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Old 06-14-2010, 09:25 PM   #1
Join Date: Jun 2010
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Pee poor delta t

Checked out a unit today
92 degrees outside temp
90 psi lo 400 hi
3 ton
I fixed a kinked suction line, and recovered some freon
Inside temp 83, 72 psi lo, 325 hi
about a 9 degree temp diff.
sub cooling 11
super heat 29
coil was only cold 1/2 way up
I am being told that it sounds like a pluged coil
Coil adp 3 ton wity 73 piston
Outside unit gmc 3-ton purrs like kitty cat
liquid line very hoy and I saw no filter dryers.
Any ideas?



Last edited by mikethe ductman; 06-16-2010 at 10:31 PM. Reason: liquid line not vapor line is very hot
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Old 06-14-2010, 09:42 PM   #2
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Superheat is WAY too high so it sounds like the coil is only being partially fed. There may be a strainer inside the fitting B4 the orifice. May be inserted into the elbow/Lennox does that. I had a chunk of silfoss floating in a system and periodically plug an orifice. Sounds like your orifice is partially plugged with wax/debris or the strainer in front of it. Here is an old school chart for superheat, RH matters too:
13 SEER or higher you need the manufacturers chart.


"Cut it twice and it is still too short".

Last edited by yuri; 06-14-2010 at 09:53 PM.
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Old 06-15-2010, 06:49 AM   #3
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You have more then a restriction problem. I won't say you even have a restriction.

Look at your high side saturated pressure/temp. R22 at 325 PSIG, is a sat temp of 137F. Its 92 outside and you only have 11F of SC? That means your line temp is 126F. So your not cooling the refrigerant enough.

That is not an indication of a restriction. It indicates a dirty coil, or a condenser fan problem. Lots of Goodman condenser coils look clean. But are actually very dirty. Many of them are split coils. And the dirt is in between the 2 coils where you can't see it. And a normal garden hose wash/rinse won't clean it out.

You need to remove the top of the condenser. And spit the coils apart(CAREFULLY). And then clean them.

Its possible to clean them without splitting them. If you use a good pressure washer. And a good strength chemical cleaner. usually takes 2 or 3 washes to get it clean enough.

You might even find that its slightly low on charge, after the coil is cleaned.

PS: I have seen this on a lot of Goodmans. Specially at apartment complexes(not to bust on maintanance guys).
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Old 06-29-2010, 06:17 PM   #4
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You nailed it beenthere.

The coil looked clean but the old saying "Looks can be deceiving" rang true.

I got some Ace foam and clean coil cleaner and washed out the coil.

Pressures were 73 & 235, delta t at coil 19.

The people are saying its doing great.

BTW you were right, it was low on freon too.


Last edited by mikethe ductman; 06-29-2010 at 08:24 PM.
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