AC question

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PlayingWithTBI

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Just a followup -

Got all of the new parts installed after flushing the evaporator and hoses. Then evacuated the system for 2 hours. Put 4oz PAG46 oil in the compressor and 4oz in the receiver.

New parallel flow condenser
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New AC Delco compressor. When I disconnect the high pressure switch (white wires) I wired in series with the low side, it shuts off just like I knew what I was doing, lol.
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Let it run for about 10 minutes at idle to let the oil disperse in the system then, took it out for a drive - nice cold air. Even heard the fresh air door cycle ~30 seconds after starting it up with fan on high. Now, let's see how long this one lasts!
 

Ken K

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Sweet! The only difference that I can see with her truck and yours is the location low pressure switch. Hers is mounted on the receiver dryer itself. It's interesting, and sometimes frustrating, that GM made so many minor tweaks even in the same model year. It's certainly a learning curve. Thank you very much.

The oriface tube system is called "Clutch Cycling Oriface Tube" or "CCOT". The pressure switch on the accumulator is dual purpose as when suction pressure drops too low, it shuts the system off. As pressure increases, it turns the systems back on. The pressures are different from R12 and change when using R134a. I hope they sold you the correct low pressure switch to work with you upgrade.
 

PlayingWithTBI

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The pressures are different from R12 and change when using R134a. I hope they sold you the correct low pressure switch to work with you upgrade.
Some of them are adjustable using the screw between the electrical blades. Most of the OE were, aftermarkets are set and super-glued in place.
 

KO1960

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The oriface tube system is called "Clutch Cycling Oriface Tube" or "CCOT". The pressure switch on the accumulator is dual purpose as when suction pressure drops too low, it shuts the system off. As pressure increases, it turns the systems back on. The pressures are different from R12 and change when using R134a. I hope they sold you the correct low pressure switch to work with you upgrade.

Thanks. I did order the low pressure switch that is for the R134a conversion.
 

KO1960

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The saga continues. We purchased the switches and wired them according to TBI’s instructions. With the parallel flow condenser, the only place that the orifice tube would fit is between the compressor and the condenser. We vacuumed down the system and checked for leaks, all good. Then we began to charge the system, and it didn’t take long for the low side pressure to spike to 140 psi.

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I believe that the orifice tube is in the wrong position and should be on the liquid line between the condenser and the evaporator. The only solution that we could think of is to cut in an inline orifice tube on the liquid line; although, there seems to be different kits. Any thoughts? Thanks.
 

PlayingWithTBI

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The orifice tube needs to go between the condenser and the receiver/drier. Did you hook up the condenser lines wrong?

The compressor pumps the liquid through the condenser 1st, the condenser cools the liquid, then the cooler liquid goes through the expansion valve (orifice tube) which turns it into a cold gas, that gas goes through the receiver/drier and then the evaporator which cools the cabin, then the warmer gas goes back to the compressor which compresses it into a liquid starting the cycle all over again.
 

PlayingWithTBI

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Mine is in the line between the condenser and the receiver/drier next to the fender well. Mine's an 88, newer models had a different condenser and the orifice tube went in the line next to the condenser. Those condensers had a little different positioning of the lines coming out.
 
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KO1960

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Yes. The old condenser had the orifice tube coming out of the bottom of the condenser to the evaporator. The new parallel condenser that came with the kit doesn't have room for the orifice tube. On our truck, the receiver drier is between the evaporator and the compressor.
 
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