high head pressure low suction

 
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Old 05-11-2011, 09:19 PM   #1
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high head pressure low suction


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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Old 05-13-2011, 11:57 AM   #2
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Re: high head pressure low suction


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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Old 05-14-2011, 08:47 AM   #3
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Re: high head pressure low suction


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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Old 05-17-2011, 08:12 PM   #4
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Re: high head pressure low suction


I would rather know the super heat and sub cooling along with inside temp and outside temp.
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Old 06-04-2011, 05:25 PM   #5
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Re: high head pressure low suction


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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Old 07-03-2011, 06:38 AM   #6
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Re: high head pressure low suction


Quote:
Originally Posted by JohnH1 View Post
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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Old 07-04-2011, 08:16 AM   #7
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Re: high head pressure low suction


"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.

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