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Refrigeration gauge set © D Friedman at InspectApedia.com Refrigeration Gas Test Gauge Q&A-2
FAQs on using refrigerant gauges

  • POST a QUESTION or COMMENT about how to hook up and use an air conditioner, heat pump, or other refrigeration equipment refrigerant gas pressure test gauge

Air conditioner & heat pump refrigerant test gauge FAQs set #2.

This article series describes the connections, use, and reading of a refrigerant gas pressure test gauge set.

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Refrigeration Charging / Testing Gauge Q&A-2

R-22 refrigerant and air conditioning test gauges (C) Daniel Friedman

Recent questions & answers about refrigerant test gauge use, connections, charging ports, posted originally at GAUGE, REFRIGERATION PRESSURE TEST - be sure to review the procedures and advice given there.

On 2018-07-20 by (mod) - how does refrigerant flow through an A/C or heat pump?

Yes anon.

In simplest terms, starting at the "high side"

  1. refrigerant leaves the compressor outlet as a high temperature, high pressure gas,
  2. is condensed to liquid refrigerant,
  3. is metered through a metering device or TEV
  4. into an evaporator or cooling coil, where it
  5. expands into a gas,
  6. and that state change cools the coil (expansion from liquid to gas absorbs energy and thus heat),
  7. the coil then cools air blowing across the coil, and
  8. that lower-pressure gas moves on to the "low side" of the system where it
  9. returns to the compressor suction side inlet.
  10. where the compressor compresses the refrigerant to a high pressure gas

On 2018-07-20 by Ralph Mcdonald

When checking automotive AC system does the high pressure side flow through into the low pressure side as a cycle?

On 2017-11-17 by Tony

My low pressure service port is 1/2", all the manifolds I can find are 1/4" and I do not seem to be able to find around adaptors or hoses with 1/2" connector at the end. What am I missing?
Thanks!

On 2017-11-17 by (mod) - how to hook up a test gauge set

Zeleke,

The procedure for connecting a test gauge set to a refrigeration system is described in the article GAUGE, REFRIGERATION PRESSURE TEST

You'd follow that procedure and then record high side and low side pressures when the system is running as well as after it has been shut down long enough for the system pressure to be equalised.

However only air conditioners, heat pumps, and most commercial refrigeration systems are factory-equipped with gauge ports. A residential appliance like a refrigerator or freezer usually does not have those ports installed.

Those connectors can be added on a residential appliance and are often done-so during repair or during a compressor replacement.

To make sense of the pressure readings that you obtain you need to know

- the specific refrigerant in the system, such as R22 or R410A

- the ambient temperature

- the gauge readings

On 2017-11-17 by Zeleke Ayalew

How can i test the exact value of the recharged gas in the Refrfrigrators system by manufold gage
Thank you
Zeleke Ayalew from Ethiopia

On 2017-11-16 by Reyaz.

Red guage in gas charging equipment gives

On 2017-11-10 by Tony

Hi there. Thank you for this extensive guide, I am studying it. I am a DIY'er and I totally appreciate that I shouldn't attempt to connect a split AC unit on my own but I want to give it a go anyway. I totally understand the risks involved but I think I can make it!
I

am sourcing a vacuum pump, pipes and flanging tools. Once everything is there and connected I will need to create a vacuum in the line, open the gas taps on the unit and hope that the engineer who decommissioned the unit left the gas in the condenser unit!

I only have one question so far. The test gauge manifold has High and Low gauges.

My outdoor unit has two taps and ONE service port on the LOW pressure side. Where is the High pressure service port? Do I need it? In the end I do not have any gas (R410a) so I will only hope that gas is already inside and check the pressure when the unit is running but I am a little confused by that.

The unit is a 7Kw Fujitsu, outdoor unit is AOYR24LCL. I do appreciate your help on this! :)
Cheers!

On 2017-07-05 by (mod) -

Not quite. Refrigerant in the can is a liquid. Depending on the equupment used by the tech, a system can be charged by adding gas to the low side or liquid to the high side of the system.

On 2017-07-04 by Anonymous

You said" do not send liquid refrigerant into the low side of a refrigeration system

But i read at another website that you charge the system: If you add refrigerant, you add it to the low pressure line as a gas

I thought we always charge from the low side (blue line) and i thought all refrigerant comes in gas and not liquid form

thank you

On 2017-06-12 by (mod) - is it technically possible to add refrigerant without a gauge set

Ruben

If you are asking if it is technically possible to add refrigerant without a gauge set, yes of course, though adding an unknown quantity, especially to a system in unknown condition could damage the equipment.

Consider that we don't find and fix a refrigerant leak in a building air conditioning or heat pump system we are basically continuing to dump refrigerant into the atmosphere - illegal, harmful to the environment, and wasteful. There are "stop leak" products that can be added - with mixed reviews and mixed success - or not success, as those too might clog a refrigerant metering control component and thus damage the system.

On 2017-06-12 22:15:54.896970 by Ruben

I know I have a leak can I put in r410a feron in unit with out checking gauges

On 2017-05-15 22:02:47.019203 by (mod) -

Thanks for asking that Anon as many people may get fooled by a technician who's not good at explaining why she chose to just add refrigerant to an air conditioner or heat pump system.

