I spoke with someone and my hypotheses was right. There is no bulb for temp sensor but it is actually built into the switch itself. I will take apart my parts mark IV soon to look it over.

I hooked the brown wire up as the fan. Still not sure what runs to to the compressor side.

This is the common method for wiring most all aftermarket evaporators.

Okay. So usually on aftermarket underdash ac the red wire to fan goes to the ignition, green wire goes to binary or trinary switch , then to compressor. This old Mark IV has no thermostat. I recently bought a service manual for Mark IV ac. I found the wiring diagram. (See pictures) When I look at th...

Consider a V5 or V7 variable displacement compressor, it is the modern equivalent to a POA system. The wiring is very simple since you just need to turn the compressor on and let it run. A high-low (trinary) pressure switch should be installed in the high side line to protect the system against ove...

bohica2xo wrote:David:

Are you doing a wagon as well?

Yes. 58’ yeoman. Have a bunch insulation to add to it.

[quote="bohica2xo"]Sorry we hijacked your thread David. A friend of mine is building a 1959 Chevrolet station wagon, and he is doing just what you are - adding an original knee-knocker. I am trying to convince him to put an evaporator in the back too. We are stumped on exactly what that sh...

It’s nice to use your parts car as a mock up.

Boar with bad vision took his last step as he walked right up yo my pickup a few days ago. Dad's 54 chevy had the square Mark IV with a long louver across the top front. Compressor drive belt had to be removed in winter before adaption of a clutch. Temp control by knob on suction pressure regulator...

For Ice n tropics would it be beneficial to look for an older mark IV allegro like the one pictured vs using the newer repop vintage air mark IV? I know you said the older ones had more BTU's. I know I've read others using an older evaporator with newer sandon compressors, condensers, lines etc and ...