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Got stupid and opened high side valve while charging
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mikemck25
New User
Feb 10, 2020, 10:52 AM
Post #1 of 5
(2601 views)
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Got stupid and opened high side valve while charging
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So this was a total dum-dum move. While charging a recently rebuilt system in an '84 BMW 325i (switching from R12 to R134), we got distracted and mistakenly opened the low AND high side valves on the manifold while charging. We didn't realize our mistake until the first 12oz can of R134a was empty. The low side was spiking around 70psi, while the high side was reading only around 60psi.
We purged the system from the receiver's schrader valve, then pumped it down for 5 hours, let it sit for 24 to ensure there were no leaks, then gave it another shot, but correctly. However, while the low side pressure was within spec for the ambient temp - about 35psi - the high side never got above 75psi, or half where it should have been.
The air from the vent was cool but not cold. When we shut off the compressor, instead of equalizing the low side rose about 15psi and the high side fell about 5 psi.
My gut says we damaged the expansion valve, and I'm hoping we also didn't also hurt the compressor. Before we started ripping the guts out of the system again, I thought I'd ask for thoughts.
It's a Sanden compressor (generic), stock expansion valve, stock evaporator, stock receiver, parallel flow condenser, all new barrier hoses/fittings/o-rings.
(This post was edited by mikemck25 on Feb 10, 2020, 10:52 AM)
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Hammer Time
Ultimate Carjunky
/ Moderator
Feb 10, 2020, 1:10 PM
Post #2 of 5
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Re: Got stupid and opened high side valve while charging
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The only thing you can hurt by doing that is exploding that 12 oz can in your hand, but that's serious enough.
Those pressures sound more like a low charge or there is something wrong with the shrader valves or gauges themselves.
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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.
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mikemck25
New User
Feb 10, 2020, 1:22 PM
Post #3 of 5
(2581 views)
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Re: Got stupid and opened high side valve while charging
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A guy I know who's done multiple retrofits is suggesting I could have installed the condenser upside down. He did that once before and saw similar readings. Now I just have to check...
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Hammer Time
Ultimate Carjunky
/ Moderator
Feb 10, 2020, 1:29 PM
Post #4 of 5
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Re: Got stupid and opened high side valve while charging
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First, I don't know how you could even do that because the fittings are usually different sizes and turning it over would put the fittings on the wrong side of the car so the hoses would never reach.
Don't take any advice from that guy.
It's either low charge or inaccurate gauge readings. Maker sure you removed the protective caps but even that would cause different pressures.
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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.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 10, 2020, 2:20 PM
Post #5 of 5
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Re: Got stupid and opened high side valve while charging
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Quite the circus going on. Anyone paying any attention to oil loss? You can just work from low side if you have enough stuff/equipment. HT already mentioned exploding a can IS THE RISK. That's liquid that wants to be a vapor/gaseous real bad either the impact or instant freeze of skin neither are good news. Just don't allow it and pay attention!
T
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