What year is this AC system
 

My truck is a 77, but this may be a 78 or newer style. Anyone know for sure? Thanks!

Re: What year is this AC system
 

That looks like my 74 C10. Possibly several years were similar.

Re: What year is this AC system
 

Supposedly the wiring changed sometime around 77 -78, I'd like to order a new harness and want to make sure I get the right one. Thanks for the info.

Re: What year is this AC system
 

The plumbing looks like my 75. Not sure about the electrical gizmo just under the blue sticker. Did someone move the 'too cold' pipe sensor from the normal location to there?

Re: What year is this AC system
 

Not sure what if anything was changed, my truck is a 77, but has a 78 AC cab, the AC harness has been cut/spliced, trying to figure out which harness to order a 77 or 78? They have different parts #'s in the Lectric Limited catalog. From the catalog 1978 AC harness -2nd design: air conditioning thermostatic switch mounts to evaporator near receiver/accumulator.

Re: What year is this AC system
 

usually the compressor is long cylinder on older ones the newer is the thinner one

Re: What year is this AC system
 

A pic of the wiring on my 75. Top is the fan relay. Under that is the thermostat cold cut off. To the right side is the high pressure switch.

Re: What year is this AC system
 

Looks like the thermostatic switch is on the low side line. Hard to tell from your pix.

Re: What year is this AC system
 

Here's a few more.

Re: What year is this AC system
 

Some butchery going on there

Re: What year is this AC system
 

Yes, most of the truck was cobbled when I bought it, just about got it like it should be, but the AC is a guessing game. I'm going to pull the evaporator soon and see what part # it has on it. that may help me determine what year it is.

Re: What year is this AC system
 

Anyone know if the 1978 1st design and 1978 2nd design AC systems use the same dash controls? Maybe the only difference in wiring is under the hood? If so, I'll change everything over to one or the other designs.