My Haier HPY08XCM 8,000 BTU Portable Air wont cool. How do I troubleshoot?

Compressor has a problem internally.

Well I signed up for HVAC classes at the community college and that worked out well for me. Repairing your own system is a great reason to go to HVAC school, but it will probably cost more than replacing the unit you mention.

The thermostat isn't turning on the compressor. Check it out first. If it seems ok then check the wires going to the compressor. One of the 2 places will be the trouble .

A heat pump is an air conditioner that reverses its refrigerant flow. In the cooling mode, the evaporator is cold to the room and its condenser is hot. In the heating mode, a valve reverses the refrigerant flow and makes the evaporator warm and the condenser cold.

Check air filter and check the access water drainage pipe for any conjuction

I think you are asking about a portable air conditioner, not a de-humidifier. With that assumed, the answer is, NO - that is not a good idea. The exhaust tube is for getting rid of the heat that you have pulled from the room you are cooling, plus the extra heat that the device itself creates. This is a considerable amount of heat, which will quickly heat up the closet and leak back into the room you are trying to cool. If the closet it tightly sealed, the unit will not be able to push the air through the tube, and the unit itself will overheat. The result will be that you will be buying electricity to actually RAISE the temperature of the room you are trying to cool.

Dehumidifiers are designed to remove the moisture from the air not to cool. Unfortunately, the way they remove this moisture is to reheat the air to further dry it after it releases its moisture. Basically, the room temperature humid air enters the dehumidifier where it is cooled to its dew point which results in its releasing its moisture. This dried air is then heated by the combination of latent heat of condensation, which is a natural result of the process, and by circulating through the condenser where heat is exchanged from it to the air. The result is the air going back into the room will be slightly warmer than it was going in, usually around 2 to 5 degrees.

If your dehumidifier doesn't seem to run often but the humidity in the room is high, try adjusting the humidistat control on the dehumidifier to a dryer setting. If the dehumidifier seems to run constantly, but there's little or no water in the container, there may be a problem in the refrigeration system. Try cleaning the unit. If that doesn't work, you can't repair the refrigeration system yourself, you need a qualified appliance repair technician to do that.

Hope that helps! Should you have any further questions, please feel free to post them here.

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IrishDruid