Call Us Today!

Milwaukee and Surrounding Areas

Cooling Coil or Evaporator Coil Ice-Up or Frost Over

Cooling Coil Ice-Up on the air conditioner air handler or evaporator coil: Besides a reduced air flow through the HVAC system, a second result of the reduced air flow due to a dirty air conditioning filter can cause the evaporator coil (the cooling coil) in the air handler to become blocked by ice, stopping or significantly reducing cool air output from the system. A visual inspection of the cooling coil in the air handler can quickly show whether or not it’s ice-covered. If the coil is iced-up and blocked, turn off the cooling system entirely until the ice has all evaporated and cleared. Be sure that your condensate drain is not blocked and that the water from melting ice will be properly disposed-of. If you replace all dirty filters on the system and remove ice from an iced coil and the coil ices up again when the system is turned back on, your AC or heat pump system has a frost problem that needs repair.
Cooling CoilCooling Coil
Other Causes Of Icing Up: The air flow is too slow or has completely halted across the cooling coil. The cause of this problem could be as simple as a dirty air filter or it could be crimped, disconnected ductwork or even improperly-sized ductwork. The refrigerant is not being metered properly into the cooling coil, (too little is being released). A clogged capillary tube or a frozen, dirty, stuck thermostatic expansion valve can cause this trouble. Watch out: adding refrigerant to “fix” this problem by raising the compressor head pressure will indeed force more refrigerant through the system. Most icing issues are the result of a leak in the system and the lack of refrigerant will cause the ice build-up on the lineset and inside coil.
Cooling Coil
If you see this on your system, do not continue to operate the unit. You will only do harm to the compressor. Shut the unit down and call your local HVAC contractor. Keep your outside coil clean. If this is what your outdoor coil looks like, then it’s time to give it a bath.
Cleaning CoilCleaning CoilCleaning CoilCleaning Coil
A blown capacitor will also cause a unit to freeze up. The compressor part of the capacitor will run the compressor but the fan part will be blown, thus not releasing the warm inside air from the building, and causes freezing up of the unit. This is what a blown capacitor looks like. You can tell the top of the capacitor is rounded. Sometimes it’s not that easy and you need to use a volt meter to check the microfareds on the capacitor.
Blown CapacitorBlown Capacitor
They come in different sizes and shapes and voltages. Each one specific to each unit.
When it’s warm outside and these units are running continuously for days, this will be the time these unit break down. The main cause is a blown capacitor. Do not attempt to fix yourself. Call your local HVAC contractor and get it repaired the right way. For more articles: visit

About Us

JPR Home Inspections, LLC offers a variety of home and commercial inspection services, including; pre-purchase inspections, new construction inspections, and much more.

Contact Information

JPR Home Inspections, LLC

Serving Greater Milwaukee


  • Waukesha
  • Sheboygan
  • Muskego
  • New Berlin
  • Wauwatosa
  • Lake Geneva