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Harbor Freight has a gram scale for next to nothing. On my last fill I measured each can prior to dispensing refrigerant, marking full weight on the cans with Sharpie. Getting refrigerant out of the can is made more difficult because can pressure drops precipitously as the gas evacuates. Overcoming the pressure loss is pretty easy, just use a small bucket of not-quite hot water to keep the can warm. Others have used a towel wetted with warm water — I found towels got cold too fast. From empty, I empty a can into the system, then weigh the empty can. Repeat until I have input the appropriate amount.
When the compressor turns on, the low side pressure rises rapidly and the high side pressure drops. When it turns off, they rapidly begin to level out, low side drops, high side rises. The compressor is only staying on for a second before shutting off. In the video, low side is on the left
Let's get back to the basics:
What should happen when you evacuate and then charge, even with a 12 ounce can, is to get enough charge into the system so that it will run. Some on the Forum say they must jump the compressor to pull in charge. I have never experienced that whether using cans or a dial-a charge (this is before we had refrigerant recovery/recharge systems).
A functioning system, even with low charge, will pull down the low side and pump up the high side. Yours is doing the opposite. I suggest you disconnect the high side gage set hose from the system and try to charge again using just the low side.
If that fails, it makes me wonder about your custom hose set. Is it plumbed backwards to the compressor? Did some one put the wrong high and low side fittings on the custom set?
You have a Sanden compressor. Is it a variable displacement or fixed displacement?
I spoke with a local shop, he said something that I have wondered: sometimes the little 12oz cans of freon don't have enough oomph to charge. He suggested it may just need their machine to do the charging. I am leaning that way too, because I just can't figure it out! I will continue to monitor this thread and take any advice before I get a chance to bring it in to a shop.
That statement is not true. Any Pressure, whether it be air or refrigerant, wants to equalize, so the high pressure in the freon can goes to the low pressure side of the system. There must be a difference in pressure between the freon can and the low side pressure port. The difference in pressures is what transfers the fluid (refrigerant). The "machine" does not have a pump to pressurize the freon into the system.
Thanks for sharing the video you're definitely doing things right by checking for blockages and pulling a vacuum. The symptoms you're describing (low side pressure rising quickly, high side dropping, and rapid cycling) often point to a restriction in the system. I’d double-check the orifice tube sometimes they get installed backwards or can be partially blocked even if air seems to flow through. Also, make sure you're charging with the correct amount of refrigerant by weight, not just pressure readings. Hope the shop visit helps, but you’re already ahead by narrowing it down this far. Good luck! delta executor apk
Last edited by welldora; Oct 19, 2025 at 06:49 AM.
Your comments made me re examine if the lines were crossed. It is acting EXACTLY as if the low and high side lines are crossed, but I kept dismissing it for a few reasons (here come the excuses for my lack of knowledge) the OEM lines at the compressor are the same diameter. My new compressor has two different diameters ports mounted to the side of the compressor (see photo). I figured, the rear port went to the low side and the front port went to the condenser. But no, I believe they are supposed to criss cross. Doesn't make sense to have them cross like that.
On the plus side, no need to go to a shop and I can have the lines extended in five minutes. I may get my A/C working yet. Thanks all. I'll close this out when the A/C is nice and cool.
The high side is the small diameter, rear port , which is where I have the low side connected too.
Last edited by Eleven Bravo; Jul 1, 2025 at 12:26 AM.
Your comments made me re examine if the lines were crossed. It is acting EXACTLY as if the low and high side lines are crossed, but I kept dismissing it for a few reasons (here come the excuses for my lack of knowledge) the OEM lines at the compressor are the same diameter. My new compressor has two different diameters ports mounted to the side of the compressor (see photo). I figured, the rear port went to the low side and the front port went to the condenser. But no, I believe they are supposed to criss cross. Doesn't make sense to have them cross like that.
On the plus side, no need to go to a shop and I can have the lines extended in five minutes. I may get my A/C working yet. Thanks all. I'll close this out when the A/C is nice and cool.
The high side is the small diameter, rear port , which is where I have the low side connected too.
Wait....so this is a custom setup. Why are the lines separate and connected on the side of the compressor?
Wait....so this is a custom setup. Why are the lines separate and connected on the side of the compressor?
This is how the Sanden compressor is. The kit is from Dirty Dingo with the brackets etc. Here is the compressor with the block off plate for shipping, as it's shipped with the proper amount of oil
Last edited by Eleven Bravo; Jul 1, 2025 at 10:47 AM.
This is how the Sanden compressor is. The kit is from Dirty Dingo with the brackets etc. Here is the compressor with the block off plate for shipping, as it's shipped with the proper amount of oil
One way to determine which is low and which is high side, is to turn the compressor by hand in a CW direction while facing the front of the pulley. Cover one of the ports with your finger while turning the compressor, the low side will suck your finger in and the high side will push your finger off. I think you have determined this already but this will tell you for sure.
