Educate Me Section
Educate Me/Home
James A/C Co./Home
Diagnosis of problems
Understanding refrigeration
Homeowner helpful hints
Filtration & More
Understanding thermostats
Outside units and safety
Indoor Coils and drains
Links & Search
Air Purification Products
Honeywell® Thermostats
Humidifiers
Unit Heaters
HVACR TOOLS
Accessories
James A/C Co.
serving Do-It-Yourselfers since 1990.
Satisfying every customer....one at a time!
|
|
Call toll free 1-866-584-0355 or 1-903-759-2160 fax 903-759-4605
309 Patriot Circle, Longview, TX 75604-2240
THINGS TO CHECK IF THE INDOOR AIR FLOW IS INSUFFICIENT:
- Refrigerant undercharge causes icing of the cooling coil and a low head pressure and
air can't flow through ice. Likely the coils indoors will allow some movement of air even when iced, but very little. Many things
can mask as an undercharge, so check the subcooling of the condenser and the superheat of the evaporator coils. For example, if the
condenser coils are wet, the pressure of the entire system will be reduced. Low refrigerant charge will result in very low
subcooling or none at all.
If the undercharge has a reduced head pressure, the pressure in the cooling coil will be low. Remember that the temperature and
the pressure work directly together with refrigerants. Normally, the temperature of the cooling coil will be above freezing by
the design of the manufacturer. This keeps the moisture that will form on the fins and tubes from freezing. As a system
looses refrigerant it will become closer to the freezing point and will eventually decline low enough in pressure for the
corresponding temperature to become below 32 degrees F. and the moisture from the air will freeze on the tubes and fins.
- Dirty evaporator coils will surely restrict the air flow and must be eliminated as the
cause. If the coils are dirty, then the service technician will have to remove them, clean and treat them. You will likely not
be able or will wish to tackle this big of a job. Cleaning them in place will create a huge mess and will not adequately clean
the trapped matter from deep inside the fins. No need to even try this approach. Besides, you will likely as not do damage to
the fins if you try to surface clean them.
- Dirty filters are another prime cause of freezing. If a filter becomes very dirty,
it will reduce the airflow through the system and the cooling coils will ice some of the time or even every time it is running.
Many of the so-called permanent filters are restrictive anyway and when they become dirty will quickly make the airflow too low
to keep the cooling coils from freezing. Look for any restriction of the airflow through the system as the cause of low airflow.
Reduced airflow can be from many reasons:
- Loose belts will slip and the speed of the blower wheel will be reduced. Belts
will crack and stretch and need replacement. Watch for very grooved belts and worn pulleys. For small air conditioning
applications adjust the belts to this tension:
- Very dirty blower fins cannot move air properly.
- Even check to see that no paper or plastic has sucked up into the blower or on the
filter face.
- Don't let objects stored under the unit in the return air restrict the air flow.
- Look for loose insulation inside the blower section or in the ducts or plenum.
- Look for crushed ductsin the supply air system and in the returning air system if
there is one.
- Make sure that all the supply grills are open to the proper amount. Most of these
grills will have dampers or louvers up inside them for air volume and/or direction control. They will not necessarily need to be
wide open, but you check to see that enough openings of the accumulative amount from all of the grills is sufficient for allowing
adequate air flow if everything else is okay.
- Some systems will have air flow control dampers in the ducts and this will need to
be checked to determine if they are set open enough for the total system to deliver enough air flow if all else is okay.
- The thermostat setting may have been set too low and at some point the indoors
temperature may have gotten too cold for the system operation and the coils may have frozen. The indoor air should never
become less than 68 degrees F. unless special controls have been added to the system.
- Extremely dirty condenser coils will cause a reduction in the condensation of liquid
in the refrigerant and the result is gassy bubbles going through the cooling coil restrictor instead of a full flow of liquid.
The result is less refrigerant flowing into the evaporator coil and thus the pressure is low and the coils will ice. Many
people overlook this cause of low pressure in the cooling coil, so watch for it.
- Restrictions of the refrigerant flow to the cooling coil will reduce the pressure in the
coils and result in freezing.
 |
Look for clogged filter/driers and kinked refrigerant lines. Remember that a restricted tube will have a cooler area downstream
of the problem area. Repair the kink or replace clogged filter/driers. Sometimes, evaporator coils as well as condensers will have
a strainer inline with the liquid flow. Watch for a restriction at that point, too. |
|
|
Honeywell®
VisionPro® IAQ
whole house control
Honeywell®
FocusPro
non-programmable
in2 Energy ICM®
Connects Thermostat to Computer and Internet.
Honeywell®
Electronic Air Cleaner
Honeywell®
Media Filters
Honeywell®
UV Lights & Bulbs
Honeywell®
Carbon Monoxide
Alarms
Honeywell®
Electronic Air Cleaner
Replacement Cells
Honeywell®
LineVoltPRO™
programmable
Honeywell
Rectangular Zone Dampers
Honeywell
Round Zone Dampers
Reznor
Infrared Heaters
|
