You are here:

Heating, Air Conditioning, Fridge, HVAC/Should these gas valves remain open or closed?


Hello Joe,

My home A/C is a common residential one, it has the blower indoors and the compressor unit outdoors. My questio is about the unit that is outdoors. It has 2 metal (copper?) tubes that go inside the house: one carries cold gas to the inside and the other carries hot gas out, back to the unit. Right where these 2 pipes go inside the metal case of the copressor,each tube has a small cap on the top with an hexagonal shape, like a screw nut. It's like a tiny faucet or valve that you can open and close by turning it to the right to tighten or to the left to open it (get the idea?)

I was doing some garden work around the A/C unit, and I accidentally touched the top of the valve, and noticed it was "lose" I mean, it wasn't completely open nor closed, but in the middle. I donno what those are for, and I don't know if I should tighten it closed or open it completely. How should these be set for normal operation? Thanks in advance.

Best regards,



Those two hexagon caps are for service techs, to hook up their gauge set to check the refrigerant pressures, there is a schrader type ( similar to a car tire access cap, to check air pressure ) those are suppose to be tightly hooked up. ( in case the Schrader leaks ) so yes tighten it snugly.

Heating, Air Conditioning, Fridge, HVAC

All Answers

Answers by Expert:

Ask Experts




40+ years diversified experience.An HVAC/Refrigeration Self Employed Contractor since 1986. NATE Certifield. Answer questions pertaining to Residential and Commercial Air Conditioning , Warm Air Heating, Heat Pump systems.Mechanical and Electrical troubleshooting of these systems.Be as detailed as possible when describing problem.Packaged unit or split systems.No appliance questions.


Installation and Troubleshooting, Mechanical and Electrical, in following areas, Refrigeration ( Walk In and Reach In Coolers and Freezers ) Commercial Roof Top and Packaged Heating/Cooling ( Natural Gas,Propane, Electric, and Heat Pumps ) Computer Room Air Conditoning Systems,Commercial Residential Packaged and Split Systems Air Conditoning and Heat Pumps.Warm Air Oil , Natural and Propane Gas Heating systems.

Graduated from Private Technical School in 1975. An HVAC/Refrigeration Contractor . Have Unlimited Heating/Piping and Cooling Contractor License.Limited Sheetmetal Contractors License.NATE Certifield. York Certifield Master Heat Pump Technician 1986. Served 33 years combination Active Duty Air Force , Air Force Reserves and Air National Guard in the HVAC/Refrigeration Shop/Mechanical Shop. Troubleshooting/Installing HVAC/Refrigeration Equiptment Worldwide. Retiring in 2003 as a Senior NCO ,and a Mechanical Superintendent.

©2017 All rights reserved.