Air Conditioner Freezing Up

[TURTLE]

This is Turtle.

You missed his question on the increase of air through the condenser coil with horse power increase and not RPM.

TURTLE

[TURTLE]

This is Turtle.

Your words sound good but to a 90 year old fellow and a 30+ year old system and he said just doctor it up and when i go I can let some else worry about it.

Now the Uping the horse power and leaving that big ass lennox 24 inch with 45 degree pitch blade on it was really a no no but only for they are going to change the system out soon like in a month or two.

Now the blade causing a extra $100.00 on the light bill a month. Hell here in louisiana in the 1970's we did not know what a $100.00 light bill was or did they go that high.

TURTLE

[RP]

Damn Turtle. Let's try this: The evaporator coil is plugged and the U-bends on the coil are already frosting over, but there is just enough air over the evaporator coil's fins to keep the frost knocked off of them. Then you go out and put a higher RPM motor on the condenser, increasing the condenser airflow. Now the suction pressure is going to drop 3 or 4 pounds from what it was. The coil then begins to frost over because it was right at freezing before you changed the motor. The evaporator was *marginally* close to freezing already, just 32.1 degrees when you got there, or .1 deg above freezing. So it only has to drop .1deg in order to freeze. But 3 or 4 pounds lower suction means that the coil temp has dropped about 3 or 4 deg, so it's now way below freezing.

So you want to add refrigerant to fix it, wrong already, but let's go ahead and add some refrigerant. Now the subcool is way too high, the unit is running less efficiently than before, and because the liquid is cooler (that's what higher subcool means) as it goes into the evaporator the suction pressure will never come back up as high as it was before you changed the motor out. It's now maybe 1 or 2 pounds lower than it was before, and the coil is 1 or 2 degree colder, or still below freezing. Ice still forms even when you add refrigerant, unless of course you overcharge the system, in which case the compressor is going to go out prematurely, because it'll slug liquid when it gets hotter outside.

A system is tuned so that all of its parts work together efficiently and correctly. If you change the balance that was engineered in then you have hacked up the system and aren't saving the customer a single red penny. In fact you probably cost them more in the long run than if you had done it right the first time. If you know what you're doing then you can actually improve upon the original engineering but you don't seem to know enough about the system to even keep it at its original efficiency.

hvacrmedic

[RP]

Turtle, wtf? I'm worried about you, really.

hvacrmedic

[RP]

I said "over the life of the unit". More like I was giving you the benefit of the doubt for them breaking even over 15 years, but in reality their extra expense on electricity would add up to more than 100 dollars over 15 years. A bunch more.

hvacrmedic

[CBHVAC]

Terry forgets that the rest of the country, isnt in the stone ages any longer.

[CBHVAC]

In other words, you raped him. No damn wonder the rest of the techs have a hard time with some people...someone like you was there and took the guys money and didnt do him ANY favors.

You damn liar. IF and I mean IF thats the case, you have a couple of options. Put him in a new system. If and thats IF hes serious, you will have your money in less time than most commercial accounts pay. The other option is to finance him out, and you have your money instantly, and hes gonna pay a few extra dollars in interest, unless you are a legitimate company that can offer 90 days same as cash, and then, hes still going to pay for that new ssytem hes gonna get in a month or two and not pay extra on it.

English wasnt taught there either was it?

[CBHVAC]

Bullshit? First, you are not paying me to teach you. If you want to be taught, AFTER FORTY YEARS in the trade, go back to school.

If you dont understand this simple, BASIC principle of AC operation, there is NO WAY you have ever, in your life, charged a unit correctly, Mr Beer Can Cold Ill pinch em off till its cooling guy.

You also have never worked on an old Trane/GE unit with two speed fans, or knew how that worked either.

[George E. Cawthon]

I agree with most of your statement Slick. But I didn't really ask a question about how it could freeze up, I indicated incredulity at your statement about the "perceived" lower ambient temperature. And, I pointed out that it would really be a problem with the coolant and not the blower.

[Edwin Pawlowski]

Does not matter as long as the hp is sufficient to propel the car at 70 mph. Both cars have the same gearing so the engine turns at the same rpm. I could add a supercharger, put in a big V8, it would still run the same rpm with the same gearing at the same speed. Just like a fan motor.

[Michael.]

When I took the fan motor to the shop they matched it to a motor that was supposed to be the same RPM. I have discarded the old motor, but I will see if I still have the info written down and I will check it to the new one. I replaced with a 3M micro alerigin filter. Cleaning the coils and replacing the filter did not work.

[TURTLE]

This is Turtle.

