Ac low pressure side is high and high pressure side is low

Information on some common auto air conditioning topics.
Archived Forum

Moderators: bohica2xo, JohnHere, Tim

Post Reply
Posts: 1
Read the full article
Joined: Fri Feb 25, 2022 2:54 pm

Ac low pressure side is high and high pressure side is low

Post by robnav »

Last year the car started to blow the air a little warmer. I went to Walmart picked up one of those cans with the little gauges on it. The gauge said I was low so I filled it up. I had ice cold AC until this month. It started blowing hot again so I said I’ll just recharge it, the problem was when I bought the same can and put it on the gauge said that my system was overcharged. I went online and a lot of people were writing that you need a proper AC manifold gauges.

I got those today, plug them in and according to the paper it came with my system was low on refrigerant. I was about 30 PSI low side and the high side was 200 PSI. The manual said for 83 deg. 40-50 on the low side and 175-200 on the high side.

Started to put the refrigerant out the low side started going down instead of up. So when I saw that I stopped filling it. I was at around 20 PSI on the low side and 210 on the high side. I revved the engine and then the low side went to 90 PSI and the high side came down to 125 PSI.

Any ideas what this could be?

What I have noticed
I went to check if the compressor turns on and I noticed as soon as I turn on the AC it will blow cold air for about 1 minute and then the compressor starts to cycle on and off. It turns on for about 2 seconds and turns off and the car shakes. Then it does the same thing again until I turn off the AC or the car. If the compressor was bad would it still turn on and off? Also, does this sound like it could be a blocked expansion valve?
User avatar
Posts: 955
Joined: Sun May 13, 2018 10:20 am
Location: South Carolina Upstate - USA

Re: Ac low pressure side is high and high pressure side is low

Post by JohnHere »

You won't be able to charge the system correctly using one of those cans with the little gauge on it. Also, you can't charge a system by pressures alone. In short, the charge must be precisely weighed-in using the proper equipment. Additionally, those all-in-one charging cans (known as "death kits" in the trade, and for good reason) often contain sealer, which can and will foul up the entire A/C system. What might have been just a minor leak beforehand, you now could be looking at a total system replacement. Check the can to see whether it contains sealer, and hope that it doesn't.

By the way, what is the make, model and year of the vehicle in question, and what engine does it have?
Member – MACS (Mobile Air Climate Systems Association)

Thankful for the responses you have received? Please consider making a monetary donation to the Forum.
Post Reply