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Weird AC issue

Good Evening all from Sunny South Florida,

I have a 2012 Kia Rio5 EX with about 108k miles. I have noticed that when the AC is on low between 1&2 the pressure behind the air starts to decrease, if I turn it to 3 or 4 it makes noise as if the system is clogged. I come from a line of residential AC mechanics, the first thing I checked was the High and low sides, and the system is fully charged. I do not see any ice on the lines going to the condensor. but I do have a substansial amount of water dripping from the car in the garage once it’s parked. I am thinking it’s freezing somewhere but Im not exactly sure where to check. I have replaced the cabin filter, and the air cleaner for good measure with nominal improvements. It’s worth noting it has occured once while utilizing heat instead of cooling,. I am hoping someone can take the time to help me diagnose the problem. I do not have a warranty on this car, and would like to attempt to fix it on my own. I am willing to pay for anyone’s time to help me with this issue via any digital payment method

P.S. The AC never gets warm unless i utilize heat.

My that the evaporator is freezing over when the fan is on the lower speeds.

But it also occurs when the heater is on. I was told the fan speed resistor can be failing

It could be. Why not just use speeds 3or4 when the a/c is on?

To be honest, I rarely have the AC on 3/4 high enough to notice since the AC blow cold. I haven’t noticed it happening at those speeds. A resistor in my research affect the fan on 1/2/3 but will work on 4. which isn’t my issue. it’s really intermittent. if the AC was freezing how would i see it? i never see ice on any parts

I thought it was the air door actuator, but i can see the door opening and closing when i toggle the ac on and off.

One clue to a frozen evaporator is a lot of water dripping out the condensate drain 10-15 minutes after the car is shut off.

I have a good amount of water under the car during hot days. if i was to changethe evaporator, would I have to discharge the system?

You don’t change the evaporator for that. Causes of a freeze up are:
Low refrigerant charge
Inadequate air flow ( clogged cabin filter. Clogged air inlet grill, bad blower motor)
Operating a/c when the ambient air temp is too low.

First step is to make sure the radiator fans are working correctly, turning on when they should & spinning as fast as they should be etc. Next is to verify the AC condensate is able to flow through the AC drain hole without any obstructions. That hole clogging up is a pretty common complaint here, not just on your car but cars in general. It may need to be blown out by a shop using compressed air. To rule out the blower fan inside the car, see if the problem goes away if the blower fan is kept on high.

When checking the high/low pressures, was the engine RPM’s at about 2,000 with a large fan blowing at the condenser?

Mobile AC isn’t like stationary AC.


Yes it was

Blower motor works as far as I know, it runs variable speeds with the dial. Cabin filter is brand new refrigerant is checked and correct it doesn’t appear to happen when temp is low, but I’d have to confirm

Where does it drain? When it drains water does seem to drip. I haven’t noticed water inside the cabin. The fans spin fast when the ac is clicked on

If you were to crawl underneath the car and look at the underside of floor in the area of the evaporator you’d probably see some sort of tube.

Evaporator is inside the car, correct?

It is, and a short hose runs from the evaporator case through the firewall to dump the water outside. You mention the refrigerant levels are ok. What are the high and low side pressured with the engine at 1500 rpm and the fan on 1, and then with the fan on 3.

Yes, inside, It looks a little like a small radiator located up under the dash. It’s the part the AC system that gets really cold, then air is blown through it by a fan who’s speed you control by the dash controls, which then cools the air inside the car.

The other part of the AC system that also looks like a radiator is called the “condenser”. That part is located in the engine compartment, near the engine’s coolant radiator. In order to cool the evaporator the laws of physics dictates that something else has to get hot, and that something else is the condenser.

So exactly what were the high and low side pressures at elevated RPMs?

I’m going to have to recheck, but based on my research and ambient temperature it was correct