non-vette AC problems

[AnytownUSA]

My nephew has a 91 Nissan 240SX on which the AC has quit working. I cannot tell if the compressor is shot because every time I turn the AC on it blows the 10amp fuse in the fuse box. I do not hear the compressor clutch engaging as the fuse blows immediately. The blower works great, but right now it is only blowing hot air. It is an R12 system that I plan to convert to 134 but I want the system working before I do that. Any ideas as to why I would be blowing fuses that are not running the fan/blower? Does the compressor have an electric feed to it? I thought the compressors only pulled from the engine and not from the electrical system. Evidently I was wrong. It does not have any automatic air or anything like that, and it does not matter vent setting I have it on it blows the fuse regardless. I do not know how much current the AC is pulling through the 10amp fuse yet but I will check that tonight if that would help anything. Thanks for your help.

 

[JohnZ]

You really should have the Shop Manual for the car so you understand the circuitry involved with the A/C system; the compressor has a 12-volt feed for the clutch coil - that's what engages the clutch. If the compressor clutch coil (or the feed wire to it) is shorted to ground, that's what's blowing the fuse immediately.

 

[LarryBible]

I highly recommend www.aircondition.com Once there click on "Straight to the Board."

Post any auto a/c question there and it will be answered quickly and accurately.

Good luck,