348 HVAC ECU

"No nothing" sounds like the ecu isn't getting any power. I'd check it's connector again. If you still have the passenger side console kick panel removed, try wiggling it's electrical cable.

 

[Edit] Not sure... appears to be straight through the front bulkhead.
.
Image Unavailable, Please Login

 

However, according to the wiring diagram, there are two connectors between the dashboard harness and the a/c system. Connectors 14 & 21.

 

Dielectric grease is an insulator. Did you put it on the connector pins by mistake?

Many of the wires don't go through 14 and 21. I'm not sure which is the power wire though. It was mentioned recently that the white wire (on pin 26) was for background lighting power. There is also a procedure for fixing up the (internal) plug pins in the HVAC control panel mentioned in this post:

Dim Clock and A/C LEDs

Here's the F348 HVAC diagram:

F348 HVAC Wiring Diagram

 

Looking at that wiring diagram, it seems that pin 1 is the power pin for the HVAC Controller. If you still have access to the plug, maybe you could check for voltage there, John?

If no power....
Pin 1 goes directly to the relay socket for the Evaporator Fan Relay on a brown wire (See "68" on the wiring diagram). The brown wire is visible in the photograph Wade posted. No plugs involved. Power doesn't go through the relay, but goes directly to the 30 Amp fuse. When you checked the fuse, did you check there was voltage (the fuse is connected directly to the battery bus bar in the passenger footwell)?
If there is power at the fuse, move on to the relay socket and check for 12 volts on socket "30". That is, pull the relay to do this.

 

I wouldn't put any dielectric grease in a delicate multi pin connector. The pins related to power supply and illumination:

Image Unavailable, Please Login

 

The wiring on pin 3 is a little tricky to follow. I see ignition power goes via Relay B in the passenger footwell, Fuse 6 (also in the footwell), HVAC connector (14), Compressor Clutch Relay socket (67), Evaporator Fan Relay socket (68), then to the HVAC Controller. I think Relay B and fuse 6 should be ok. You'd have a lot more things not working if these were faulty.

 

I suggest you clean out the dielectric grease from the yellow connector as best as you can. There could be some misconceptions as to how and where the dielectric grease is used. It is not recommended to be used on connector contacts. It does not improve contacts between pins and sockets but it may reduce the connectivity (being an insulator), especially in connectors with small pins and with weaker contact pressure. Dielectric grease should only be used on sealed connectors and on their rubber gaskets/boots and the gasket mating surfaces to improve sealing.

 

I had a few issues like you describe. The yellow plug was the problem as the wiring loom came in at an tight angle which put the plug under tension and it didn't seat properly. Relieved the tension and its been fine since. Worth a look. Mine is a RHD so loom position may be different.

 

Yes, especially on the early cars (HVAC controller w/ white backshell). If the connector cable ran in the opposite direction (flipped 180 degrees) the strain would be completely eliminated.

Photos show OEM configuration.
.
Image Unavailable, Please Login Image Unavailable, Please Login