not likely, but possible). I would trace it now and NOT count on it continuing to be operational, you are close to the isolation point, just follow through and repair....Craig

[Randy S.]

Re: Fixed it finally

Finally figured out I was not getting a connection between fuse clips and good fuse. When I shorted the test light across the clip and fuse barrel the I could hear the fan start.
I now have AC again
Thanks for all the suggestions from all you "sparkies"

Randy