George B's 2000 Saturn SL2. “The Turtle”

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Got another gremlin to chase.
It got up to 50° today so I tried the AC and found the compressor doesn’t run. All the fuses are good. Looking with the tech2 I can manually command the compressor relay but get a “AC is commanded off” message. I assume this may be an ambient temperature reading issue as manipulation of the AC button doesn’t change the state of the command. I heard that the temperature needs to be above 40° so I should have been good. I will have to look at the data again to see if I can see the ambient temperature input. I don’t have a detailed enough manual to find the sensor itself. I know there is an IAT by the filter but I don’t know if it is shared. The AC relay is controlled by the PCM which also reads the IAT.

May be time for an Alldatadiy sub.

Not sure if this helps; see this link: https://saturnseries.net/s_ects/

Seems to say that the ECTS and IAT are the same sensor, but in different locations.

Edit, here's where he shows the IAT location. https://saturnseries.net/s_iat-sensor-91-02-dohc-95-02-sohc/
 
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George B

George B

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George B

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Recording this here:
High/Low Pressure Cut-Out Switch
A/C off if discharge pressure is greater than 2758 +1/- 138 kPa (400 +1/- 20 psi) and back on at 1724 +1/-345 kPa (250 +1/- 50 psi). Cooling fan will run for 180 seconds after A/C is turned off. A/C off if discharge pressure is less than 276 kPa (40 psi).
Supposed to reach almost 70F today so I will try again.

I need a suggestion on a good gauge set.
 
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George B

George B

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The guys on the saturn forums are freaking useless. There’s at least 10 threads of people asking how to troubleshoot their AC and these a-holes all reply in a condescending manner and never give any good advice. A simple question about normal pressures at both static and 2k RPM results in two pages of nothing.

These guys must be a special breed!
 
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George B

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In the event I need to add some refrigerant can anyone give me any tips and tricks? @randeez maybe? I have read some and watched some videos. I Can handle this even if I need to pull a vacuum on it. I just haven’t ever done this. Figuring it is low and hopeful I don’t have a major leak. I would try to add some dye or get refrigerant with dye.
 

randeez

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In the event I need to add some refrigerant can anyone give me any tips and tricks? @randeez maybe? I have read some and watched some videos. I Can handle this even if I need to pull a vacuum on it. I just haven’t ever done this. Figuring it is low and hopeful I don’t have a major leak. I would try to add some dye or get refrigerant with dye.

does the ac work at all? poor cooling? compressor runs? i use hptuners to force the compressor on, tech2 can prob do it also?
this is the gauge set i use, not sure how/why i chose this particular set but it has worked pretty good, nice hoses, nice manifold... pretty cheap
if it doesnt work at all, i would evac it and pull a vacuum on the system for 30min or so. let it sit a couple hours and see if theres still a vacuum on it.
with a vacuum on the system, it will suck the freon into the system without it even running. when i hook up the little diy cans to the gauge set, i flip the can over and purge the line (theres a schrader valve on the freon hose line) before opening the manifold up to let freon into the system - do this every time you have to change cans. (youll close valves to system off, when you remove can youll introduce air via the hose into the system if not). make sure theres something in the system before starting the car
what I ran into with filling yukon is - the placement of the service ports and readings they give. the yukon has a pressure sensor right after the compressor so i watch that value while filling. the gauges are good for trouble shooting high/low readings - theres a million "guides" just search google. they range from like 25-55psi low side to 155-200psi high side. you can prob look up how much is supposed to be in it by weight and try weighing it out. but i just wing it fill it enough to keep the compressor running, turn ac on full blast and recirc, i use a thermometer in the center vent to watch temp, i'll open manifold to let more freon in the low side (with can upright - gas) for like 10sec at a time, watch thermometer give it a few minutes to drop and stabilize, i do this a handful of times...the first couple youll get 5-6* of temp drop each, when it gets to where youre only gaining a degree of drop or so. thats when i stop. check gauges to make sure pressures are in a safe range.
 
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George B

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Thanks @randeez! Thats what I needed.
The system doesn’t run at all. The pressure switch is open. It’s a combo hi/low switch. I will have to get gauges on this thing next.

If I pull a vacuum and it doesn’t hold I would then fill it as usual but with dye and look for a leak right?
 
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George B

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Static pressure is low. It's about 45F outside and I have 21 PSI in the system. When I disconnected I heard a hiss and noted the Schrader valve is leaking.
 
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