47-55.1 no spark after vintage air install

[evilokc]

title says it all. wrapped up install. tested fine in the garage. turned on a/c while driving and truck immediately died. have zero spark. I read that the aftermarket systems draw a ton of amps. my working theory is that the draw from the a/c and electric fan on the condenser was to much for the old h.e.i coil. I hope that's it. I don't like my truck being down. anyone had this issue or have suggestions?

[mr48chev]

Is the unit hooked to the accessory side of the ignition switch or the ignition side?

Do you have relays so the amp load to the AC components isn't running directly though the ignition switch?

Original wiring or aftermarket wiring kit?

[MiraclePieCo]

Did it just blow a fuse?

[nvrdone]

will it start & run when you turn off the a/c?

[mr48chev]

Thinking on it, did you by chance knock a wire loose under the dash?

Do you have the correct Hei plug with the clip on the wire to the distributor? If you just have a female slide on the wire they can loose contact real easy and still be in place. Had that happen way too many times on my 71 when I changed to HEI and went cheap with the wire end.

First thing I would do though is get my test light or meter out and see if I did have power to the distributor with the key on and with the engine cranking over. Then go from there.

[joedoh]

did you use a relay on the condenser fan or hook it straight to ignition? condenser fans draw 25-30A and you should use a relay, a standard automotive type will be fine.

if you havent used one and want to know how to wire it,

pin 87: heavy fused (10-12ga, 30A fuse) from battery

pin 85: wire from your binary or trinary switch, could be + or - trigger. can be lighter ga wire, 85 and 86 are the low current "switch" 87 and 30 are the high current contacts.

pin 86: the opposite of the wire from your binary/trinary switch, so if pin 85 is a - trigger you would put + on 86. if you trigger on 85 is positive (like what triggers the AC clutch) you would put - (ground) on 86.

pin 30: + out to condenser fan. this will be 10-12ga like the 87. you will ground the other wire on your condenser fan.

and dont use the pink (ignition) wire as a supply for any of these wires.