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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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The suction line gauge is almost at 250psi and the liquid

Customer Question

The suction line gauge is almost at 250psi and the liquid line is at 175psi and it's 99F outside. The ac is blowing warm air. Any idea what the problem is.
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.

Hello, it sounds like you might have the blue hose on the blue gauge attached to the smaller liquid line service valve, and the red hose attached to the red gauge attached to the larger line and service valve.

Beyond that, it sounds like the system *might be over charged with refrigerant.

Tell me as much as you can in detail about what has been done to the system lately.

We can go from there.

Expert:  Phil replied 1 year ago.

Also please tell me if both hand wheels on the gauges are turned clockwise (closed) when you took these readings.

Customer: replied 1 year ago.
The system was recharged about 4 months ago because it was low on freon (the coil kept freezing up) and the coil was cleaned also. Worked fine until yesterday, air from the vents was gradually getting warmer. The blue hose is connected to the larger pipe and both wheels are shut tight.
Expert:  Phil replied 1 year ago.

Hello again, The compressor could be going bad, but even in that event the physics of how these systems operate does not support those pressure readings. I will opt out so that other of our experts here can see your question.

Good luck with it.

Expert:  BillyHvac replied 1 year ago.


My name is Billy.

Is the suction cold and the other line warm?

It sounds like a heat pump that has lost the reverse valve and is in heat mode instead of cool

Customer: replied 1 year ago.
Used a Fluke infrared thermometer and both lines are at 95F.
Expert:  BillyHvac replied 1 year ago.

Thank you

Can you put a magnet on the reverse valve?

Is reverse valve getting 24v?

With a nonactive reverse valve the unit will only heat.

Customer: replied 1 year ago.
Doesn't have a reverse valve
Expert:  BillyHvac replied 1 year ago.

if not a heat pump....and you say suction pressure is higher than head pressure..

If this is true you either have gages on wrong or the gages are bad.

This is like saying the air coming from an air compressor is 175 psi....yet going into the tire is higher.

You have things hooked wrong or bad tools. The suction cannot be high than the liquid line. It is physically impossible.