1. Refrigerant does not get "consumed" in an air conditioning or heat pump system. The refrigerant is circulating in a gas or liquid form (changing state between those) in a sealed system. The key word is "sealed".

2. If refrigerant is "lost" from an air conditioning or heat pump system then there is a leak.

3. leaks are not "standard", not "normal" and certainly not desirable: leaks of refrigerant contaminate the environment, cause the equipment ultimately to stop working, and overall increase heating or cooling costs.

4. the best solution when refrigerant has leaked out of a system is to find and fix the leak, then re-charge the system with the proper refrigerant quantity.

5. However some HVAC techs find that the cost of taking the time and trouble to find a leak can be so costly compared with just adding refrigerant that if an air conditioner or heat pump refrigerant leak is so small that the system will work for a year or two between charges their customer prefers to keep doing that. In my view it's not a very nice solution, and this approach, in the hands of a less scrupulous air conditioning repair company can change their business into something like a milk route: just drive around and deliver refrigerant to our customers on a regular basis.

On 2017-05-15 21:03:31.647930 by Anonymous

Goes added gas mean that there is a leak or does gas get used up

On 2017-04-21 23:30:11.583859 by (mod) -

David,

The PRESSURE in any R134 system depends in part on ambient temperature as well as what the compressor is producing.

For example, an R134 system at 90 degF (32 degC) will show

Low side pressure 44-55 psi / 310-379 kPa
High side pressure 250-270 psi /1724 - 1862 kPa

Stop by your local refrigeration supplier and pick up an R134 pressure/temperature chart

On 2017-04-18 16:33:53.101833 by David

What pressure is required for the R134a refrigerant on a 2005 Toyota Matrix XR? The clutch start every 10 seconds and stop in 2 or 3 seconds. I change the compressor and the pressure is 45 psi.

On 2017-04-07 20:23:41.523418 by (mod) -

John,

to have space and to cite authoritative sources (compressor motor manufacturers) I have moved our discussion and links to some PDFs into the bottom of the article above - though it may take a few hours for the updated page to appear online.

On 2017-04-07 05:43:58.160911 by John

Thanks, I check somewhere else and it tells me that the port I was talking about is a process port. There is the suction and discharge line, but this particular one says it's a process port. What worries me is the uncertainty of this process port. if it is on the low or high side of the compressor.

On 2017-04-07 by (mod) re: using the process port on an HVACR compressor motor

John,

to have space and to cite authoritative sources (compressor motor manufacturers) I have moved our discussion and links to some PDFs into the bottom of the article

at GAUGE, REFRIGERATION PRESSURE TEST - though it may take a few hours for the updated page to appear online.

On 2017-04-07 05:43:58.160911 by John

Thanks danjoefriedman, I check somewhere else and it tells me that the port I was talking about is a process port. There is the suction and discharge line, but this particular one says it's a process port. What worries me is the uncertainty of this process port. if it is on the low or high side of the compressor.

On 2016-12-30 22:35:38.924965 by (mod) re: bad heating element on a frost-free refrigerator

Alvis

Your suggestion sounds perfectly reasonable, though the idea turns out to be more of a challenge than one might imagine.

A/C and heat pump equipment does not consume refrigerant. The system is hermetically sealed and the same refrigerant should stay in the equipment for its lifetime, barring mechanical damage that causes a leak. So we're not looking for something like a fuel tank gauge that's found on a car.

Your comment on frost-free equipment is spot on.

Heaters keep frost-prone surfaces such around a freezer door or on the freezer internal surfaces either warm enough to not form frost/ice OR a timer periodically runs a de-frost cycle. In the latter case on older refrigerators you'll find a drain into a pan below the refrigerator/freezer.

The pan catches the meltwater and lets it slowly evaporate into the environment.

If you disconnect just one heater element, say for a door, the unit may still have its internal defrost cycle working.

On 2016-12-30 21:47:10.741357 by ALVIS JENKINS

Actually I have a question. I have been told that a frost free refrigerator is frost free because of a heating element used to melt ice on the evaporator in the freezer compartment. 'Well, my frost free refrigerator is still frost free because my heating element went bad and I disconnected it. If you know how a frost free refrigerator works, please enlighten me. Thanks.

On 2016-12-30 21:42:00.942996 by ALVIS JENKINS

Wouldn't it be nice if AC Heat Pumps exhibited a readout of the unit when it runs low of gas so that owner can get adequate service before complete failure?

On 2016-08-16 21:37:44.294439 by (mod)

Thanks NJ Snowman, I've edited your remark and an appropriate warning into two places in the article above. - Mod

On 2016-08-16 20:32:10.904856 by njSnowman

In the section Guide to Refrigeration Gas Test Gauge Use you show a hand drawn schematic of the test gauge set.

According to what I see if both valves (the silver knobs) are opened simultaneously the Low Side and High Side will be connected directly together. In other words all three connecting hoses are connected together via the test gauge manifold.

I think a clear warning should be spelled out against opening both valves at the same time.

On 2015-12-14 09:41:04.116077 by suraj

Y refrigerator both tune gets ice

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