Mitsubishi Mr. Slim MXZ30TN Air Conditioner Logo
j saum Posted on May 14, 2009
Answered by a Fixya Expert

Trustworthy Expert Solutions

At Fixya.com, our trusted experts are meticulously vetted and possess extensive experience in their respective fields. Backed by a community of knowledgeable professionals, our platform ensures that the solutions provided are thoroughly researched and validated.

View Our Top Experts

Pressure in both lines fluctuate from 140psi to below 30psi

System shuts down @ night wont restart , I guess because of  high pressure , so i let out some gas until the system starts , it runs , andthe lines are cold but the air is only cool not cold, @ this point the systemruns @ 70 psi ,  then at night it shuts down and the pressure goes up to 140 again then it won't start again . to make things more complex the system is straight from japan and does not crossrefrence with any U.S. models.  it is a mr. slim style ,  outside compressor is the inverter type , with 2 inside units ,    can anyone help??

  • j saum
    j saum May 22, 2009

    on this unit we only have low side ports to attach the gauges to (no high side ports)  

  • Anonymous May 11, 2010

    Can you tell me what an inverter is? AC-DC??

×

1 Answer

Anonymous

Level 3:

An expert who has achieved level 3 by getting 1000 points

All-Star:

An expert that got 10 achievements.

MVP:

An expert that got 5 achievements.

Guru:

An expert who has written 7 tips or uploaded 3 video tips

  • Master 462 Answers
  • Posted on May 14, 2009
Anonymous
Master
Level 3:

An expert who has achieved level 3 by getting 1000 points

All-Star:

An expert that got 10 achievements.

MVP:

An expert that got 5 achievements.

Guru:

An expert who has written 7 tips or uploaded 3 video tips

Joined: Mar 29, 2008
Answers
462
Questions
1
Helped
252322
Points
1207

The foreign made market is different than the USA.

First if the unit doesn't get a change or input from a manual command (on the remote on mine) it will shut off because it assumes there is no one there.

2nd if it is in the timer mode it may be different in orientation than what you are used to looking at.

TO make sure these are not your problem review the instructions.

If this is R22 or R410A there is not a pressure switch that will cut it "OFF" at 140#. And if your fluctuating tween 30 and 140 It is almost sure its low on charge especially if its new. Now I assume you mean 140 on the high side, right?

  • Anonymous May 23, 2009

    If you have just low side access you now may have the origonal problem plus be low on gas. Never remove or add refrigerant unless your measuring it by weight. This is the only dependable way you have of knowing about where the charge is.



    Look on the copper lines leaving the compressor. If you find a switch firmly ancored or screwed into either line, with 2 wires and you see no clips holding the body down these are most likely the pressure switches. The wires used on most are blue but they could be any color.

  • Anonymous May 26, 2009

    Because your only reading on the low side this fluctuation means even less to me now. Without a high side access it will be more difficult to help you reach a correct and speedy diagnosis.

×

Add Your Answer

×

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1helpful
1answer

At night its shuts down when the therm is satisfied,but trys to restart right away and when it does start it shuts down right away and just keeps doing this

The thermostat has a differential built into the temperature sensing operation. The differential is normally a degree or more. If the stat shuts down at 72 degrees it should not start the unit again until the temperature in the room reaches 73. If the AC runs and cools properly until it shuts down, I would check the thermostat. The AC can not restart immediately after it shuts off because the pressures in the system are too high at the compressor. It takes a few minutes for the pressures equalize allowing the compressor to start. If the stat tells the unit to start under high pressure, the compressor will shut down on overload. It will start and run after the pressure falls enough for the compressor motor to run.
0helpful
1answer

Pressure switch shut-off set too high.

It is adjustable. Remove the square cover nut and adjust the spring tension. . It would be best to lower to 110-115 psi. The compression rings will thank you for it..
0helpful
1answer

1994 chevy cvalier 3.1 engine...lately it's been shutting off when i come to stop. the oil pressure fluctuates and then shuts off. it always starts back up. any suggestions?

if this unit has an over drive tork converter the tork converter or the TC valve (solenoid) might be faulty, have you tried keeping your foot on the gas a bit to keep it running ? and what happens ? also some engines have a low oil pressure warning and engine cut out , did you check your oil ???
0helpful
1answer

MY WL651500AJ IRON FORCE WONT PUMP UP MORE THAN 30PSI IN ABOUT 15 MIN.

