How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Phil Your Own Question
Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 5648
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
23932409
Type Your HVAC Question Here...
Phil is online now
A new question is answered every 9 seconds

Just installed 2 new goodman 3.5 ton systems. On startup the

Customer Question

Just installed 2 new goodman 3.5 ton systems. On startup the suction pressure will only go down to 150 on r-410a unit. Or the unit is defiantly low on refrigerant. New coil and condensing unit, also new furnace.
What is I going on. Did I miss something.
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.

Hello

So far it sounds like the systems are over charged with refrigerant.

To assess that for you I need to know each detail of the following things:

1. Outside air temperature, and pressure read from the smallest diameter tube on the outside

condensing unit.

2. Suction pressure, and at the same exact instant, the temperature inside the house.

We can go from there.

Expert:  Phil replied 1 year ago.

I also need to know if you used a vacuum pump during the installation or not.

Customer: replied 1 year ago.
we triple evacuate.
Suction side pressure 155 return air temp 83
discharge side pressure 325 outside air temp 94These are from yesterday
Customer: replied 1 year ago.
Also these pressures are at start up from yesterday. We have had no other pressures on the system.
There is a site glass but it is bubbles and only
Customer: replied 1 year ago.
Ok but can you still talk by text
Customer: replied 1 year ago.
Are you still there Phil.?
Customer: replied 1 year ago.
Hello Phil
Customer: replied 1 year ago.
Don't leave me now Phil. Thanks
Expert:  Phil replied 1 year ago.

Hello again,

Sorry I am late, my internet provider was down for 3 hours.

Tell me if there is a Thermostatic Expansion Valve (TXV) fit to the evaporator coil or not, if not, tell me the orifice size you fit and what orifice size the spare that Goodmans sends is.

It is possible that you need to fit a smaller piston orifice (those spares come with Goodman equipment). but hold off on that for now. Since I have no idea if you are a 20 year experienced technician or new to the business I need to make sure that you are not bypassing head pressure to the suction side through your gauges.

Do you have both the left and right side gauge valves closed (rotated clockwise)? I need to know if you are using electronic gauges or not, and if so, which brand.

Beyond that, for a 3.5 ton system the orifice size at the cooling coil needs to be.

Here is a video that will give you some insights on the issue.

https://www.youtube.com/watch?v=CbbQC6aQSWI

We can go from there.

Related HVAC Questions