74 is the 1st modern one I think, integrated system that is, thermostat line I am thinking of is tied to a box that is mounted to the cold---------hot lever IIRC.

that line just sticks into the fins of the evap.

pressure looks good, oil injection went well pulling vac later.

Edited February 14, 20178 yr by Dave WM

hmmm looks like I may have a shaft seal leak, hold pressure just fine but leaks down in a vacuum..

 

Well here's a philosophical question for you... The system is normally under pressure, not vacuum. So if it hold's pressure in the correct direction (higher inside the system than out), is it really the end of the world that it won't hold pressure the other way (vacuum inside the system).

Many seals are designed to hold pressure in one direction only. Did they do that on the A/C system?

Like I said... Just enough to be dangerous.

FWIW, when I redid my oem system, it held vacuum pressure overnight.   The compressor shaft seal is a very common leak source.

I was fortunate that in my documentation I received with the car, the original owner upgraded the AC to R134a and the Nissan dealer installed a new compressor & evaporator.

Here's my evaporator from the 74. I assume the thermostat you were talking about is the device on the lower left of the pic?

I assume this is the thermostat you were talking about:

yes that's it

Cool. Thanks. I don't know how it hooks into the temp lever yet as my non-AC control head doesn't seem to have provisions for attachment, but I'll figure something out. So they used that device to regulate the evaporator temperature by turning the compressor on and off?

So what are you going to do about your vacuum test results? You going to replace the compressor front seal and see what happens?

prob just replace the compressor with a spare I have.

On you thermostat, IIRC that hard wire on it somehow ties into the slider for heat cold.