AC Pressure Switch for r134a?
Ryanthegreat1
Wagonist
Fun times with AC when the cold weather rolls around....
I have converted to r134a and had great results all summer but now that the weather is cold I am having issues with the AC not cycling. I think I have figured it out, the stock AC pressure switch shuts off below 33psi and at near freezing temps the vapor pressure of r134a is right around that or below.
Is there a pressure switch for our application that is better suited for the pressure range of r134a?
More details because science.
Vapor pressure at 32F
R12 = 43.87psi
R134a = 27.7psi
So adding more refrigerant won't increase my pressures.
I might be able to swap in a 94+ pressure switch designed for r134a, they have a low limit of 28psi. That just gets me to 32F. Beats the 38F I would have to be at now.
I have converted to r134a and had great results all summer but now that the weather is cold I am having issues with the AC not cycling. I think I have figured it out, the stock AC pressure switch shuts off below 33psi and at near freezing temps the vapor pressure of r134a is right around that or below.
Is there a pressure switch for our application that is better suited for the pressure range of r134a?
More details because science.
Vapor pressure at 32F
R12 = 43.87psi
R134a = 27.7psi
So adding more refrigerant won't increase my pressures.
I might be able to swap in a 94+ pressure switch designed for r134a, they have a low limit of 28psi. That just gets me to 32F. Beats the 38F I would have to be at now.
Comments
Today being a few degrees warmer the AC is working perfect.
Stupid Pacific North Wet and being cold and damp and fogging up the glass.
Found a Chinese direct reseller for AC switches, looks like Honda stuck with the same thread pitch and switch design for a decade or two. 3/8-24 UNF male is what I am finding. The newest stuff looks to be metric.
Might go to the wreckers and see if I can find a switch from a 94+ car. Then I can get the plug for the sensor as well because those changed each generation.
But then that leads to the question of how do you charge AC when it is cold out and the r134a temperature pressure charts only go down to 65F. Might have to just live with no AC in the extra cold temps until spring.