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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 8768
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Medallion a.c. unit blowing pipes frosting : It blows but is

Customer Question

Medallion a.c. unit blowing pipes frosting
JA: I'll do all I can to help. Tell me a bit more about what's going on so we can help you best.
Customer: It blows but is not cooling and the pipes are covered in frost
JA: Is there anything else the HVAC Technician should be aware of?
Customer: It's a medallion a.c. unit
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the HVAC Technician about your situation and then connect you two.
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.

Hello, if the pipes are frosting and *the indoor blower is running*... then the cooling coil is iced over,

there are many causes.

Let me know if that is the case or not, we can go from there.

Customer: replied 1 year ago.
Expert:  Phil replied 1 year ago.

Hello again, the causes of coil icing are as follows, in order of most common to least common"

1. Dirty air filter, and/or cooling coil... the older the system is the more likely the cooling coil is dirty...dirt blocks the air flow

and allows the coil to run below 32F (freezing point of water).

2. Running the system in cooling mode with the thermostat set below 70F when it is cooler than 72F outside, that allows the cooling

to run below freezing (reason is quite technical)

3. System is slightly low on refrigerant, that allows the part of the cooling to ice, then with no air flow across the iced section, the

rest of the coil ices.

Expert:  Phil replied 1 year ago.


Turn off the cooling mode and set the fan in 'fan ON' mode so that the fan runs, but not the outside AC unit

Wait 4 hours or so and the ice will have all melted.

Unplug the furnace or air handler so that the blower shuts down, reach into the blower wheel after it stops spinning and feel for any dirt built up on the blower vanes... if there is a build up of dirt there, the cooling coil will be clogged with dirt also.

The cooling coil needs to be cleaned, that is a messy job.. takes a layman 3 hours or so, or you can have it done for $250 or so.

Look for the dirt, let me know what you find.

Expert:  Phil replied 1 year ago.

Please rate my answer positively, that way the company pays me for my time. Rating does not affect your charges, but is how I earn a living.

In exchange I will hold the question open for coaching on how to clean the coil and investigation of other potential causes without a time limit or any additional charge.

Thanks! I am off to bed now however, I will pick your response up first thing in the morning.