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Ac high an low side readings

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Old Mar 5, 2025 | 08:08 AM
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Default Ac high an low side readings

After reading some other threads I bought manifold gauges. My low side is higher than my high side. Not quite sure what to look at next now that I have this information.

The reading are while the car was running. It was maybe 80 degrees outside, I live in FL.



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Old Mar 5, 2025 | 08:16 AM
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Those are both about the same, 75 psi, which is pretty close to ambient temperature. It would appear that either your compressor is dead, or more likely not running, even if the control says it is. A properly charged system at rest for several hours will read just like this. Time to visually check on whether the compressor's clutch is engaging and spinning the compressor.
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Old Mar 5, 2025 | 09:20 AM
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What is your issue that you needed to buy a manifold set ??….when the car is off the pressure should be about the outside temperature…don’t think your compressor is operating.
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Old Mar 5, 2025 | 09:45 AM
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Originally Posted by redzg
Those are both about the same, 75 psi, which is pretty close to ambient temperature. It would appear that either your compressor is dead, or more likely not running, even if the control says it is. A properly charged system at rest for several hours will read just like this. Time to visually check on whether the compressor's clutch is engaging and spinning the compressor.
so when I had an autozone freon with gauge it was not spinning until I added freon. The autozone gauge said 27-29psi so I kept adding and it would budge. So after reading comments I bought the manifold gauge and these are the readings.

The clutch is engaged when I turn on the AC. Another thing to not is my climate control screen does not display, I still need to fix it. I set it to auto and twist both driver and passenger to the cool side and then the ac light comes on and that is when i test it.
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Old Mar 5, 2025 | 09:53 AM
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If you have to add Freon you have a leak…my advise is to take it to an AC Shop and let them diagnose it…AC is not a DIY repair because other than the manifold set you don’t possess the equipment necessary to do this kind of work…you have to be accurate to the ounce when adding refrigerant.
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Old Mar 5, 2025 | 11:31 AM
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Originally Posted by Juanm1024
so when I had an autozone freon with gauge it was not spinning until I added freon. The autozone gauge said 27-29psi so I kept adding and it would budge. So after reading comments I bought the manifold gauge and these are the readings.

The clutch is engaged when I turn on the AC. Another thing to not is my climate control screen does not display, I still need to fix it. I set it to auto and twist both driver and passenger to the cool side and then the ac light comes on and that is when i test it.
You have no clue what you are doing. Take the car to an AC repair shop before you damage the vehicle's HVAC system or cause injury to yourself.
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Old Mar 5, 2025 | 07:33 PM
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Sure looks like a nice gage set for a first stab at this. Might I ask who sells them?
By all means the best option is to hit your local "Ice Cold Air" or equivalent shop. The problem I read here is the far too common unreadable controller. I would anticipate any A/C shop less than familiar with the C5 to want that fixed first.
If you want to continue self edification, the controller should just be possible to read at night. Which, alas, is one of the worst possible times to see if the compressor is running.
Repeat your baseline gage measurement with the system static, i.e. engine and A/C off for several hours. You should see pretty much exactly what you have in the photo, both high side and low side with pressure approximately equivalent to ambient temperature. If the static pressure is even between high and low sides, but lower than ambient temperature, you can add refrigerant via the low pressure (blue) port. At 75 psi it can be difficult to get the system to take more refrigerant from the can, even a fresh can. Setting the can valve side up in a small bucket of warm water will increase can pressure and make transfer easier. Warm water, not too hot. The can isn't designed for 212°F.
Start the car. Press the 'OFF' button on the HVAC control. Verify no A/C light and, if you can, verify the clutch on the compressor is not engaged. Press the 'Auto' button and watch the 'A/C' light. Does it illuminate and stay illuminated, or does it flash one of more times and go out? If it flashes, how many times?
If the A/C light illuminates and stays illuminated, check your gages. The low pressure gage should go down and the high pressure should go up. Regardless, check whether the compressor clutch is engaged and the compressor spinning. If the A/C light illuminates and stays illuminated, but the gages don't show a significant change in high and low pressures, then there is a problem in getting the compressor to spin. It could be a broken wire or corroded connector to the compressor. Time to fix that controller so that you can have Ice Cold Air (or local equivalent) take a look.

Last edited by redzg; Mar 6, 2025 at 08:40 PM. Reason: Kind of illegible, some errors fixed, hopefully no new errors
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Old Mar 5, 2025 | 07:47 PM
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Originally Posted by redzg
Sure looks like a nice gage set for a first stab at this. Might I ask who sells them?
By all means the best option is to hit your local "Ice Cold Air" or equivalent shop. The problem I read here is the far too common unreadable controller. I would anticipate any A/C shop less than familiar with the C5 to want that fixed first.
If you want to continue self edification, the controller should just be possible to read at night. Which, alas, is one of the worst possible times to see if the compressor is running.
Repeat you baseline gage measurement with the system static, i.e. engine and A/C off for several hours. You should see pretty much exactly what you have in the photo, both high side and low side with pressure approximately equivalent to ambient temperature. If the static pressure is even between high and low sides, but lower than ambient temperature, you can add refrigerant via the low pressure (blue) port. At 75 psi it can be difficult to get the system to take more refrigerant from the can, even a fresh can. Setting the can valve side up in a small bucket of warm water will increase can pressure and make transfer easier. Warm water, not too hot. The can isn't designed for 212°F.
Start the car. Press the 'OFF' button on the HVAC control. Verify no A/C light and, if you can, verify the clutch on the compressor is not engaged. Press the 'Auto' button and watch the 'A/C' light. Does it illuminate and stay illuminated, or does it flash one of more times and go out? If it flashes, how many times?
If the A/C light illuminates and stays illuminated, check you gages. The low pressure gage should go down and the high pressure go up. Regardless, check whether the compressor clutch is engaged and the compressor spinning. If the A/C light illuminates and stays illuminated, but the gages don't show a significant change in high and low pressures, then there is a problem in getting the compressor to spin. It could be a broken wire or corroded connector to the compressor. Time to fix that controller so that you can have Ice Cold Air (or local equivalent) take a look.
thanks, going to checkout out what was mentioned. Got the gauges from Amazon.
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