Converting factory AC to use R134a

[ricachon7]

I know this is a VERY old thread. Sorry and I am reviving only b/c I am not able to find information on wiring the hi-lo switch in a 70 C10 set up with factory air. I understand one wire goes to the compressor clutch but can't figure out the other wire. Does it go to the compressor switch behind the selector box in the cab?

[dmjlambert]

I don't know what a hi-lo switch is, but here is the wiring diagram

[kwmech]

I agree, you'll have to brush up on your terminology. When I converted my 69 to 134a, I also went with an updated cycling system and eliminated the POA valve. I also went with a newer style compressor that matches the one in my 91 Suburban, only it has the V belt.

[ricachon7]

Excellent! Thank you kindly for the diagram. I failed to mention that I have swapped in an ls engine and installed a Sanden compressor. I have all the original components there. I will be updating the POA valve, condenser, dryer and hoses. I've seen a lot of ppl put a binary switch in on the dryer. One wire goes to the compressor but cannot find information on what the second wire (off of the binary switch) goes to. It was my understanding the binary switch is the same as the hi-lo switch AND cycling switch. Perhaps these are not all the same and that might be my confusion. Thank you for your input.

[body bolt]

The switch is typically in series with the compressor clutch power; in the schematic that would be 14DG.

[dmjlambert]

I think it matters what you mean about "updating" the POA valve.

If you are talking about rebuilding the POA valve and recalibrating it to work with R134a, then you would not need to cycle the compressor and that means no binary, hi-lo, or cycling switch. The compressor doesn't cycle.

If you get rid of the POA valve and put in a POA valve eliminator, the POA valve eliminator has 2 terminals on it and you wire that up to interrupt the power going to your compressor, and the compressor cycles. So the wiring would be as shown in the wiring diagram, except you would run the compressor wire to one terminal the POA valve eliminator, and the other terminal on the POA valve eliminator connects to your compressor. That's the way mine is wired. The POA valve eliminator on mine switches the compressor off if the pressure is too high or too low.

My dryer came with a plug that can be removed and a switch to install in that plugged port. I did not use it and Original Air, who sold me my A/C kit, told me I don't need to use that, just wire the POA valve eliminator in-line with the compressor wire.

[ricachon7]

TheBandit has an excellent video on youtube (https://youtu.be/jNUb-GDWz4Y). I was planning on doing what he has done except I do not have an ambient temperature sensor. His setup hooks up the ambient temperature sensor to the compressor clutch. I don't need that since I live in AZ but I still need to trigger the compressor. I will post a diagram to show what my setup should look like and ask for feedback. Based on what others have said about problems with the POA eliminator valve, I am inclined to rebuild and recalibrate the factory POA. That being the case, I wouldn't need a cycling switch but I still need to wire the compressor in line with 14DG as the trigger, correct?

[dmjlambert]

14 dark green wire sends power to the compressor clutch. I don't know if I would call that a trigger, but it does turn the compressor on when the A/C is switched on. In the factory setup, the 14 dark green wire gets 12V when the key is on, the blower is not off, and the middle slider on the A/C control panel is all the way to the left.

[ricachon7]

Thank you!!

Here's what I drew up. This is my understanding of the wiring and the routing of hoses. Does this appear correct?

AC COMPONENTS.pdf

[dmjlambert]

Looks pretty good to me. Here's the factory setup from the 1970 service manual.

[YellowK5]

For most later Generation AC system the hi low switch is a hi pressure cut out and low pressure cut out for the compressor..Hi pressure will/can blow up the system or burst a hose(no POV valve) and low if you loose the Freon so the compressor wont burn up..

[ricachon7]

Thank you, dmjlambert!!

I believe I understand now but I just want to make sure I do.

Can I have the factory air set up just as shown on the diagram but instead of using the original type of compressor use a Sanden type and it works just the same?

Do I not need to add a binary switch?

Do I understand correctly that I do not need to be concerned about the compressor cycling if I keep the POA valve?

[dmjlambert]

That's my understanding but I don't have much experience. If you don't hear others chime in you may want to make a separate new thread.