Help

[dogdidit]

I have a problem with the pressure on a unit.
Suction 45-50 lbs
Liquid line 210
super heat 15
sub cool 20
return air 72
supply air 54
good amount of air flow.
Can not get suction pressure up. I can't seem to figure out the problem(if i even do have one) Anybody have any ideas

[markj]

Type of unit, brand, model #, refrigerant might be helpful. Also maybe operating conditions.

[jayguy]

it appears that all is operating ok...even if i dont know exactly what you have. assuming txv and dx cooling coil, you are not getting the heat out of the coil and into the refrigerant...dirty coil on the air side or dirty tubes on the refrigerant side (like from an old burn out or something).

a little more info would really help...i really hate assuming.

[crab master]

What is your outdoor temperature? You subcool seems a bit high but if you have a low OAT then your subcool will be a bit high. I also really don't see anything wrong especially with the low high side pressure.

[tex~n~oz]

sounds like a dirty evaporator (indoor) on a heat-pump.

[crab master]

sounds like a dirty evaporator (indoor) on a heat-pump.

Granted we need more info. but why? A TD on the indoor coil of 18 deg and a superheat of 15 deg sounds great to me.

[jayguy]

Granted we need more info. but why? A TD on the indoor coil of 18 deg and a superheat of 15 deg sounds great to me.

while the td's sound ok, it takes an evaporator saturation temp of 22F to 26F to get 54F leaving air. an evaporator saturation pressure of about 68 psig, gives you about 40F saturation temp, which would be closer to normal. it could be the very beginning of a leak/loss of charge but the high subcooling gives it away. probably not a leak. since there is very little heat transfer, the txv does not let much refrigerant into the low side. the refrigerant has to go somewhere, so it sits in the condensor and gives up all of it's heat so you get a lot of subcooling.

[tex~n~oz]

Jayguy...

I like the way you think. Spot on.