air conditoner air filter

[5ducks]

I was wondering if anybody knew if it makes any difference on which air filter to use? I took out the foam pad that came with the unit and cleaned it and let it dry. I had some top quality home filters that I decided to cut to fit and install. I turned it on and it sure seemed to flow air and cool much better. Later, the unit froze up, and I suspect it was too much air flow for the unit to handle. I would appreciate any information on this. Thanks Gary

[cjensen91910]

Normally, it's not enough air flow that freezes a unit up. The air does not remove the moisture from the coil fast enough letting it get down to the freeze point. I used a piece of impregnated active carbon foam on mine and works OK. Removes a slight bit more dust.

[docj]

Actually, A/C freezing is often a symptom of LOW (that's right, low) refrigeration levels. I've had this happen at home and in cars a number of times. I'm sure someone here can provide a technical explanation for this.

[5ducks]

Quote:

Originally Posted by docj Actually, A/C freezing is often a symptom of LOW (that's right, low) refrigeration levels. I've had this happen at home and in cars a number of times. I'm sure someone here can provide a technical explanation for this.

Thanks for the help and information on this issue. I am taking unit in Tuesday for a long list of items for service and this is one I will have to add. Warranty runs out next month, gotta get my last licks in while I can.

[TXiceman]

Quote:

Originally Posted by docj Actually, A/C freezing is often a symptom of LOW (that's right, low) refrigeration levels. I've had this happen at home and in cars a number of times. I'm sure someone here can provide a technical explanation for this.

9 times out of 10, the problem of an RV A/C freezing is low air flow due to restricted filter, restricted evaporator coil or internal by passing.

What actually occurs in basic terms is the lower air flow results in less load on the coil which causes less refrigerant to boil into gaseous form. The compressor is either a piston or scroll type and is know as a positive displacement compressor. This means that the compressor will pump a given volume of refrigerant (CFM or cubic feet per minute). The compressor continues to pump a given volume of refrigerant and as this occurs, the specific volume of the refrigerant is reduced and the compressor and evaporator coil will reach a new balance point. Due to the physical properties of the refrigerant, the pressure in the coil is now lower and the temperature is also lower. It will continue to reduce the temperature until the temperature in the coil and the coil surface is below freezing.

In a case of low refrigerant, there is insufficient refrigerant and the pressure drops in the coil until the temperature is below freezing.

An RV A/C unit is not prone to leaks and most freeze ups are due to low air flow for one of the earlier stated reasons.

I have seen home units low on refrigerant as well as ones with dirty filters....both cause a freeze up. It takes a technician with basic trouble shooting skills to determine which is the problem.

But to immediately say it is low on refrigerant is really misleading.

If anyone is interested, I can teach a very basic A/C course at a Texas Boomers rally.

Ken

[RJay]

Usually, the more expensive filters will filter out smaller dust particles without reducing airflow much. The cheaper filters have good airflow but allow larger dust particles to pass making the unit become less efficient and contributing to poor air quality. There are places to save money but this is not one of them.

[5ducks]

Quote:

Originally Posted by TXiceman 9 times out of 10, the problem of an RV A/C freezing is low air flow due to restricted filter, restricted evaporator coil or internal by passing. What actually occurs in basic terms is the lower air flow results in less load on the coil which causes less refrigerant to boil into gaseous form. The compressor is either a piston or scroll type and is know as a positive displacement compressor. This means that the compressor will pump a given volume of refrigerant (CFM or cubic feet per minute). The compressor continues to pump a given volume of refrigerant and as this occurs, the specific volume of the refrigerant is reduced and the compressor and evaporator coil will reach a new balance point. Due to the physical properties of the refrigerant, the pressure in the coil is now lower and the temperature is also lower. It will continue to reduce the temperature until the temperature in the coil and the coil surface is below freezing. In a case of low refrigerant, there is insufficient refrigerant and the pressure drops in the coil until the temperature is below freezing. An RV A/C unit is not prone to leaks and most freeze ups are due to low air flow for one of the earlier stated reasons. I have seen home units low on refrigerant as well as ones with dirty filters....both cause a freeze up. It takes a technician with basic trouble shooting skills to determine which is the problem. But to immediately say it is low on refrigerant is really misleading. If anyone is interested, I can teach a very basic A/C course at a Texas Boomers rally. Ken

Thanks Ken and everyone else who replied. Wow, that was a great explanation on the operations of rv air conditioners. If I ever get to one of your rallys, I will look forward to more...thanks gary

[Ray,IN]

I used "Filtrete" brand sheet filter material, found at WalMart, and most any good hardware store. The problem with this sheet material is it is so light the fan will suck it up into the fan blades. You must construct a wire frame (kinda like a tiny woven-wire fence) to hold it in place. Now that I installed aGenesis Micro-Therm Air Filtration System I never have to contend with my home-made filter and restraining wires.