Ac cycling switch.

[Danec71]

Here is the basic parts to my system. I have a different pump for some reason then you would usually see on most trucks I think. Anyway I am not sure if I am suppose to have a cycling switch on my dryer or not. It didn’t come with a thread part to put one on. It does have a cap you can see on the picture. Am I suppose to take that off and put a switch there. Or does this sustem not have one. Also on the thermo switch. You can see how it is mounted on the picture. Question is where is the long probe thing suppose to go into or wrap around. As you can see it’s shoved into the box. And is this all suppose to be isolated from heat. So am I missing some part or is something in the wrong location. Seems to cool alright. But the compressor clutch never turns off. One last thing. If there is some info on how to adjust the 2 screws on the thermos switch. Thanks. Can’t find anything on this system and not really sure if it is factory.

 

[RonD]

Welcome to the forum

No, for sure, not factory, anyone's factory, it is pieced together from older AC systems

The thermostat, 9533n406 rev A, is just a generic AC thermostat, I would think that it probe should be on the Evaporator, inside the box, and it would shut off compressor when it was cold enough(35deg) then turn it back on when hot enough(45deg), would need to be touching metal on evaporator

Does either compressor clutch wire match a thermostat wire?

The thermostat is what turns compressor on and off, not a pressure switch(cycling switch) from what I can see
So its either hook directly to clutch or it activates a separate relay, follow the wires

And there should be a switch inside the cab to activate AC to begin with, you didn't mention that

You could certainly burn out the compressor if system ran dry, leaked, with no pressure switch to shut off compressor when level got to low
There may be a pressure switch on the compressor, look at the wire on it

 

[Danec71]

Yes there is a button built into the heater control panel. Like it is factory. Then of course the big box under the hood for the evaporator. Not sure if there is a wire that is matching one plugging into the compressor that’s the same as the thermo switch. Both those wires disappear into the firewall under the glove box. I assumed they were probably going to the button on the panel inside. But I can look if there is a matching color. I guess my biggest thing is finding out the proper way to mount that thermo switch and we’re the probe deal is suppose to go. This is how it was when I got the truck. Ac wasn’t even hooked up. So I don’t know if it is even close to right. It looks like it should have been factory installed but that compressor throws me off because it is nothing like the ones I have seen in similar year trucks

 

[Danec71]

No pressure switch on compressor.

 

[RobbieD]

Welcome.

Your AC system isn't factory installed, and I can't tell if it's an aftermarket kit, or a system just cobbled together from aftermarket parts. I "think" what you've got is a cycling clutch system, with an expansion valve and a thermo switch. See the attached diagram; it's from an old tech manual, but a better understanding of the system may hopefully help you out in working on it.

Your third picture, the expansion valve sensing bulb should be attached, with a clip, onto the metal part of the other, larger low pressure line, where it goes into the evaporator housing. Once attached the sensing bulb is usually wrapped with a sticky cork-impregnated tape.

The thermostatic switch, your fourth picture, I don't recall ever seeing that type. In what I used to install, these were usually a dial control and part of the operator's AC controls. As your picture shows, the sensing probe goes through the hole in the evaporator housing, and the end should be inserted into, and touching, the evaporator fins. The thermo switch does look like it might be a newer component, compared to the rest.

Again, I'm not familiar with that style thermo switch, but you could try adjusting it. I'm guessing, but I would think that adjusting the "cut out" should cause the compressor to turn off when the evaporator gets too close to freezing. When the evaporator temperature raises to reach the setting of the "cut in", the compressor is turned back on. Unless you can find instructions for that switch, it'll might take some experimentation to dope out how the setting controls actually work.

Good luck!

 

[Danec71]

Here is a picture of the controls. Is this a factory setup with the ac switch. I think I may have it figured out. One thing though I did replace the orffice tube with a stock one. But I am using 134 instead of the r12. From what I have heard you are suppose to switch to a larger one when using the r134. Is this true. If so I ca replace that and just figure out this thermonswitch and I should be good

 

[RonD]

The Panel in cab and evaporator housing(heater box) in engine bay may have been stock, or pulled from a stock AC Ranger of similar year
Condenser(in front of radiator) may also be stock or pulled from stock Ranger
But the rest of the system is not stock

 

[Danec71]

The Panel in cab and evaporator housing(heater box) in engine bay may have been stock, or pulled from a stock AC Ranger of similar year
Condenser(in front of radiator) may also be stock or pulled from stock Ranger
But there rest of the system is not stock

Great. Good to know. Thanks. This info will be good for finding parts or info

 

[RobbieD]

I'm confused. If the system has an expansion valve, it shouldn't have an orifice tube. They are two different animals, either of which can do the same job.

 

[RonD]

+1 ^^^

Yes, expansion valves were more expensive, and often externally adjustable, making them more expensive, lol
So most, if not all, car makers switched to Orifice tubes