Newbie here and I thought I just got a greatest car. I just inherited a 2000 1.8l protege and the a/c is causing something I have never seen in the past. First off, the 1.8l engine runs, drives and idles great

When you turn the a/c switch and fan on the engine intermitantly cuts out, then recovers until the next cut out. These are not long enough to completely stall the engine though. When the fan is in position 1 it will happen 2 or 3 times in a row and then you have to wait for it to happen again say 15 - 30 seconds. As you turn the fan speed up the frequency of the problem goes with it. Once its on level 4 it is almost constant.

It is not a fuel issue and it doesn't behave like a bad coil or spark plug does not coping with the extra load. It is like you are turning the key on and off.. When the ac switch is turned on the fast idle works fine. Turn the ac switch off and turn the fan on 4 it's fine.

I can only think of three choices. The extra electrical load from the ac and fan is tripping something like a thermal fuse/relay on the main power? Maybe there is a fractured fuse or relay overheating and breaking contact. The crankshaft sensor is losing its signal but I can't really explain that one.

I hope someone has seen this before?

 

I know you have all been waiting for the fix to this weird problem.

It was a faulty coil.