AC Dead After P0306 Repair

I have an 05 Expedition with 5.4. The motor was shuddering and throwing a code P0306. What I did to fix the problem was to replace the spark plug on #6 cylinder with a new Motorcraft SP515. During this replacement I noticed that the connector for the fuel injector for that cylinder was a little bit dirty. The original spark plug that I removed actually looked in very good shape. The motor has 125,000 miles on it. Plugs had never been changed. After removal and replacement of plug I cleared the code with my OBD II scan tool. This solved the shuddering and no codes have come back again. The only problem is immediately upon solving this problem, my AC quit working. It wasn't a slow fizzle, it just immediately died after I reset with my scan tool. The AC has never given me any problems in the past, not like it had low refridgerant. It went from ice cold to dead after resetting the code. I have checked fuses #11 #13 #18 in side kick panel. Did not replace them, but visually the fuses look good. I know in the engine compartment there is aux fuse panel with a clutch relay in it and also a diode. Have not checked those, but really don't have the tool to see if those are bad or not without putting in new replacements to see what happens. Haven't found anything on the forum talking about if there is a master reset for the AC system, something that I'm missing, but doing some Google searches I have seen that people have had problems with their AC conking out after removing the coil on one of their spark plugs for a spark plug removal. Is this something that happens, or is it a freak incident? Any help in this matter is much appreciated.

You say the fuses looked good Please explain what you mean by "LOOKED GOOD"

The metal ribbon in fuse #11,13.and 18 was still intact, I just replaced all said fuses for good measure, plus also replaced the ac relay up front in the aux panel. No luck, ac still blows warm air.

Although the fuses look good can you tell me what the voltage was going into and out of the fuses.


In other words the best way to check a fuse is by a check for voltage The second best way is to use a ohm meter Looks can be deceiving.

If your expy doesn't start would you juat look at the battery and say it looks good or would you test it. Same applies to fuses.

Also check the following fuses 116, 13, 11, 32 and 8

See the attached link

http://www.expeditionforum.com/f16/fuse-testing-101-a-24587/#post200023

The way I normally check fuses is first to pull it, check to see if metal ribbon has shorted out, if it looks good then check for resistance with an ohm meter. If that checks out, then pop the fuse back in and check for voltage on test probes of the fuse. So far, all said fuses have checked out. Normally, when I say a fuse is good, I don't explain the process of every step I've done. I don't find it necessary to say that. I figure people either know how to check fuses and if they don't I don't even worry about them. Sometimes you just let things go if people don't understand the proper way to do something instead of pointing out every last minute nuance of the procedure. Not that I'm still not able to learn. Any help figuring out this issue is still much appreciated.

Back to my original question, have there been any issues with the AC conking out after changing coils which is the situation that happened to me.

First of all the METAL RIBBON doesn't short out It opens up. You only stated that you looked at the fuse You didn't mention anything about checking voltage so I had no way of knowing if you did or didn't. Voltage is what makes things operate not good looking fuses. If no voltage then no A/C.

I also mentioned about checking a few other fuses which are part of the circuit But you haven't mentioned that you checked them or not. Without any replies I have no idea of what you checked.

Do you have electric prints of the circuit.

But being you know how to check the fuses I will step away as I don't think you would appreciate my help.

Had you checked for voltage first You would not had any need to pull a fuse as you would have known that you had input and output voltage.

Hope you solve your problem

So far the fuses that have been checked and replaced, are #8,11,13,18,32,116, and the ac relay in the front aux panel.

I am totally curious. Why would you replace fuses that checked good??
And again you mention nothing as to what the voltage is or was. Or if you have prints so you can check the circuit.

I will have to get back to you on the voltage reading on each fuse, have them written down, out in the shop. I replaced each fuse just for peace of mind, and I do not have a map of the complete circuit.