First check for leaks: the tank drain valve may not be closed or has something in it causing it to stick open. Check the line from the pump to the tank and the line from the tank check valve to the pressure switch if it has one.
If there are no leaks you have either a damaged piston/cylinder assembly, usually the seal ring on top of the piston or bent or broken reed valves. You just have to remove the head and valve plate to check the condition of the cylinder and valve plate.
0helpful
1answer

My pressure relief valve on my boiler is allowing water to pass through constantly.how do i adjust it to stop the water flow? only have about 15 pounds of pressure in system

Even a small amount of crud on the rubber washer/sealer can cause the valve to seep. Some valves can be taken apart and cleaned but it will be better to replace the valve. They can be found on line for around $12 or more. You will have to shut off the water in take valve and drain most of the system unless you have a main line shut off valve so the system wont drain back into the boiler. These valves are usually set at 30PSI.
0helpful
1answer

Hot water tank does not work when shower is on, it does however work when the faucet in bathroom is on. It quit working in the shower about a month ago.

  1. COLD MIX, HEATER DEACTIVATES
    If inlet water temperature is over 70°F due to geographic location, water maybe very hot out of the tap. This requires a lot of cold water to be added with it in order to attain a useable hot water temperature. The addition of too much cold water will overpower hot water demand from the tankless water heater. This slows the flow within the tankless water heater, decreasing it below activation point, which shuts off the heater. The end result is nothing but cold water coming out of the outlet. See: TWH E2-04 Overcoming fluctuating temperatures [PDF].
  2. FLUCTUATING WATER PRESSURE
    If the water pressure in the home is erratic and the water flow is not consistent while a tap is opened, then the temperature of hot water will fluctuate. The minimum water pressure for the home should be 30psi or greater. For people on well systems the minimum pressure range is 30-50psi. The use of a pressure reducing/regulating valve is an effective way to maintain constant water pressure to the water heater. Watts brand 25AUB- ¾" or N35B-¾" pressure reducing/regulating valves or equivalent is suggested.
  3. CHANGING FLOW RATE
    Major changes in flow rate can adversely affect the output water temperature of the heater. Increases from one major fixture running to multiple fixtures running at one time can cause the temperature to fluctuate. Stay within the heater's specifications. See: TWH E2-03 Outlet temperature vs. flow rate [PDF].
From the Bosch website.

Good Luck,
Gary
2helpful
2answers

Compressor shutting down

FC IS FREON CHARGE, WHAT YOU ARE GETTING IS A HIGH PRESURE CUT OFF  FAILURE. THE LABEL PRESURE IS TEST PRESURE. THE RUN PRESURE ON LOW SIDE IN AC MODE IS ABOUT 65 AT 75 T0 80 DEGREES INSIDE AND ABOUT 200-300 HIGH SIDE AT 75 -85 OUTSIDE TEMP. IN HEAT THE LARGE COPPER LINE BECOMES HIGH SIDE HOT WHEN YOU FEEL IT. IF YOUR FREON IS LOW WILL WILL ALSO GET SHUTDOWN. YOU WILL NEED SET OF FREON GAGES AND CONTACT ME BACK
0helpful
1answer

Air conditioning doesn't keep it cool

Your system may be low on R134a and needs to be recharged, If you did recharge it with the recharge kit and you over charged it, you'll have poor a/c performance too. The low pressure side should have 30psi to 50psi and the high pressure side should have 150psi to 200psi, any other readings will give low a/c performance and if to high of pressure can lead to system damage. Good luck and hope this helps. 
1helpful
1answer

Do you have the specs for the high and low pressure readings for a 2005 Pontiac Montana?

I take it you mean the A/C pressure line. The low side should be between 30PSI to 50PSI and the high side should be between $150PSI to 200PSI. Any other readings will have poor A/C performance, and to high will result in A/C compressor damage. Good luck and hope this helps. Keep me posted be glad to help and if the low side is less then 10 PSI then the system will need to be vacuumed out due to possible moisture contamination.
0helpful
1answer

Pressure switch out of adjustment

Before you adjust the perssure switch, make sure that the intank check valve is not leaking pressure back to the pressure switch after it cuts off at 140psi. The check valve should hold pressure at 140psi. Follow the discharge airline to the tank to find the checkvalve (either chrome or brass with large cap). To check for leaking valve, run compressor till shut-off at 140, then unplug the compressor from wall and remove the 1/4 air fitting at the checkvalve and check for leak. If leaking, replace valve and leave the pressure switch at present setting. You should be good to go. Good Luck with your repair and email if you have questions.
Not finding what you are looking for?

394 views

Ask a Question

Usually answered in minutes!

Top Mitsubishi Heating & Cooling Experts

 Mikey
Mikey

Level 3 Expert

6904 Answers

vince

Level 3 Expert

2530 Answers

Brad Brown

Level 3 Expert

19187 Answers

Are you a Mitsubishi Heating and Cooling Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...