Anyone know about home A/C service?

[pidaster]

I had a 17 year old 2.5 ton Rheem air unit that had leaky valves. When the freon was full it cooled great. Finally replaced it with a 3 ton Goodman unit. The Rheem was around a 8-10 seer unit and the Goodman is 3 times larger. I think I saw something about a 24 or 36 seer on the box when it was installed. Now, here's the question. Now that it's hot outside, it doesn't cool very well. The suction line is extremely cold at the unit and the liquid line is not even warm. Seems to me the old coils in the house (evaporator I think) do not have enough mass to pull enough cold from the lines before it makes it back to the compressor. Does that make sense? It's like it's just pumping it from the high side right back to the low.
Any help or advice would be great so I don't have to sell every gun in my safe to keep my house cool.

[okie shooter]

First thing to see, is the evaperator plugged up, the mass of the evaporator, isnt as critical as good airflow over it, its the expansion and compression of gas that does the work, thus actually the best coils would have almost no mass, just keep the refrigerant apart from the air. Is the fan properly working well, clean and such. Change the filters, and make sure nothing is interfering with the air flow next.

Do you have a little thermometer, try seeing what the air temp is comeing off the evaporator, maybe the expansion valve is plugged or something too. Not sure, I know how to design them if I get the books out but forget lots about how the function and work.

[pidaster]

Filter is clean and fan works great. The coils were dirty but have been cleaned. I can shine a light on one side and see it on the other. I know that's a crappy way to tell but it works for me I guess. I also have no idea where the expansion valve is located. Wouldn't a bad expansion valve cause really high pressure on the liquid line to the point of a release or damage?

[okie shooter]

The expansion valve should be some where near the coil, its kinda of a cup looking thing, with a capilary tube running from it to some where on the coil useally. I am doing this from memory.

Plus you really cannot service it, maybe thump it with a stick if its jammed but no external moving parts there, they are internal.

[pidaster]

Don't see one. I know what one looks like on a car but I don't see one near the coils at all. Could it have been operating without one?

[drine]

Warranty??? Have you not had it long enough to run the AC. Did it work before?

That may be stupid, surely Miss. has been way hot by now.
Not so funny thing is I'm in my basement on my PC next to my Goodman!

I got the owners manual: Troubleshooting,
clean indoor coil and filter.
Clean OUTDOOR coil! You ain't throwed grass in it?
Check return duct. No gun safe sitting on it?
Reclaim, filter, recharge unit...uggh
Remove obstruction to expansion device or change it out.

Hope that helps.

[SSwee]

You will probably need to set some gauges on it to diagnose a little better. Expansion valve restricted will drop the low side and raise the high side. Same basics as automotive AC. Too much or too little Freon will cause reduced cooling. The A coil and the condensor being clean are the first things to check. If you've done that, then gauges to see how the compressor and expansion valve are working. The fan drawing air over the condensor getting weak will cause a reduced cooling. The high side pipe will be hot while the low side will be cold enough to sweat.
SS

[pidaster]

How do I know for sure when the coils are clean? I can shine a light through them so I thought they were now clean.
As for the pressure, with an outside temp of 74 degrees, I had a low side reading of 55 psi (39 in Hg vac) and a high side of 190 psi (97). As of two weeks ago, it had correct pressures according to the a/c guy. I had gone a month without air so it took a while to get the humidity out of the house but it hasn't cooled like it should. The air out of the vent isn't much cooler than what it's taking in.
The fan and heater was replaced at the beginning of last winter.

[okie shooter]

What is the output tempture of the air off the "A" coil. That would tell you if the expansion valve is working right. It should be in the fifty degree area some where, Your low side pressure should be at that pressure/tempture range too.

[SSwee]

The A coil is hard to tell. Light through it means its not plugged but may be dirty unless you can see through it. Try a small mirror.
Is it a R22 unit? I don't do R22 enough to remember the pressures. I have a chart at the shop for R22 pressures at the different ambient temps I can check tomorrow. If I remember correct, you should have a 20 degree difference in air temp between the intake to discharge on a good working unit. I'll hit my brother up on it also. He messes with those more than I and been to school on them.
SS

[pidaster]

Warranty??? Have you not had it long enough to run the AC. Did it work before?

That may be stupid, surely Miss. has been way hot by now.


Oddly enough it just started hitting in the low 90's last week. For the next few days they are saying 97 degrees and I know it's going to struggle pretty bad.
I've only had it for about a month.

I'm going to get some more foaming cleaner and see what it does.
Is the liquid too cold going into the unit causing the pressure to be off so bad?

[RandyCOG3]

I had gone a month without air so it took a while to get the humidity out of the house

Sorry, I can't begin to tell you anything about your problem, but just thought I'd chime in...occasionally at work we'll be called in on a home with a high moisture problem of some sort, and it'll turn out to be TOO MUCH air-conditioner for the home; i.e. a unit that's too big will cool off the air so quickly that not enough air spends enough time going over the coils to adequately condense the humidity out of the total volume of air in the home.
Definately not relevant to your stated problem, but, it's something to be aware of; not sure it should take very long to dry the humidity out of a home. Just food for thought.

RandyCOG3

[AK AJ]

Do you have any lines "frosting up"? your high side reads a little low and your low side reads a little high. Check for frosting along the lines.

[pidaster]

Do you have any lines "frosting up"? your high side reads a little low and your low side reads a little high. Check for frosting along the lines.

No frosting.

[AK AJ]

No frosting.

you sill got the gauges hooked up?

[AK AJ]

if you hook up the gauges get a reading, then switch the unit off , if the gauges both level out imediatally at the same pressure, you have a bad compressor