Automotive Air Conditioning Information Forum

I'm fairly certain I know the answer to the first half of my question. But I'm going to ask to confirm.

When adding freon or leak detector to my vehicle's AC system does the AC compressor clutch needs to be engaged either while or before I'm adding?

I believe the answer is yes so assuming that is correct, then what do I need to do if my AC compressor clutch will not engage and start spinning?

JonLock88 wrote:When adding freon or leak detector to my vehicle's AC system does the AC compressor clutch needs to be engaged either while or before I'm adding?

Not if you add the UV dye BEFORE you evacuate and then add freon. And same if your vehicle uses R134a. Or if you add a can of refrigerant containing UV dye as the first can AFTER evacuation (do NOT add any sealer !!!).

There is a special tool/fitting that can add UV dye when there is already refrigerant in the system.

JonLock88 wrote:what do I need to do if my AC compressor clutch will not engage and start spinning?

You diagnose whether the pressure is too low to activate the switch, or if there is a different cause.

Well, the AC will not engage (unless I use a jumper from the battery to terminal 86 of the ac relay in the fuse box under the hood. Then the clutch "attempts" to engage, once it is in the "attempting" stage, I can tap it with a wooden handle or wrench or something inward and then it engages and starts to spin). I just hooked up my gauges. And the low side reads 19-20lbs and the high side reads 0. This is with the vehicle off. I can crank the engine and turn ac to high and do all that, but it doesn't change because as I said before. The clutch will not engage. I have only done the jumper trick a couple times and only while I attempted to add freon to the system due to me being afraid of damaging something that isn't already damaged.

So, any advice on what I should do next?

Ok, so this is what I did.

I did the jumper trick. Started the ac compressor. Added a little freon and then I dye. Let it run for a bit. After a few minutes I started hearing a hissing noise coming from somewhere around the accumulator (round thing on the back left under the hood near the low pressure port). And then the engine started bogging down and trying to die. It probably would have if I hadn't unplugged the jumper (still tried dieing after I was unplugged too) and then killed it to avoid and possible damage. And then I cranked it back, and with the ac on it tried dieing again but when it was off it ran fine. Also, the high pressure side never gained much pressure at all. But a very slight hissing also started coming from the port, which I then plugged the gauge into and it didn't read anything still. Not sure if the port continued to leak after unplugging the gauge because by then I had killed the engine. With the compressor NOT running and the engine running I didn't hear the hissing from the accumulator. As for the dye I added. I either didn't run it long enough or it just wasn't able to make it through the system for whatever reason.

Anyone have any ideas as to what could be going on?

And the ol' jumper wire kills another compressor!

The low pressure switch keeps the compressor from running when there is not enough refrigerant in the system to circulate oil.

Your compressor is done. The condenser is now contaminated with debris from the compressor.

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