A/C relay wiring connector burned
 

First time asking for help on here, hoping to find someone who has had similar problem, keep me from butchering my original wiring harness or chasing the wrong monkey!

I have a 1974 Cheyenne Super with original a/c (R12) system with no modifications or prior hacking. Recently I noticed that my intermittent speed for blower motor would only work on full speed, nothing on the lower speeds. I checked the fuse and wiring connections, while doing so I noticed the blow motor relay was super hot!!!, I pulled the terminal connectors and discovered that my 3- way was melted, and the (blue) wire appeared to be burnt. I have had no other issues with the a/c system other then loss of freon in past due to a leaking hose. I'm guessing that maybe the blue wire is making contact with either the orange or purple wire inside the harness? or the blower motor relay shorted out? Any suggestions would be helpful!

Re: A/C relay wiring connector burned
 

Most likely the connector wasn’t making good contact. When you try and put a lot of amps through a loose connection, it makes resistance, which makes heat, which makes more resistance, which makes more heat, and on and on until something melts or catches fire. I’d replace the entire connector and when you install, make sure it is a tight fit.

Re: A/C relay wiring connector burned
 

Thanks for the advice, figured it was something simple without going through the whole system! I'll replace the terminal housing and at least the connector on the blue lead and hopefully it solves the problem! I'll also check the HVAC relay to see if the male end is loose and replace if needed! Thanks again!!!

Re: A/C relay wiring connector burned
 

you may have a motor going out. When they go out the resistance starts to build in the motor requiring more juice which create heat

Re: A/C relay wiring connector burned
 

Okay, I'll monitor the blower motor, seems to be okay, not running hot. Thanks for help!!!

Re: A/C relay wiring connector burned
 

If your AC is working correctly and the temp slider is all the way left on cold, you only have high blower speed. Move the temp slider slightly right about 1/4". You will feel a slight bump then you will have AC with all fan speeds. These blow on low all the time while key is on even while setting is off. I have found a way to delete low fan if you would like to know. I didn't like the low blower on in the winter cause when engine is off then restart it blows out the top vents till the vacuum builds up to deflect air to heater (floor).

Re: A/C relay wiring connector burned
 

Thanks for the advice, I knew from experience that the blow motor blows high all the way left, regardless where the selector switch is, and here in southern California its rarely cold to need heat at full start up, its appears that the terminal was lose on the relay, causing it to arch and cause more amps, which induced the heat. I'll let you know what the final verdict is after I replace the terminal housing.

Re: A/C relay wiring connector burned
 

Replaced connector and 3-way terminal and system is working fine! Thanks for all your input!!!