Your words tell the very most truth but the average customer in this area would do this. I would explain that they could save about $1,000.00 over the life of the furnace if you just add this $6.00 part to it. The Customers having been bullshitted so much that the answer to this question would be " no put the regular part on it". the public has been told so many lies and bullshitted so many time that they don't believe anything a service man says now a days.

If you want a example of the public being bullshitted . go to your TV and turn it on and watch the commercials and see how much bullshit your handed out in advertisements. You are look " up on " as just one of these commercials and playing a game on them.

Also here in Louisiana they are just now getting a $200.00 electric bill and is having sticker shock over it.

TURTLE

[TURTLE]

this is Turtle.

you have listed causes of the problem but what I'm speaking about is ONE STATEMENT THAT CB MADE FOR WHICH WAS NOT TRUE AT ALL. i will slow it down here for you to see it. George up above seen it too but it has slipped by you.

If you have a perfectly tuned & matching hvac system and then you can speed up the condenser fan motor to a point to freeze up the evaperator coil. It will never happen without something else causing the freezing up of the coil.

Now start poking hole in these words and don't start adding anyother statements with it. Just read the statement and speak about it with nothing else or cause added to it.

TURTLE

[TURTLE]

This is Turtle.

they are missing what your saying because of cause of the problem and not what your statement was. i think we are tring to bullshit somebody here but not sure.

TURTLE

[TURTLE]

This is Turtle

George you will never be answered by anybody about your statements above because it is a cover up of someone bullshitting and got cought doing so. CB said it and Richard covering it up. this is the end of it for being caught bullshitting you have to forget about it and move on.

TURTLE

[RP]

There are no locking torque converters on electric motors. They are free to slip, meaning that the rotating field outpaces the rotor. The only way to get the theoretical 1200 RPM, which is the RPM of the rotating field, is to remove all friction and load from the rotor. 1075 is the RPM at which the inherently 1200RPM motor is slowed down by the attached load, which in turn ideally matches the HP rating of the motor. This is why they call it a 1075 RPM motor rather than a 1200RPM motor, though it actually is 1200 RPM under no load conditions.

Adding additional load beyond what it was designed for will reduce the speed still further, but this will overload the motor, causing it to output more HP than it was designed for. At some low RPM caused by excessive drag, the HP curve will begin to drop again and this is called the stall speed for the motor. On multi-tap blower motors the various speed taps are actually just various HP configurations wrt the common lead. IOW, the lowest speed is caused by overloading the motor at the low HP obtained by using the low speed tap. This causes excessive slippage between the field and the rotor and thus we get a lower speed out of the motor. Multi-tap motors are engineered to accommodate the overloaded condition on its lower speeds without burning.

IOW, over-sizing a motor will cause the actual RPM to run higher than the nameplate rating, approaching 1200 RPM as the HP/LOAD ratio approaches infinity. Under-sizing will cause the actual RPM to run lower than the nameplate rating, approaching stall (or zero) speed as the HP/LOAD ratio approaches stall value.

hvacrmedic

[RP]

You aren't going to ever understand.

hvacrmedic

[RP]

When you increase the condenser airflow the system is no longer perfectly tuned or matched. There is no other cause than that you put the wrong f****ng motor on it. The charge is good, by definition of "perfectly tuned and matched". If you add refrigerant to fix it then you've tried to make two wrongs into one right. It'll work, but it won't ever be perfectly tuned again, period, unless you re-engineer the remainder of the system. When you get done with all of that then your wrong motor will now be the right motor, but now it's a completely different system from what you started with. Just put the right f****ng motor on it and shut the hell up.

The OP probably has a dirty evaporator coil and/or low refrigerant charge. Cleaning the condenser coil dropped the suction pressure even lower than its already low value, causing the coil temp to drop and causing the coil to freeze. If it had been 90deg outside the coil wouldn't have frozen, but it was in the low 70's, so it did.

You totally misread what CB said, and I don't care whether you can digest that or not, but I'll stop to say that this sort of behavior is exactly why people got tired of your hack crap posts in alt.hvac. You don't want to learn a f****ng thing, you know very little about your own occupation of 40 years, and while you think you have all the answers you have virtually none at all. I'm sorry, but I didn't raise you, so it isn't my fault. I'm done with trying to educate you, so from now on I'll probably just tell people to run as far as they can from your advice on these groups. If you happen to get one right, then I'll leave that one alone.

hvacrmedic

[Stormin Mormon]

Yes, please call a HVAC company.

[Stretch]

Michael, The 3M filter is one of the restrictive types. Replace it with a cheap fiberglass filter. The pressure drop across the 3M filter is 2.5 times that of the cheap fiberglass filter. Typically it will reduce air flow by 10 to 20%, based on testing with an air flow hood.

If that does not help, you need to call a service company to check your system.

Stretch