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High hi side pressure 400psi

Posted: Sat Jun 21, 2025 1:15 pm
by davemac2
I have a 2009 Nissan rogue that is blowing hot.

I put the gauges on and I'm seeing a high side pressure of 400psi and a low side pressure of 70psi. When the engine is off, I don't see the low and high pressures equalizing either.

I'm pretty sure the compressor is not coming on probably due to the high side excessive pressure. It's a bit hard to see the compressor down on the bottom of the engine but I don't think the clutch is engaging.

The condensor itself looks ok. The driver side fan is on and blowing at full speed as far as I can tell.

I use to do some auto a/c diy work years ago on a few cars, but it's been awhile.

I assume this car is using r134a as far as I know. I don't know whether the a/c system has been serviced before.

I have to assume this is probably a blockage due to a sticky expansion valve or a bad dryer that is clogged or come apart. Is that a reasonable assumption? Next steps would be to evacuate and flush the system, probably replace the dryer, exp valve and maybe condenser at a minimum?

What do you all think?
If I do replace those 3 components, do you recommend attempting to flush the evap core? What do you use for that?

If I find evidence of a disintegrated dryer with dessicant in other parts, is it recommended to replace the compressor also?

Thanks in advance

Re: High hi side pressure 400psi

Posted: Sun Jun 22, 2025 6:46 am
by Cusser
Disclaimer: I'm NOT an AC professional.

1. Did this vehicle have working AC and then it stopped working? Or just not working since you got it?

2. Has a shop pulled out the refrigerant and weighed it to determine if the charge amount is correct?

Re: High hi side pressure 400psi

Posted: Sun Jun 22, 2025 2:28 pm
by davemac2
1. This is my wife's daughter's car. I drove it briefly a month ago and it seemed to be working but very weakly. She doesn't use it too much where she is at the moment because the climate there is typically in the 60's.

2. No we haven't had it at a shop yet so I have no idea about the state of the charge. I don't think anyone has worked on it recently. I'll ask her again though to make sure. I know when I put my gauges on it yesterday, a lot of PAG oil came out of the high side when bleeding off the line. I know my gauges are accurate because I used them just after to measure the pressures off another working vehicle and they were as expected around 24/190psi.

Re: High hi side pressure 400psi

Posted: Mon Jun 23, 2025 9:16 am
by JohnHere
Have the refrigerant recovered, and then remove the liquid line at the TXV. If you find desiccant beads, then the R/D has disintegrated.

Re: High hi side pressure 400psi

Posted: Thu Jun 26, 2025 4:15 am
by JohnHere
If, say, the ambient temperature is 65°F, then the low side and high side should read about 30/160 PSI respectively.