Evaporator popping and clicking noise when coolant starts

Problems related to residential installations.

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Evaporator popping and clicking noise when coolant starts

Post by jc113883 » Tue Nov 15, 2011 5:05 am

Hi All,

I have an unusual noise from my split system air con indoor unit.

Let's say I have the unit in cooling mode, but it has reached thermostat temperature and so the coolant has stopped pumping from the outside unit (I'm assuming this is how it works). When the coolant pump kicks back in again, a noise starts up after about 1-3 minutes of operation. The noise is coming from the evaporator coil in the internal unit. I can replicate the noise by running my fingernail along the cooling coil when the unit is offline. It is a metallic pinging noise, with the same frequency (occurance rate, not sound frequency) as if you ran your thumb over the teeth of a hair comb. It lasts for up to a minute and then stops.

The problem is that it is just loud enough to wake us up at night and results in bad sleep from an otherwise good air conditioner.

Does anyone have any ideas?


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- Evaporator popping and clicking noise when coolant start

Post by juster » Tue Nov 15, 2011 8:17 am

I assume this noise just started as it was not bothering you previous to this.
If this is the case then you should call a mechanic to investigate. I would schedule the visit when you know that conditions are such that you will need cooling. The mechanic will be able to simulate by raising the set point on your thermostat but it it warm enough to actually require cooling, conditions will be more realistic and the mechanic will be able to trouble shoot the problem. Keep track of when this condition happens before the mechanic shows up, inform him of what conditions are happening and when. Write it down. This will help.

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- Evaporator popping and clicking noise when coolant start

Post by Freon » Tue Nov 15, 2011 2:34 pm

Next time you can simulate this noise, go to the indoor air handler and CAREFULLY place your hand around the WARM smaller copper tubing entering the evaporator coil. If you feel pulses in the tubing when you also hear the noise, it's probably bubbles in the R-22 flowing through the tubing and into the orifice. If the tubing has no feel of vibration then see if you can locate where the noise is coming from.

If you feel pulses in the tubing you may be able to stop that by having a tech come and determine if your system is correctly charged.

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