I have got a brand new goodman unit. The motor kept stopping after few hours an the tech replaced the motor. It still had same issues.. I was told that the voltage coming into the unit is too high.. The voltage was around 246-249v. The unit itself says it supports a max range of 253 volts. however the motor on the unit supports only 230 volts.. The hvac guy disappeared for 2 days and it is not working out. He suggested me using a step down transformer. Is that the only way out of this? Shouldn't goodman be providing a capable motor that runs in the max range supported by the unit?
thanks for all the answer guys.. finally resolved the problem. It was due to incorrect wiring.. Explanation from the guy who fixed it.. Instead of plugging in 220 v to the fan, they plugged one end of the hot via the capacitor.. So it was able to run only for sometime till the capacitor drains.. Once it reaches 120 v it is not able to keep up and the fan stops.. I can try to get more details if needed..
When the nameplate of a motor says 230v, it actually means 230v +- 10%. So the absolute maximum voltage rating of that motor is 253v (10% above nominal). That assumes the motor is also designed for the same frequency power that you have. For example, in the US the power frequency is 60Hz and the motor also needs to be rated 60Hz in that application.
I cannot tell from your question which motor in the a/c system you are referring to. The possible causes of your problem vary greatly depending on whether you are having problems with the blower, compressor, or condenser fan.
Ask an Electrician to install a Buck Boost Step-Down Transformer.
They commonly look like:
A common wiring diagram will look like:
Ensure the transformer has an amperage rating that equals or surpasses your HVAC/R Unit. The Electrician doing the install will have the expertise to install the proper one the proper way.
Chris is correct, that induction motors (such as a blower/fan) has a "range" of + or - 10%, and if you are supplying voltage that is within that range, you should have no problem. However, you are supplying a pretty high range to begin with and does not leave very much room for voltage fluctuations throughout the day.
This is also why it is common for a water heater to have a buck boost transformer, to assist with voltage fluctuations for safety and reliability.
There are two main byproducts of electricity: Heat and Magnetism. The longer something runs, the warmer it gets. The warmer it gets, the more resistance on the circuit. The more resistance on the circuit, the lower the current and the higher the voltage. It is a vicious cycle.
I would also ask that Electrician what your power supply is from the utility company. If your voltage is running higher than 220VAC in most countries, and higher than 240VAC in other countries, then something could be wrong and could start effecting other equipment within your home.