HELP AC line freezes when the AC turns off...

hondaspeder

Ok so when the AC is on everything is cold and working fine. When the AC turns off the line freezes or gets a light frost on it... if you turn the AC on the frost goes away and everything is working fine?

My question is when the AC is off should the line frost up like that? What would cause this?

Filter is brand new...

All help is appreciated.

biggles

if the line is showing some frost when the system satisfies,it is just the balance of the liquid refrigerant equalizing into the air handler evap,and with no fan runnig it acts like a refrigerator.

hondaspeder

So this is normal?

GetYourShineBox

there could be a few things causing this.

any idea if your evaporator is frosting at all? ( any sign of water in the hander)

is your return filter dirty? how about the blower motor assembly? evaporator could be dirty as well.

your metering device could possibly be feeding too much refrigerant too fast causing refrigerant to enter the suction line.

or the system could be underchanged(low ambient temperature when the system was charged possibly).

just a few ideas.

hondaspeder

The handler (or thing in my addic) has frozen over a few times and this leads to water in the drain bin below the unit.

The filter in the house looks good.

Not sure where any other filters are?

When you say the evaporator could be dirty, do you mean inside the evaporator or outside the evaporator?

The weird thing is the AC works fine.. blows cold and has been since we moved in 3 years ago...

What do you think it would cost to have someone come take a look?

GetYourShineBox

not sure how much a service call costs around where you are at. call around to some places.

sktn77a

Depending on where you are, $100 if nothing major. If repairs/parts/refrigerant needed then anything on up from there.

biggles

if the unit is OFF and the sun swings on the condenser the freon within could heat up along with the liquid line "raw copper" in the direct sun....just like a garden hose directly in the sun!this heating of the line could actually cause a refrigeration effect at the air handler with the higher pressure liquid equalizing into the evap.if the evap isn't covered with ice then its no big deal.if your running R-22 as a freon the running pressures are 65/260 on a blazing hot day when the unit cycles off on the stat.the liquid freon continues into the air handler with the refrigeration cycle until it equalizes...and small amounts of ice might be seen if your right there,and if your in FAN/ON position the ice will never show...with the air moving over the coil,but if your in AUTO/FAN it might.first thing the tech is going to grab is the freon can to add more gas $$$$.run the unit and have the tech up at the air handler where you saw the ice on cycle off of the stat and have the FAN in AUTO so the ice a comeith

hondaspeder

So I realized that when the AC kicks off inside the fan and compressor outside continue to run as they run frost/ice starts to form. The longer the AC is off the more frost/ice forms. (the fan stays on the entire time)

If I manually force the fan and compressor off by flipping the breaker box in the garage the frost/ice will melt.

So whatever is supposed to turn the fan/compressor off is not working..

What would that be?

sktn77a

Have you recently re-wired or changhed the thermostat? Could be a short ion the wiring (eg nail, sharp corner cutting the insulation).

hondaspeder

I have not...

sktn77a

Bad thermostat?

hondaspeder

I changed the thermostat no luck... anyone have a wiring schematic for a home AC system?

hondaspeder

Also its important to note that the compressor continues to run even with the thermostat completely disconnected... (just the four wires hanging)

sktn77a

So the outside condenser runs whenever it's connected to power? Sounds like a short in the thermostat wiring. What happens if you disconnect the connections from the thermostat/air handler at the condenser?