[speedball1]

OK! Now that I have your attention here's my question. 20 years ago I swapped out my old pot type oil burner for a air handler and heat strip. I still kept the wall banger AC. Six months ago my wall bangers compresser took a dump. I contacted one of my old AC foreman buddies that I worked with out in the field that had his own business going. He gave me a deal on installing a new 2 ton Goodman AC unit outside and using the cooling coils and fan in my old air handler. I was told the two were compatible. Here's my problem, (took me long enough to get to it didn't it?)
The AC unit's 13 Seer and the air handler's 8 Seer. The AC units compressor will shut down but the AC units fan and the air handler fan will still keep on running blowing cool air until the compressur kicks back in with refrigerated air. Why does this happen? Does this injure the compressor? It's benn giving me cold air ever since it's been installed with no problems but I'm concerned that the compressor may be overheating and throwing the overload breaker and then cooling down and restarting. There's no "hot motor winding" smell around the unit outside and 6 months later the air is still cold. Hoiw bad off am I? Thanks, Tom aka speedball1

[acetc]

Speedball 1 , it sounds like the compressor may be kicking off on either the internal overload in the compressor or possibly a safety switch. Your unit may have either a high or a low pressure switch in the outdoor unit, You can tell by removing the acess panel and looking for a small pressure switch on one of the refrigerant lines, this switch will have two wires coming from it.
To tell if it is a high or low pressure switch, if it is attached to a 3/8's line it is a high pressure sw. if it is attached to a 3/4 or 7/8 line it is a low press. sw.
If it is going off on the high press. Switch this may indicate a dirty condenser coil, bad condenser fan motor, or an overcharge of refrigerant, if it is going off on the low pressure sw. this would indicate a low charge.
If it is going off on the internal overload in the compressor it normally would take hours to cool down and restart, so this may not be your problem. THe high pressure swich shutting it down is serious to the life of the compressor. Feel the small line leaving the condensing unit while it is running, if this line is very hot then suspect the overcharge option. Hope you the best and good luck, MIKE

[speedball1]

I was told by the installer that the difference in Seer numbers was the cause of the compressor cycling off and on.
" Feel the small line leaving the condensing unit while it is running, if this line is very hot then suspect the overcharge option."
The small line runs cool when the compressor's running. Thanks again for your input. Tom

[hvac1000]

You can run a 8 SEER and a 13 SEER combination. You really need a expansion valve to do this properly. If your unit is equipped with a piston type flow rater it will not meter the refrigeration correctly. The metering of the refrigerant is critical for proper operation and to max out the life expectancy of the equiptment.

When you install the expansion valve also ad a hard start kit and a time delay to the outside unit. There is a long explanation for this but my fingers would wear out from typing if I tried to post it. To use simple terms a 13 SEER outside unit is looking for a much larger coil than the 8 SEER unit inside has so it will not operate properly or give you the extra energy savings a 13 SEER coil would afford.

The piston selection for metering will be just about impossible to determine so this is why I suggest a expansion valve. The expansion valve will prevent the outside unit from loading up with unevaporated refrigerant since the inside coil is not large enough to evaporate it all. This inturn causes liquid refrigerant to flow back to the outside unit in the suction line and plays hell with the compressor eventually causing it to loose its valves or washing the oil off the bearing surfaces causing it to lock up. Either way the compressor becomes toast and you can buy a new unit.

The expansion valve helps to prevent this. Make sure when you get the valve to get a external equalize type. This has much better flow control than ones with out the external equalization.