Central AC need Freon?

[edcmaak11]

I had this central AC Model#HABA F042SD about 5 years now.  Believed its has 30,000 btu.  I got it checked and put in some freon about 2 years ago.  I am low on buget and measure the temperature out from all the output vents and found the lowest temperature is 61 degree F and other around 65 when outside temperature was 85 degree. 

I just have a new 12,000 btu window sharp AC and blowing 50 degree F.  Is this means I needed to have it put in more freon?  I dont have addtional $200 for the tech to just fill in freon.

thanks!

[RegUS_PatOff]

the temperature at the Duct output will be "higher" because it's losing some temperature to the metal Duct-work.

That may be OK, depending on if the Duct-work is in the insulated part of the house (where that cooling would be OK)]

OR the Duct-work could be insulated...

[edcmaak11]

Thanks RegUS_Patoff! All the metal ducts are insulated.

[applianceman18007260692]

You could get some condenser coil cleaner. I like the gallon size. Apply the cleaner on the condenser according to directions provided. You will be amazed at what this will do.

[applianceman18007260692]

If you can just hose down the condenser real good and oil the motor.

[edcmaak11]

Thanks guys for the replying!

applianceman, I just hosed down the condenser around beginner of June.  I dont think I did a good job because I didnt take out the fan.  Where can I get a bottle of condenser coil cleaner?  How much it runs? 

I would like to take out my fan to oil it, but always afraid bad things happens by chopping my hands off.  My condenser is outside my house while the motor for blowing air is inside the attic.  There is a power switch next to blower, I turned it off before, it also turn off the internet thermostat (from Con Edison==electric supplier). 

One thing I would like to ask you guys.  I was talking to one of a close co-worker about central A/C.  He said that he complained to his brother his central A/C was not cold enough and his brother call his Car Mechanic and filled up with some freon.  Is the car's freon the same as our central A/C?  How do you measure the pressure and how much?  I believe there is a hi and lo valve. 

Thanks again!

[applianceman18007260692]

You cannot use car freon in a home unit.

The coil cleaner can be found at home stores.

The coil cleaner is around $20 for a gallon of concentrated stuff.

You want the acid base for the outside coils the baking soda base for the inside coils.

[edcmaak11]

Do you need a license to buy this freon?  What kind of refrigerant does most central AC used?  I have my AC about 6 to 7 years. 

I really would like to learn how to check and filled by myself.  Really appreciate your help!

[applianceman18007260692]

Looks like that is a 3.5 ton R-22 central unit. It requires R-22 which can only be purchased by certifyable card carrying HVAC dudes. If you had a 30 pound jug of freon connected to your yellow hose and your blue hose connected to the low/suction side, with a clean coil the pressure should be around 68.5 PSI. You could also charge the system by using an ammeter but that is another story. What you oughta do is get with a friend that does that kind of work and get him to show you how to top yours off. Hay every HVAC guy out there had to be taught right?

[edcmaak11]

Thanks for explaining. I will take very slow on learning this.

I checked auto store for the A/C 134a for cars, it said it needs max of 55psi.

I was checking on AC Manifold Gauge. Is there a difference between them? Can I use interchange it with 134a with R22? Will they have residue left behind hurts other system?

After reading the manuals for the AC Manifold Gauges. Why they need 2 pressure gauges(hi/lo)? The low required 60 to 80 PSI and the Hi has to between 225 to 275 PSI. For the low pressure part, if my system is below 68.5 PSI, will I need to filled it to up to 68.5 PSI?

How hard is the epa for the R22 certification? Saw on Amazon that only 1 book dated 2004.

Sorry for so many questions!!!

[applianceman18007260692]

It's not that hard of a test. No questions about repair systems are asked. The test has to do with your knowledge of properly handling freon.

[applianceman18007260692]

The proper charge for automobiles is around 35 PSI. Over 30 I would be listening for fan belt squeal. She starts a squeal you have too much in there.

[colonelh]

First has anyone checked the superheat and subcooling? This is the only true method of proper system charging and capacity verification.

Yes, pressures are a factor as they are temperature related.

If the unit does in fact need refrigerant added it must be of the type that the unit was designed for, ie; R-22, 410A etc.

Also, seeing the age of the system I must ask where did the refrigerant go?

This would be the first step before just "topping off" the system. This is an EPA guidline (your interest in certification prompted me to throw that in) that has regulations about the amount of ref. a system can loose to the atmosphere in a given time.

So assuming that the equipment is in good order and well maintained, you should verify the proper charge and then look at airflow.

Let us know,

COL>