No you dont want to charge on the pressure side of the system it would be around 200psi if its full. When the you have it set to max ac and vent on full does the compressor cycle or is it staying on and do the accumulator that part you added coolant to and the evaporator inlet line which is the line that goes into the firewall below the accumulator fell close to the same temp or is is one froze over and the other hot.

 

The silver canister at #1 is not cold/cool at all. Top and bottom it's very warm. What I'm sure is the compressor #3 is running. The pressure is still sitting around what I left it at. I did some driving around today and turned the A/C to it's max and the pressure is the same which tells me it's not leaking but though I drove a fair amount it's still putting out nothing but hot/warm air.


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If you leave the system for say a half day or so what is the pressure at the low pressure port before you start it up. It should be like 100ish because the pressure will be equalized between high and low. Both the things that are warm should have been cool to frosty if the compressor is working right, either it isnt compressing or you have a plugged line.

 

When you say 100ish, where would I get this reading. I think the gauge I have only connects to spot #1 in the image which is where I have 38psi and I don't think it will connect to #2.

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Just to be doubly sure, you can verify that the center portion of the compressor is turning, not just the pulley portion, correct?... As stated earlier, the compressor has to be turning. You should see a pressure difference from when the truck engine is off and when it is on with the compressor running.

 

The pressure would be 100ish at the low pressure port that your gauge goes onto if the a/c hasnt been on for hours. Its when the low pressure suction side 30ish equalizes with the high pressure 200ish side. If you can only get 38 when you do this after the trucks been off for hours than the system is far from full

 

OK, so went out and took another look at the compressor. The belt and wheel in the image is turning. The center bolt in the image was not spinning. Should this be spinning?

 

takes 47 psi to turn on compressor- you have 38 static pressure which is about 2 ounces of refrigerant in a 2lb system..yes the compressor will turn when the low side pressure is increased when you add refrfigerant....

 

It says 1lb on the unit but should it still be around 47psi for 95 Blazer. If so I still have one full can and can put it up to 47psi. I put it to 35-38psi as I went by the direction on the kit.

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Like anything else, you need to know how and why AC works before you can diagnose and repair it.

Before the system is turned on, low side pressure and high side pressure are equal. When the compressor is turned on, the high side pressure increases moving refrigerant to the fixed orfice tube. When the refrigerant passes through the fixed orfice tube and into the evaporator, it expands and the low side pressure drops. The refrigerant is sent back to the compressor and the cycle repeats.

There is a clutch cycling switch mounted on the accumulator. When the compressor is running, low side pressure drops. When it reaches approx. 22psi, the switch turns off the compressor. High side pressure drops and low side pressure increases. When low side pressure reaches approx. 42psi, the cycling switch turns the compressor back on, and the cycle repeats.*** This type of system is called a "clutch cycling system". On AC systems other than clutch cycling, there is usually a sight glass to check refrigerant level. Clutch cycling systems offer no way to visually check the refrigerant level. Checking refrigerant level in a clutch cycling system requires the use of two gauges simultaneously. Several things are monitored to determine the level: Ambient temperature, relative humidity, compressor "on" time, compressor "off" time, total cycle time, low side pressure and high side pressure. When the data is gathered, there is a chart to calculate the state of charge. There is only one other way to tell how much refrigerant is in the system: Drain and evacuate the system, and recharge it with the proper amount of refrigerant. If the system is under or over charged, it will not cool properly.

If the system is low on refrigerant, there is a leak that must be located and repaired. The accumulator, (aluminum can), has a desicant material inside that absorbs moisture in the system. The desicant is like a sponge, it will absorb only so much moisture. If the system is empty, the accumulator, (and desicant), is then exposed to the atmosphere. The desicant will absorb humidity and can be saturated in less than one hour! If this happens, the accumulator must be replaced.

After repairing leaks, and replacing the accumulator if necessary, the system must be evacuated. To evacuate the system, a minimum vacuum of 29"Hg is applied for a minimum of one hour to remove moisture in the system. Refrigerant is ALWAYS installed as a gas, not a liquid, into the low side port, (on the accumulator). There should be a label on the evaporator housing that tells how much refrigerant the system holds. Start the engine and hold idle speed around 1500 RPM. Turn AC to MAX position and close all windows. Install the proper amount of refrigerant. In a nutshell, that's AC 101 and hopefully this helps.

*** One characteristic of R134a is that its pressure is almost identical to its temperature. The clutch cycling switch regulates the evaporator pressure between 22psi and 42psi, the average being 32psi. This keeps evaporator surface temperature just above freezing so humidity will not collect and freeze on the evaporator, creating a big block of ice under your dash!