PDA

View Full Version : suction pressure too high while recharging



msgale
10-08-2013, 03:32 AM
System is a Goodman ,1998, 1.5 ton, R-22
There was poor cooling , with pressures low on both low and high sides, and many bubbles in sight glass. I found the leak at the evap, (they always seem to leak there) . I replaced evap. , system then held vacuum, and now I'm in the process of recharging with my dwindling supply of real r-22.
But, halfway through the recharging, the suction pressure is too high, and I wonder if the compressor is on its last legs.
I hate to waste more r-22 to completely fill it , and then discover I need a new compressor. I am not sure how to read these numbers, since I do know the system is still undercharged. Here are numbers while partly charged:

Suc press=102, ( why so high?) evap outlet temp is 66, which calculates to superheat of 8
High side pressure is only 175, with outside air temp of 77, and condenser outlet temp of 87, for a subcool of only 3.
Inside dry bulb=80, wet bub =70
Sight glass shows mostly foam, rarely clear.
Is it worth continuing to charge or can I conclude from the these numbers that I’ll need to replace the compressor ( or maybe replace entire system with new)

passandscore
10-08-2013, 04:26 AM
I would do a pump-down test. If it will not pump-down then you have a faulty discharge valve. If it pumps down but then the suction pressure climbs rapidly then you have a faulty suction valve.


Helpful resource.
http://www.achrnews.com/articles/the-professor-low-head-pressure-high-suction-pressure

msgale
10-08-2013, 04:39 AM
i did a pump down just before i removed the old evap, and suction line went to zero. As i recall, after i turned off the compressor, there was a small rise in suction pressure, maybe a few pounds, then i repumped briefly, and back to zero.i might have done that two or three times and it did stay near or at zero.

moideen
10-08-2013, 06:46 AM
have you done the pump down test after installing new evaporator as passandscore said.just confirm again.

install monkey
10-08-2013, 09:52 AM
should be able to pull 14 inch vac-

i did a pump down just before i removed the old evap, and suction line went to zero. As i recall, after i turned off the compressor, there was a small rise in suction pressure, maybe a few pounds, then i repumped briefly, and back to zero.i might have done that two or three times and it did stay near or at zero.

msgale
10-08-2013, 11:34 AM
have you done the pump down test after installing new evaporator as passandscore said.just confirm again.

no, the pumpdown was done just prior to switching the evaporators.
i do not understand why i should try it again now?

msgale
10-08-2013, 11:37 AM
during the pump down( prior to switching evap's) suction line went to zero,then i stopped pumping, figuring there was no more refrigerant in the system. It might have pulled a vac if I had let it run longer, but i didin't see a need for that.

install monkey
10-08-2013, 11:44 AM
http://youtu.be/gcCcKRX8i7E
:o