I have a big problem

[cwilson]

Bought a brand new house with two Trane Heat pumps. ONe has worked perfectly from the get go, the other has been problem after problems with an overheating compressor. After lots of patching up, the compressor finally gave after 5 years and 6 months (warranty gone), so I buy another unit. After install, it is working great, and then after working for about 6 hours, the compressor shuts off. I can get it to come back on if I run water over it.

Too make a long story short, the AC guy figures it just had a bad compressor in the new unit, so he puts another compressor in. Same thing. Works great for about 4 to 6 hours and then shuts down in the heat of the day. No problems running the unit at night.

What can cause a brand new compressor to overheat. Everybody that comes out looks at the outside unit. There is clearly something going on with the other parts of the system in the attic, in the ductwork? The filters are clean. I am smart enough to check that, but I can't get to the root of this problem.

Help. I have had 10 AC guys look at this. They usually run water ovr my compressor for 10 minutes and charge me $100. I need to find the problem and the professionals are not finding it.

[Freon]

I will assume the new condenser is not a refurbished unit and therefore the coil and fan are OEM. I will also assume there is a clear area around the condenser so air flow is not restricted. The cooling for the compressor usually comes from the returning refrigerant from the indoor evaporator coil. I would check the temperature of the suction line at the condenser. I would also very carefully check the electric circuit to the condenser from the main breaker panel. A poor/loose connection/breaker can cause a voltage drop thereby raising the amps being drawn by the condenser and generating heat. Tighten all screw connections and twist any wire nuts AFTER you turn off the power at the main breaker.

[logoschoen]

Has anybody ever thought about an oil return problem coming back to the compressor making it overheat? Just a thought, but with having three or so compressors, its definitly not a coincidence. Its either starved for refigerant and not cooling the compressor, a loose or bad connection on supply voltage to the compressor as stated above, or possibly starving for oil return. you may want to change the company you are using, and ask the new company for a senior technician.

[Freon]

I would first check the compressor amperage draw when everything is running and compare that value to the data plate value on the compressor. I would replace the run capacitor. If there's a hard start capacitor I would replace that also. Capacitors are inexpensive yet can cause big problems. Be very sure you use the correct capacitance values as stated by the manufacturer. Then if there's still overheating I think Logoschoen has a good idea. Check the lineset for any unusual dips or other abnormalities that could cause oil not to circulate as it should.