AC wiring getting super hot at panel

[dyount]

Long story but... I haven't had functioning AC since I got the car 20+yrs ago and just did a Griffith retrofit. I replaced the hoses etc myself and got it back from the shop yesterday now that it's charged etc and functioning. Now, after a bit of running, the load side of fuse 20 (25A) is literally burning hot and melting the fuse without tripping.
During the work that I did to replace the system I did replace the front condenser motor with a same part/similar motor, removed and cleaned the evaporator motor. Both motors are functioning (fine??) as far as I know. What I do not know at all is why the system was not functioning when I bought it years ago and why the conductor/s south of power would be getting so hot as to melt the fuse without tripping.
Could this be either a hot/ground reverse on one of the motors or an issue with a wire being damaged possibly years ago?

[GH85Carrera]

One thing to do is ditch the crappy plastic core fuses, and search for a kit of ceramic core fuses. Then clean with steel wool or similar product the contacts of the fuse holder, and replace all the plastic fuses.

Then get an amp meter and test the individual components for current draw. The power seats use the same fuse, Make sure it is not drawing power unless you are running the seat motors.

I presume you replaced the factory AC relay with the Griffith's one in the kit. Double check his instructions for the wiring setup.

I use his hurricane blower, and have four condensers. The two condensers in the rear fender both have fans, but they are powered by the power in the engine compartment.

I have had many 11 to 12 hour drives with the AC running hard in 100+ degree heat, and no issues with too much heat in the fuses. They do get hot, but not extreme.

[dyount]

83 911 with no seat motors
If I had too much power draw it should be tripping the fuse ??

[911obgyn]

Clean connections, including grounds.
Plastic fuse bodies melt by looking at them.
Make sure the fuse holder grips tight and as above get ceramic fuses.

[targa80]

I would go with the amp meter in series with the fuse and then use a schematic to determine where to disconnect each component one at a time in the circuit to see where the high current draw is coming from. Once found check contacts for corrosion, poor ground continuity or if a fan motor check for worn brushes, gummed up bearings or just plain frozen motor.

[47silver]

I would firs check the compressor clutch. Should be >2 ohms and < 5
The clutch is a large relay that draws a high current.
Run the ac disconnect t he clutch, check amps or wait to see if the fuse cools down.
Check the grounds from engine to chasis
I would fuse the clutch separately from the fans and the fans individually.

[targa80]

From the 81 schematics factory air uses fuse 20 (25A) to supply power thru the ac fan switch for the ac compressor clutch, the front belly condenser fan and the evaporator three speed fan. The circuit also includes the ac relay, cooling fan relay, evaporator fan resistor unit and the temp switch.

[fred cook]

You need to split off some of the a/c power load from fuse 20. Fuse 19 is for the headlight washer so if your car does not have that option you can use 19 to relieve the load on fuse 20. That is what I did on my 1980 SC. Good luck.

[dhanl82]

I did what Fred has suggested, solved the fuse overheating issue.

[targa80]

Originally Posted by dhanl82

I did what Fred has suggested, solved the fuse overheating issue.

I would then recommend you drop an ammeter in line with each fuse to test the average current draw on the modified circuits. Don’t maintain a 25 amp fuse for a modified circuit now drawing ~7 amps. Instead used a 10, 12, or 15 amp fuse. Also, if you have a schematic for your car modify the drawing to show your changes because in the future you may need to be reminded of the change you made.