Air Con Freezing Up

[wandrinstar]

Easy to test for leaks just put Wasing Up Liquid on the Joint. Early Big M Nissans had the Air fitted here, Always going wrong. I had the first single Cab around here, a Lifetime ago it seems.

[GamLing]

All this technical stuff is very interesting indeed but.............

I had the same problem with a new Mitsubishi G-Wagon on it's second outing; the day after I bought it. Travelling through Khorat, the cold air flow into the car was minimal and the four steaming bodies, including mine, were sweating like pigs. I stopped at the Mitsubishi dealer and the maintenance department took one look, stopped the engine and, within a few seconds, there was a water deluge from the exchanger drain. I had set the temperature control to the coldest and the recirculating air, loaded with moisture from the car occupants breathing, iced up the system and blocked the air flow. The recommendation was to set the control at 50%. Never had the problem again.

Have you noticed the pools of water at traffic lights? This "problem" is commonplace and the short stop at traffic lights defrosts the system and the water drains to the road.

[WarpSpeed]

^ Thats the correct way to diagnose the ac system def.

Unfortunately thermometers and freon/R134a sniffers are a novelty here..

[WarpSpeed]

All this technical stuff is very interesting indeed but.............

I had the same problem with a new Mitsubishi G-Wagon on it's second outing; the day after I bought it. Travelling through Khorat, the cold air flow into the car was minimal and the four steaming bodies, including mine, were sweating like pigs. I stopped at the Mitsubishi dealer and the maintenance department took one look, stopped the engine and, within a few seconds, there was a water deluge from the exchanger drain. I had set the temperature control to the coldest and the recirculating air, loaded with moisture from the car occupants breathing, iced up the system and blocked the air flow. The recommendation was to set the control at 50%. Never had the problem again.

Have you noticed the pools of water at traffic lights? This "problem" is commonplace and the short stop at traffic lights defrosts the system and the water drains to the road.

It's called condensation from the evaporator and yes it is a normal part of proper operation. But in the case you described, though, it was solved with their recommended solution it was a symptom and not the actual problem, you just went around it but you should not have to use outside air to thaw it, it should work fine in all modes of operation without freezing..

Edited June 5, 2011 by WarpSpeed

[GamLing]

It's called condensation from the evaporator and yes it is a normal part of proper operation. But in the case you described, though, it was solved with their recommended solution it was a symptom and not the actual problem, you just went around it but you should not have to use outside air to thaw it, it should work fine in all modes of operation without freezing.

Yes, of course it was a symptom. The car did not have the option of using outside air; there air was re-circulatory only and, depending on the sustained humidity within the car and the excessive demands placed upon the evaporator, these systems do ice up and restrict the re-circulatory air flow through the evaporator. This was the cause. The residual heat from the engine thawed the system and the drain.

Edited June 8, 2011 by GamLing

[transam]

It's called condensation from the evaporator and yes it is a normal part of proper operation. But in the case you described, though, it was solved with their recommended solution it was a symptom and not the actual problem, you just went around it but you should not have to use outside air to thaw it, it should work fine in all modes of operation without freezing.

Yes, of course it was a symptom. The car did not have the option of using outside air; there air was re-circulatory only and, depending on the sustained humidity within the car and the excessive demands placed upon the evaporator, these systems do ice up and restrict the re-circulatory air flow through the evaporator. This was the cause. The residual heat from the engine thawed the system and the drain.

Why does does the ride not have the use of outside air? Bordering on dangerous to use only in cab air.

[Gary A]

You experts think about this a bit. The inside air is already dehumidified. The outside air contains much more humidity.

The clutch? If the evaporator is freezing, the clutch must be working quite well. If the evaporator is freezing, that means everything is working too well. Obviously the system is delivering to much refrigerant to the evaporator.

Use the thermometer in the air duct.

Edited June 8, 2011 by Gary A

[WarpSpeed]

It's called condensation from the evaporator and yes it is a normal part of proper operation. But in the case you described, though, it was solved with their recommended solution it was a symptom and not the actual problem, you just went around it but you should not have to use outside air to thaw it, it should work fine in all modes of operation without freezing.

Yes, of course it was a symptom. The car did not have the option of using outside air; there air was re-circulatory only and, depending on the sustained humidity within the car and the excessive demands placed upon the evaporator, these systems do ice up and restrict the re-circulatory air flow through the evaporator. This was the cause. The residual heat from the engine thawed the system and the drain.

Why does does the ride not have the use of outside air? Bordering on dangerous to use only in cab air.

Agree never heard of an OEM system being installed without a fresh air feature, only it being disabled by someone after the fact..

Edited June 8, 2011 by WarpSpeed

[WarpSpeed]

You experts think about this a bit. The inside air is already dehumidified. The outside air contains much more humidity.

The clutch? If the evaporator is freezing, the clutch must be working quite well. If the evaporator is freezing, that means everything is working too well. Obviously the system is delivering to much refrigerant to the evaporator.

Use the thermometer in the air duct.

I never disputed that, merely shooting down other misinformation..

[Naam]

You experts think about this a bit. The inside air is already dehumidified. The outside air contains much more humidity.

The clutch? If the evaporator is freezing, the clutch must be working quite well. If the evaporator is freezing, that means everything is working too well. Obviously the system is delivering to much refrigerant to the evaporator.

Use the thermometer in the air duct.

a conclusion that sounds logical but is most probably not the case Gary. fact is that lack of refrigerant is the common cause that ice forms at the evaporator on aircon units (applies to both car and domestic units). and that can happen also with a slipping compressor clutch as the compressor is meant to pump refrigerant at idle speed as well as at high engine rotations.

in case of too much refrigerant the condenser might not be able to liquify the gas sucked from the evaporator, the compressor is therefore not pumping liquid who's expansion in the evaporator provides the cooling effect by absorbing heat from the fan drawn air. no expansion, no cooling or not enough expansion = insufficient cooling but in both cases no ice forming.

[moe666]

As Naam said the evaporator freezing up is usually a sign of a low charge. The refrigirant changes from liquid to a gas futher into the evaporator causing the evaporator to freeze up unless of course it is a bad fan. There is a delicate balance going on in a a/c system

[GamLing]

Agree never heard of an OEM system being installed without a fresh air feature, only it being disabled by someone after the fact..

Well WarpSpeed, now you have heard of one. The early Mitsu G-Wagons and the Stradas (and other models from other manufacturers) did not have the option of choosing between re-circulatory air and outside air. My car was only 24 hours old when the problem occurred and the Mitsubishi dealer pin-pointed the cause immediately. The air-conditioning system and the drain just needed thawing; the car didn't even go into their workshop. I was asked to stop the engine and within a few seconds there was a deluge from the drain. Ten years on, I've never had the problem again.

These days, even with the choice, most car owners have the switches positioned on recirc air. The reason is obvious.