Just an FYI.... Always keep the high side manifold valve closed. Draining, evacuating, and recharging is all done on the low side.


Your image of the manifold set above, shows high and low side pressures equalized at ~77psi. That tells me there is refrigerant in the system, your ambient temperature was ~77 degrees, and the compressor was not running. Is that correct?

 

I was just following this procedure:

The temperature was ~72. The engine was not running at the time the pic was taken. I only started up the vehicle to run the compressor after a significant amount of time had passed and it seemed that a static system was not talking in any more refrigerant...thought I'd need to have the compressor running to draw it in.

 

If you don't operate the AC while charging, the system pressure, and the refrigerant supply, will stabilize at ambient temperature/pressure, long before the system is full.

When you are ready to charge it, make sure the high side manifold valve is closed, and the low side valve is open. Start the engine, turn the AC on MAX, and the blower to high speed. Start adding refrigerant. When accumulator pressure reaches ~42psi, the compressor will come on and the low side pressure will drop, the clutch will start cycling, and the system will pull in the refrigerant. Shut off the supply when the correct amount has been charged.

 

I believe this is exactly the process I followed. Maybe I was being impatient but after 30 minutes it appeared the system drew in maybe 0.1 ounce. That just doesn't seem right. How fast should the system normally draw in the refrigerant?

 

Ambient temperature, and the temperature of the refrigerant, are both factors in how long it takes to charge. At 70F it usually takes 30 to 40 seconds from 29.4" vacuum to fully charged.

 

It sounds like there's something majorly wrong then if after 30 minutes it barely took anything from the can. Any ideas?

I'm wondering if it's the manifold gauge set ... although it doesn't explain why the high pressure gauge was showing a reading if the blue low side hose is plugged up.

 

When you connect the hoses to the vehicle, and tighten down the core depressors, the gauges are exposed to system pressures whether the valves on the manifold set are open or closed. When you open the valves on the gauge set, it opens a passage from the valve to the center hose. If both valves are open, high side pressure will enter the low side... not good. The high side gauge is for monitoring pressure ONLY. That's why the red valve should be closed all the time. When you're done charging, disconnect the hoses from the vehicle, and open both valves on the gauge set. Pressure in both hoses will exit the yellow hose. That will relieve pressure from both hoses, (not good to leave pressure on the gauges and hoses while not in use).

In the video, at 11:28 he removes the yellow hose from the supply. The hose is now exposed to the atmosphere, (vacuum is lost) and sucked in ambient humidity. If you use one of these on the center port of the gauge set, it makes transferring from evacuation to charging a snap, without loss of vacuum, or the introduction of humidity. http://cdn3.volusion.com/mwtkx.qaznd...s/311116-2.jpg


I would check your hoses for Schrader valves. There is no need for them and could explain why you can't charge the system. During evacuation, you might be evacuating the hose only. During charging, it would not allow refrigerant into the blue hose.


Just an FYI: When you tighten the core depressor on the coupler, only tighten it until the gauge shows pressure. If you over tighten it, permanent damage to the core will occur, and it will not seal when you remove the coupler. The type of coupler he used is superior to the "automatic" ones he talked about, avoid them.


When evacuating, maximum achievable vacuum is 2 atmospheres, (29.4") so don't expect to see 30", ain't gonna happen with any evacuator. Evacuation needs to be a minimum of one hour, or don't bother. The longer the better, overnight is good. The point of evacuation is to remove moisture. The moisture must boil before it can be removed as a vapor, and that takes time. 30 minutes is not nearly enough.

 

Your explanation is the same as my understanding. The mystery remains that the refrigerant is not entering the system in any quantity noteworthy. I think I'll go pick up a new set of manifold gauges as who knows how these rental AutoZone gauges were previously used.

Any thoughts about placing the 12oz can of refrigerant in warm water to speed up the process? You'd think 100 degree water would help when the ambient temps is in the 70's. Have to be careful not to let the top of the can get wet and possibly introduce moisture when changing out cans.

 

Check both ends of all 3 hoses, and the gauge set connections, for Schrader valves. Let me know what you find.


When ambient temp is 70F, refrigerant pressure in the can will be very close to 70psi. Low side pressure cycles between 22psi & 42psi. Refrigerant in the can will enter the system and equalize at 22-42psi. Heating the can is dangerous and not necessary. Let physics work for you, it's much safer

 

Nope, no schrader valves on either side of the 3 hoses.

The other thing I was wondering about is the PAG150 oil ... if it is viscous enough to form a barrier (in large undistributed quantities) in certain areas of the a/c system that low pressure refrigerant can't get past. There's 3 oz in the pump (factory) and I added another 1 oz to the suction side of the pump. 2 oz went into the input side of the accumulator, 1 oz went into the evaporator and 1 oz on the input side of the condenser.