No A/C. The EATC won't engage the compressor.

[thejkkidd]

Compressor not engaging. I recently purchased a 97 limited 5.0, the previous owner was a complete idiot when it came to any work on any vehicle. I claimed the EATC head unit went bad and bought used unit that as I discovered was a 98 unit. I located connectors and rewired it to the existing harness. Everything works properly except I can't get the compressor to kick on. I tested the compressor by running direct to it off the battery and it kicks in. Does anyone know the correct proper connections for a 98 eatc head to 97 eatc wiring?? Also, he had switched out all the relays so I am not sure of what correct relays are supposed to be used in the Power Dist. Box. I live on the Mississippi Gulf Coast and really need that A/C!! Thanks!!

 

[BrooklynBay]

Welcome to this forum! I've moved your thread into the A/C & heater section. Did you check the low pressure cycling switch, and the charge in the system with a manifold gauge set?

 

[thejkkidd]

The charge is a little low and was in the process of checking the switch when I received your reply. I am still concerned about the wiring conversion however. The 97 head unit had 1 less wire than the 98 head did and am confused as to what wire(s) is actually for the compressor. Anything on which relay is correct for the compressor?? Thanks for the help!!

 

[BrooklynBay]

You should try to get a hold of a schematic diagram of both years.