There are 12 potential causes for an Air Conditioner to Freeze Up. Most of the time the it comes down to low refrigerant or bad air flow across the evaporative coil. Low refrigerant is a quick fix for most technicians. For this reason we find that it is over diagnosed. In my experience low refrigerant only accounts for about 25 to 30% of the cases. Because it is the quickest and easiest to solve, it will be the go to diagnoses for inexperienced or lazy HVAC technicians. Here is why.
It takes about 15 seconds to figure out that the system pressures are out of wack. Even if it is bad air flow adding more refrigerant can solve the icing up problem. The trouble with this is there is rarely do they dig deep enough to find the leak.
You Should never need to add refrigerant
Your AC system is a closed system. If it is 40 years old it should still have the original refrigerant it was born with. If not you need to ask why. Some leaks are pretty obvious. Others are slow and more difficult to find. At the very minimum the person that ads refrigerant to your HVAC should tell you where the leak is and repair that leak before she or he adds refrigerant. Spoiler alert. Shrader cores are the most likely culprit.
Bad air flow is a more likely candidate for your AC icing over
If I had to put a number on it I would say 3 out of 5 service calls we go on where the Air Conditioner to Freeze Up, at least one of the problems is a clogged air filter. A $2 fix that the customer could have fixed themselves. Unfortunately, a dirty air filter typically means that the evaporative coil is also dirty. Cleaning a coil is difficult on 90% of all AC systems. It is a job for a pro. Aside from being able to access the coil, which can take some effort, it has to be put back together and then resealed.
Most of the time a new filter, cleaning the coil and or adding refrigerant can solve your AC icing up problem. If all of these check out to be okay here is a list of the other potential issues a smart HVAC tech might find.
1. Condenser is too large for the coil
2. Clog in the liquid line dryer
3. Partial restriction at the metering devise
4. Bad TXV
5. Kink in the refrigerant lines
6. Blower motor not turning or not tuning ad proper speed
7. Damaged coils
8. Air filter too thick
9. Collapsed duct work
10. Too many air vents closed
Most people will only notice they have freezing up problem when it is very humid and very hot. If that is where you are at, change the filter and see if that solves the problem. If not shut the unit off and call your favorite AC Repair Company in Las Vegas. Running a system that is iced up will damage your compressor. This can turn a $220 problem in to a $2500 problem. Fast Affordable Air will diagnose the real problem(s) and give you an affordable solution.