Usually either the system is low on coolant or the return air filter needs to be changed. Filters are relatively cheap so change them every 30 days.
You could be having an issue with the TXV valve also
Stuck compressor contact relay. Metering device or refrigerant restriction. Plugged service drier. Collapsed duct or ducts too small. Dirty indoor coil. Damaged coil fins. Dirty air filter. Failed or intermittent indoor fan motor. Failed fan capacitor. Bad blower wheel. Bad blower belt. Failed fan relay. Broken or shorted low volt wiring. Failed thermostat. Improper wiring. Low ambient inside or outside temperature. Wrong metering device. Thermostat set too low. Low refrigerant. Mismatched inside coil and outside condensing unit. Dirty air filter.
WHY IS MY AIR CONDITIONER FREEZING UP:
THERE ARE MANY REASONS WHY YOU’RE AC (AIR CONDITIONER) FREEZES UP. IT DOESN’T MATTER IF IT IS AC UNIT OR CENTRAL AIR CONDITIONER, THE MOST COMMON CAUSE OF YOU’RE AC FREEZING IS FROM DIRTY AIR FILTER. AC UNITS REQUIRE PROPER AIR FLOW AND DIRTY AIR FILTERS IMPEDE AIRFLOW.
IF YOU SEE ANY ICE FORMING ON THE PIPES THAT LEAD FROM THE COMPRESSOR OR OUTDOOR UNIT, BE SURE TO CHECK YOUR AIR FILTER.
ANOTHER COMMON CAUSE CAN BE LOW ON FREON (GAS), THEN YOUR AC CAN FREEZE UP DUE TO LOW PRESSURE INSIDE THE SYSTEM. THIS IS BECAUSE OF LOW FREON. AS YOUR AC EVAPORATOR COIL DROPS BELOW FREEZING, THE MOISTER IN THE AIR WILL FREEZE AS IT COMES IN CONTACT WITH YOUR COIL CAUSING IT TO FREEZE OR ICE UP.
AC ARE DESIGNED TO FUNCTION IN A SPECIFIC TEMPERATURE RANGE. IF YOU ARE RUNNING YOUR AC AND THE TEMPERATURE OUTSIDE IS BLOW 62 DEGREES THE PRESSURE INSIDE YOUR SYSTEM WILL DROP AND THIS WILL CAUSE YOUR AC TO FREEZE UP.
WHEN YOUR AC IS WORKING TO MANY HOURS UNDER VERY LOW TEMPERATURE ON YOUR A/C CAN ALSO CAUSE THE A/C TO FREEZE.
LETS NOT FORGET THE MECHANICAL FAILURES CAN ALSO CAUSE YOUR AC TO FREEZE UP. IF THERE IS A BLOWER THAT ISN’T RUNNING OR IS DINGED AND OUT OF BALANCE, IF THERE IS KINK IN YOUR REFRIGERANT LINES, OR A CLOGGED FILTER DRYER, THEN THIS TOO WILL CHANGE THE PRESSURES IN YOUR SYSTEM AND IT CAN MAKE YOUR AC FREEZE UP.
BLOCKED OR CLOSED VENTS WILL BLOCK AIR FLOW TO THE EVAPORATOR COIL. CAUSING THIS TOO TO FREEZE UP YOUR AC.
ONE OF THE BEST WAYS TO PREVENT AC UNITS FROM FREEZING UP IS TO MAINTAINE YOUR AC UNIT WITH SERVICE TUNE-UP,TECHNICIANS THAT WILL PERFORM THE NECESSARY TASKS TO PREVENT FROM FREEZING.
Great question. The most common reasons I’ve found frozen ac systems here in Texas are 1) dirty air filter 2) low on refrigerant (will usually freeze at night/early morning) 3) dirty indoor coil.
These are not the only reasons they freeze up but I would say top 3.
Most of the time it’s due to a dirty component such as the filter(s), the evaporator coil, secondary heat exchanger, the blower wheel, or all of the above.
But there are so many more mechanical and refrigerant issues that a qualified and experienced technician should check before assigning the problem to a simple dirty filter. I would imagine it’s very frustrating when a technician charges $100 to change a filter and then the AC freezes up again later that day. But if the technician spends time and checks the entire system, that $100 filter change is well worth it.
Sometimes a new Merv 8 or Merv 11 air filter is too restrictive. Most contractors do not design around the high restrictive pleated air filters causing some systems to freeze up. The A/C coil condensates moisture in the summer, so fine particles will get stuck in the condensation and will be drained off. By using a restrictive filter for allergies you might be causing such a restriction that you’re actually pulling in dust from leaks in your ducting system causing more of a allergy problem than you had to begin with.
Short answer is generally either a refrigerant leak or air flow restriction.