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Refrigerant pressure diagnosis

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New User

Sep 5, 2021, 2:11 PM

Post #1 of 3 (783 views)
Refrigerant pressure diagnosis Sign In

Hi, working on a 2007 Honda Civic LX 1.8 sedan, auto, 43K miles. AC not cooling. Static pressure is like 125 PSI (it's hot out). When the clutch engages, the compressor sounds fine, no nasty noises. The low side drops to 110-115 PSI, and the high side drops to like 120 PSI. Anything I should consider / try before declaring the expansion valve toast? Thanks!

Hammer Time
Ultimate Carjunky / Moderator
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Sep 5, 2021, 3:20 PM

Post #2 of 3 (780 views)
Re: Refrigerant pressure diagnosis Sign In

Yep, a new compressor. Unless you forgot to close your gauge valves, your compressor is doing nothing.

I don't know where you got expansion valve from.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

Tom Greenleaf
Ultimate Carjunky / Moderator
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Sep 5, 2021, 7:20 PM

Post #3 of 3 (767 views)
Re: Refrigerant pressure diagnosis Sign In

This car and many others hold so little refrigerant just hooking up to see it loses too much! If you are sure compressor is engaging your gauges are just not open/closed properly Hammer Time's first thought.

Before you go tossing compressor which is doing nothing try to vacuum and recharge this to exact listed amount listed under hood or should be. I see 18oz is nothing, which means if you lost 2-3 ounces it wouldn't work but would still show static pressure like you saw just means there's some in there. Pretty much you just witnessed that temps around items holding refrigerant was about 100F.

Hard to touch these low volume systems without starting over with a known weight best when done with ambient air temps of about 85F as measured coming through the grill and known compressor engaged.
Higher end equipment does this by itself is unaffordable for the DIY market and folks, hate to say it BUT MOST FOLKS SHOULDN'T TOUCH anything to do with refrigerant. Risk of letting some out or adding too much and wreck the whole show is too risky.

Sorry for the book on this but just find a shop that does this, say what happened let them properly charge it then and only then are you going to get a clear diagnosis it's messed up already to guess,


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