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low pressure side port location on 2005 DeVille


skyman

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Sort of a thread off an old post of mine. Slowly been loosing cold air from my AC. First the two left side AC ducts were not as cold as the pass side then eventually no cold air from the left ducts...only the passenger AC ducts. Weather has been cooler plus made a trip up north so havent used the AC in a while. The other day was quite warm so I turned on the AC and got no cold air from any air duct. One member here said earlier on to just add a can of freon and all will be well. So today I picked up one of the larger cans with hose and pressure gauge attached..Odd but the two ports on the line that runs over the "acummulator?" between the fender and PS pump has both a large and small fitting. The freon kit hose fits the smaller schroder valve fine but I just found it odd that both schroder fittings were on the same line. Do I have the low pressure side? I did test the pressure with the freon kit gauge attached to the smaller fitting with the hose unscrewd from the can of freon and when the commpressor cycled on the needle went all the way up in the red, which I found odd because I don't think I have much freon left in the system or, it's just low.so I ran quick and turned the engine off. ......I remembered when the car was on the lift for my last oil change, the mechanic spotted some oily green liquid to the right "pass side" around the bottom air dam and asked me if I had added any dye to any fluid in the car which I hadn't. Maybe it was a slow freon leak and maybe the factory freon has a dye already in it...... So anyway, is the schroder valve that I hooked onto, the one to add freon to?

Sky

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The only thing that is green that I can think of is coolant, and that should be red, yellow, or orange in your car. But some retrograde technophobes put green in newer cars, even though the owner's manual and other documentation specifically warns against doing that. So, check the radiator surge tank, and if the coolant is green, look for coolant seepage at one of the radiator hose clamps.

Most Freon dye that I have seen is either red or fluorescent under UV lights. But aftermarket dye can be any color.

Have you checked the OBD codes? I believe that 2005 was the last year that you could do that from the dashboard.

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OK

I found some illustrations on Google. The small schroder valve is the low side. It took half the large 18 oz can maybe a lillte more. The passenger side ducts are now ICE cold and the drivers side ducts get cold only at the two lowest fan speeds but still not as cold as the passenger side. So,my guess is that there are two separate air mixing doors and that when the fan is at high speed, the force of the air holds that left door open a bit and lets warmer air into the mix for the left side.

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The ports are on each side of the orifice tube - perfectly normal. The fitting closest to the evaporater will be the low side fitting but the charge hose will only fit on the low side port anyway.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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You can't really tell anything about the state of the charge with the low side only gages. Feel the evaporator inlet and outlet pipes - they should be close to the same temperature. If the outlet pipe is warmer than the inlet pipe, the system is undercharged.

The only accurate method to determine if the system is properly charged is to recover the refrigerant, weigh it and compare the weight to the specification label.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Not being an expert on AC systems, I did panic and shut down the engine when I saw the needle go up into the red on the initial pressure reading. This was without the can of freon attached. Then doing more research I found that you can get this reading if you are very low on freon when the compressor cycles on. Makes no sense to me but to me all my symtoms pointed to low freon. The system took on the freon and during the process, the gauge was always in the bottom green area and never went any higher. Also , I am starting to get colder air on the drivers side even at higher fan speeds now. Frankly I don't understand why but if I had a schematic on the ac system behind the dash that would probably shed some light on the problem. Guess I'm just going to have to order a shop manual.

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The fluorescent green viscous fluid is likely compressor lubricant (PAG) with leak detector. It seems that compressor discharge hose replacement is not an uncommon occurrence on this generation of DeVille, so I'd focus on this area first. Refrigerant leaks on the high side usually result in some lost lubricant, which needs to be replaced to restore system balance.

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