105 Series aircon freezing (1 Viewer)

[Gregg0]

Hopefully you guys can help with my evaporator freezing up.

I can run it with the fan on 3, but with the fan speed lower it will cut out and then cycle on and off every couple of seconds. While running, the drain absolutely buckets out water.

I've just had it tested again today and all pressures are apparently perfect, my aircon guy is at a loss as to the source of the problem. I dont understand how the evaporator can freeze if the pressures and temperatures are okay. I've put a new thermistor in with no change.

I appreciate your help.

 

[Kamran Khan]

Here is an answer from ChatGPT. Problems like yours are not limited to just a specific make and model of car or AC system.

If your air conditioning (AC) evaporator is freezing up, it typically indicates an issue with the AC system. Here are some common causes and troubleshooting tips:

Causes of an Evaporator Freezing

1. Low Refrigerant Levels
• Insufficient refrigerant can cause the pressure in the system to drop, leading to freezing.
• Solution: Check refrigerant levels and recharge if necessary. A leak might need repair.
2. Restricted Airflow
• Dirty or clogged air filters, a malfunctioning blower motor, or obstructed vents reduce airflow over the evaporator coil, leading to freezing.
• Solution: Clean or replace the air filters and ensure vents and ducts are clear.
3. Thermostat Settings
• Setting the thermostat too low can cause the system to run excessively, allowing freezing to occur.
• Solution: Adjust the thermostat to a moderate cooling level.
4. Faulty Thermostat or Sensor
• A malfunctioning thermostat or temperature sensor might not properly regulate the system.
• Solution: Test and replace the thermostat or sensor if needed.
5. Dirty Evaporator Coils
• Dirt and debris on the evaporator coils can prevent heat exchange, leading to freezing.
• Solution: Clean the evaporator coils carefully.
6. Drainage Issues
• A clogged condensate drain can cause water to build up and freeze around the coils.
• Solution: Clear the drain line to ensure proper water drainage.
7. Blower Motor Problems
• If the blower motor isn’t functioning properly, airflow may be reduced.
• Solution: Test the motor and repair or replace it if necessary.
8. Improper Refrigerant Charge
• Overcharged refrigerant can also lead to freezing.
• Solution: Check the refrigerant charge and adjust it to the manufacturer’s specifications.

 

[Gregg0]

Here is an answer from ChatGPT. Problems like yours are not limited to just a specific make and model of car or AC system.

If your air conditioning (AC) evaporator is freezing up, it typically indicates an issue with the AC system. Here are some common causes and troubleshooting tips:

Causes of an Evaporator Freezing

1. Low Refrigerant Levels
• Insufficient refrigerant can cause the pressure in the system to drop, leading to freezing.
• Solution: Check refrigerant levels and recharge if necessary. A leak might need repair.
2. Restricted Airflow
• Dirty or clogged air filters, a malfunctioning blower motor, or obstructed vents reduce airflow over the evaporator coil, leading to freezing.
• Solution: Clean or replace the air filters and ensure vents and ducts are clear.
3. Thermostat Settings
• Setting the thermostat too low can cause the system to run excessively, allowing freezing to occur.
• Solution: Adjust the thermostat to a moderate cooling level.
4. Faulty Thermostat or Sensor
• A malfunctioning thermostat or temperature sensor might not properly regulate the system.
• Solution: Test and replace the thermostat or sensor if needed.
5. Dirty Evaporator Coils
• Dirt and debris on the evaporator coils can prevent heat exchange, leading to freezing.
• Solution: Clean the evaporator coils carefully.
6. Drainage Issues
• A clogged condensate drain can cause water to build up and freeze around the coils.
• Solution: Clear the drain line to ensure proper water drainage.
7. Blower Motor Problems
• If the blower motor isn’t functioning properly, airflow may be reduced.
• Solution: Test the motor and repair or replace it if necessary.
8. Improper Refrigerant Charge
• Overcharged refrigerant can also lead to freezing.
• Solution: Check the refrigerant charge and adjust it to the manufacturer’s specifications.

Thanks for the reply. Unfortunately, my A/C guy has checked/replaced everything mentioned in your post...and it still freezes.

It's as if the wrong gas has been put in, one that cools too much when under the recommended pressure...this is not the case though, he used R134a gas.

 

[nissanh]

Speeds 1 and 2 are not making a good flow of air. Possibly the amount of air that flows throught the evaporator is low making it to feezeup. Try a good fan and/or the resistor pack

 

[Gregg0]

Speeds 1 and 2 are not making a good flow of air. Possibly the amount of air that flows throught the evaporator is low making it to feezeup. Try a good fan and/or the resistor pack

Thanks for the reply mate. My A/C guy checked the fan speeds and all was good. I've had it running quite a bit today on fan 3, it's cooling well but still bucket-loads of water streaming out of the drain. It will only last a couple of minutes on any lower speed fan before freezing. Once it freezes on a lower speed, it takes a long time before it starts working on fan 3 again, melting the ice and warming up the thermistor I'd imagine.

 

[nissanh]

Its normal to dump bucket full of water from the drain. Guess you are in a very humid area. I think the temp sensor mounted to the ac evaporator is unmounted from the evaporator.

What happens when you set your twmp control to like 25 C?

 

[Gregg0]

I dont have climate control, I'm unable to pre-set a temperature. If I have heater on while AC running, it will still freeze up and cut out. The sensor on the evaporator (thermistor) is doing it's job, as it's cutting out when evaporator gets too cold/freezes.
Thanks again for your help with this.

 

[SNLC]

Pressure sensor/switch shuts off the compressor. It does this to keep it from freezing. This is why an A/C compressor cycles the clutch on and off while the A/C runs. Faulty pressure switch can cause freezing.

I would assume your A/C guy knows this though.

Cheers

 

[SNLC]

I dont have climate control, I'm unable to pre-set a temperature. If I have heater on while AC running, it will still freeze up and cut out. The sensor on the evaporator (thermistor) is doing it's job, as it's cutting out when evaporator gets too cold/freezes.
Thanks again for your help with this.

It’s not doing its job if it is freezing. Perhaps you have the wrong switch. Yes it is shutting off the compressor but not within the correct parameters.

Cheers

 

[Gregg0]

When the AC guy hooks his machine onto it, all the pressures and temperatures are correct, "text book" as he puts it. The compressor will still cycle every couple of seconds, the temperature in the ducts is around 13 deg Celsius, where it should read between 1-4 deg. I've replaced my original thermistor with a new one, but there is no change on operation. The evaporator has been removed , cleaned and checked, and a new TX valve fitted. The condenser is new and pressure switch tested.
I'm wondering if the AC amplifier might be faulty, what's your thoughts on that, apart from being expensive.

 

[Gregg0]

When the AC guy hooks his machine onto it, all the pressures and temperatures are correct, "text book" as he puts it. The compressor will still cycle every couple of seconds, the temperature in the ducts is around 13 deg Celsius, where it should read between 1-4 deg. I've replaced my original thermistor with a new one, but there is no change on operation. The evaporator has been removed , cleaned and checked, and a new TX valve fitted. The condenser is new and pressure switch tested.
I'm wondering if the AC amplifier might be faulty, what's your thoughts on that, apart from being expensive.

SOLVED...Originally, I had replaced my old thermistor with a new OEM thermistor, with no change to performance. All the symptoms still pointed to the thermistor being the cause, but it couldn't be because it was brand new.

So , clutching at straws here, I ended up buying another OEM thermistor (the 3rd to go in) and it works a treat!

How unlucky to get a dud replacement part. Thanks everyone for your input.