I have a 99 expedition now 5.4 ltr, heat does not work nor does the a/c, also has rear a/c and **** fully loaded 4x4, The compressor never clicks on I was thinking a relay??? but I dunno the heat does not work as well, I have a headache on this thing can someone lend me their brain?????

 

I tested the voltage that clips on to the compressor it had a reading of 0.03?? and also did a jumper wire as well the compressor never clicked on, so maybe this will help me narrow the problem down, oh btw it has the digital controls.

 

Check for wear on the ac clutch too much and it won't pull in!
Heater could be the blend door issue.

 

thanks i'll check it out, but now I cant even get the blower to come on in the front I checked all the fuses and even ohmed them out to make sure they were all good, I can hear a click like a relay coming on but nothing blows, the rear blows but not front. this thing is giving me a migrane!!