OK so I recently bought a 94 rx7, one of the AC hard lines where severed so I had the builder I bought it from replace the line, the AC worked perfect for about 30 mins then it stopped. It appears that the clutch in the AC compressor melted away from the pulley itself and then slung some of the melted plastic around the bay (pic attached). The car has a power FC installed and besides an exhaust it is the only real mod, I have heard that sometimes the power FC will make the fan switch not work or only work in one setting because of old wires, the fan seemed to work fine on every setting until the clutch melted. I just want to confirm that any of the mods didn't cause the clutch to burn up and it was just old age before installing the new one. Anybody have any insight on this issue or experience something similar? Thanks for the help in advanced.

 

The only times I have seen a fan clutch melt were because of insufficient current going to the clutch, caused by a voltage drop in the system. Poor wiring, mainly. The clutch doesn't engage solidly, slips, and the heat of slippage melts it.

It's POSSIBLE that if the fan (cooling fan, not HVAC fan) was not working correctly, the high side A/C pressure got high enough that it took enough power to turn the compressor that it made the clutch slip, but that is very, very thin. There's only a small handful of A/C compressor designs, and all of them will happily build enough pressure to blow out the safety release (about 500psi) without the clutch slipping. And you'd notice long beforehand that the A/C wasn't very cool.

 

Thank you for the quick response, I was worried it might be more serious than a new compressor. So I guess Ill look into how the previous owner wired the car before I spend even more money and end up burning out another clutch. Any ideas on what to look for besides the obvious?

 

Nope. Crispy wiring, corroded connections, and check the relays.

Were it in my shop, I'd install the new compressor and check the voltage difference between the wire at the clutch and battery positive. It should not be lower than .5v with the clutch engaged. The ones that had slippage issues were dropping five-six volts in the wiring. I'd check the ground side /s voltage drop to ground too, although the ground side is usually much simpler.

 

Ok, Ill see what I can come up with. Thank you for the help and all the info. Hopefully it'll be something easy.

 

OK so UPDATE PLEASE HELP.

I think I found my wiring issue! In the first pic you can see how the previous owner/shop had a wire in place of the relay, I assume it was so they could trick the clutch into engaging so it will pull in the refrigerant with an empty compressor, well either way they left it in and (with my limited knowledge) I figure it burned out the AC clutch. So good news is they sent me a new AC compressor and I bought a relay from Mazda ($30 WOW), now my question is, can I just remove the new clutch (second pic is of the old melted one) and put it in place of the old one? (third pic is of compressor w/o clutch) That way I wont have to evac and recharge the system or worry about a new dryer/accumulator since it will remain closed. Or is more of the compressor damaged and I should replace the whole unit?

Thanks for the help

 

Clutch replaced thanks for all the help. Please delete