Just converted a c to 134. I used classic auto air system, went in nicely. I now have a problem with burned wires. The fan was working on all speeds until I went to charge the system. At first only the high speed worked. On my way home I smelled something burning and then my blower quit. When I got home I saw The red wire, that I believe goes to a relay burned and the wire was broken from the heat. I replaced the wire, and it did ok for a few minutes. When I raised the rpm to about 2000 that wire burned and the power to the blower motor also burned. I replaced that wire and installed an inline fuse on the power to blower. It did fine until I raised the rpm. The 20 amp fuse blew and when I replaced it with a 30 amp, it blew when I just turned the a c on. I'm a bit green on electrical issues and was wondering if anyone had any ideas. Don't know if it could be relay or blower motor, or anything else as I had the whole heating and cooling system apart.   thanks                                                                                                                                                    p.s.  the worst thing I've ever done was when I changed the heater core. It didn't leak, but I changed it anyway since I was doing the a c. I was worried that as soon as I got the a c done it would then start leaking. My vocabulary got a lot more colorful.     

 We're gunna need a little more info on this one.
What all did you change, exactly? Did any o f it require modifying the wiring harness?
Do you have, or can you get some pics of the wiring that is melting? Is it buring under the dash, or out under the hood?

Something is obviously not right....I wouldn't keep tempting fate by just replacing the burnt wiring without finding and correcting the problem.

thanks for the reply. I replaced everything from evap. core to condenser. The wires that burned are under the hood The first to burn was at a plug in the harness for the ac i think. It was red and went int the relay. The other was in the same plug. It has 2 black wires coming off of it, 1 going to the same relay that was not damaged, the other was a black wire going to the terminal on the engine side of the blower motor. That wire had the insulation melted off.  I also read that the resistor that goes in the heater box controls the low speed for the blower. When I replaced the a c I had everything apart and it's possible that part may have been damaged. I tried to be careful, but sorry to say, I may get clumsy at times.I've never done ac before, but i"m trying to learn. Maybe in time I can be of some help to others. thanks

I installed it on the black wire under the hood that goes to the engine side of the blower motor. There was another wire in the plug that goes to the relay.

I think the wires at your blower motor might be reversed. the 2 black wires that come from the same connector 1 goes to the blower relay the other would go to the ground clip of one of the mount bolts of the blower itself. the single wire from relay goes to the hot of the blower fan.

thanks for the help. I'll check what you suggest.

Ed zachary what I was thinkin....direct short at the blower motor.
The resistor does control fan speed for low, low medium, and medium speeds. The high speed works directly from the relay.

maider        just car back from restore shop,  heater fan not working  also no start,now where is the blower motor     just read motor gets power for stater    maybe  same wiring is not right  . heater blower fan only works on high  I have no power   I will keep looking and see how you make out dwa

guys   where is the heater/ac  fan motor