A/C problems.

[EclipzeGST303]

About a year ago my A/C died completely, it would blow air, but it was warm. I took it to a shop and it turned out to be a busted hose and of course no more coolant. Now I have another problem. Every time I drive it goes through a cycle.....Blows cold for about 2 minutes, then blows warm for about 10 minutes, then sometimes gets cold again, but not always.

What could this be? I have a squeaking belt, but I'm not sure which one, could it be slipping? Or does it just need recharged? But if it just needs coolant, it probably means theres a leak somewhere right? Since it was refilled just a year ago.

Thanks for any help.

 

[Defiant]

Sounds like a low charge symptom.

 

[GST with PSI]

Sounds like a low charge symptom.

I disagree with a low charge symptom...

A low charge symptom wouldn't produce any cold air at all.

If I recall DSM's use an FOT (fixed orifice tube) A/C system. This means the point of restriction which causes a pressure drop does not vary in size, but meters a constant amount of refrigerant rather than varying with evaporator temperature. In order to keep from flooding the evaporator with refrigerant, the compressor cycles on and off to keep the evaporator from turning into a block of ice.

Your A/C system also has a component called an accumulator/condesent. This device filters out any moisture in your system. The accumulator absorbs water vapor much like brake fluid does. For example, an accumulator absorbs water at such a high level, a brand new accumulator exposed to the atmosphere for 20 minutes is contaminated (saturated with water). This is why these items are sealed from the ambient weather when brand new. Think of this device like a sponge. It can only hold so much liquid before it will no longer absorb moisture. This same principal applies to an accumulator but at a much higher rate. An accumulator unlike a sponge however, can absorb moisture right out of the air.

A/C systems are sealed in the same way a brand new accumulator is. When a system develops a leak that system is no longer sealed. Atmosphere is now exposed to your system through the leak and your accumulator is now absorbing moisture from the air. Any time your system has to be serviced and is exposed to atmospheric pressure, the accumulator must be replaced due to contamination.

I am betting when your system was serviced the accumulator was NOT replaced. Your system was probably recharged with the contaminated accumulator, and was still slowly leaking (assuming they just recharged the system without repairing the leak) . Your accumulator is saturating your system with moisture. each time refrigerant passes through your accumulator it picks up some water and carries it with it. When your water saturated refrigerant gets to the metering device (FOT/point of restriction) it accumulates and freezes. you now have a blockage at the metering device. without refrigerant moving through the system your evaporator isn't going to get cold; hence warm air from your vents.

But why does it sometimes start to blow cold again? Well...
You now have an ice cube at your metering device right? On one side of the FOT you have a high pressure hot liquid. After that hot liquid passes through the FOT it becomes a low pressure cold liquid. Add water to this process and you get ice. Without flow through your metering device you no longer have a temperature/pressure drop. In other words your not making any ice without the refrigerant moving through the FOT. So picture this: You have an ice cube blocking the flow through your metering device, but have hot high pressure liquid pushing on one side. Obviously it's only going to take so long before your ice cube melts once again allowing refrigerant to pass through the FOT and letting the system once again work properly. The process then repeats over again. Freeze, melt, hot air, cool air.

My diagnosis: water in you A/C system due to a contaminated accumulator.

The cause: A leak to atmosphere.

The fix: Repair the leak, replace the accumulator, recover, evacuate and recharge the system.


Good luck hope this helps....