# high head pressure low suction



## whitelaker

I have a 3 ton system, 410a, running at 90 psi low side and 310 high side. When I arrived on site the indoor coil was frozen as well as the suction line on the line set. Checked the indoor coil (clean), air filter is new and I washed the outdoor condenser. The space temp was 83. I was thinking that the tx valve might be the problem...any thoughts


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## cascadehvac

looks like an air flow problem. are there vents closed? is the fan runnibg properly? if you leave off blower door does it run better?


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## whitelaker

I never thought to try that, I was too focused on a faulty tx valve when I go back I`ll give that a try, I`ll let you know


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## JohnH1

I would rather know the super heat and sub cooling along with inside temp and outside temp.


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## josephsiaq

FYI, if you techs carry a smart phone, windows phone or iPhone there is a great ac app called HVAC buddy. Plug in ALL of the info and out comes a diagnoses. Really helpful.


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## beenthere

JohnH1 said:


> I would rather know the super heat and sub cooling along with inside temp and outside temp.


Yep, pressures don't tell enough of what is happening to make a good diagnostic call.


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## Vaporx

"high head, low suction"

310 isn't high, unless the outdoor temp is 70F which probably isn't the case. Typical condensing temps for 13 SEER cooling equipment is 15-20 degrees above outdoor temp. The saturated temp for 310psi is right at 99F. So, if the OD was much above 85F, the head pressure was on the low side.:001_unsure:

Superheat and subcooling measurements would tell you whether the problem is low air, low charge or TXV / LL restriction.:yes:


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