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fatbillybob 09-08-2006 02:51 PM

I'm hot my suction line's not
First thanks for your help. I am familiar with auto A/C units not central air.

1-My pressure guages read 130psi on both hi and low side. Label on compressor reads 150psi low and 300 high. So it looks like my compressor is not doing its job or it is not coming on dispite my fan blades spinning.

2-A relay is kicking in but the fan blades do not spin unless I help it to get started then they spin just fine and I hear no bad bearing noises. This is unrelated to failure to spin due to too high head pressure on immediate shut down. I cannot get high head pressure as evidenced by problem 1 above.

3- Can the fan motor spin when the relay is switched on yet the compressor not run due to a clutching mechanism like in a car.

Besides getting a replacement unit what are the fixes? Is the no spin on the fan blades due to undiagnosised bad bearing friction or failure of a "high start capacitor assist"? Is there a pressure switch in Central A/c systems that sence the 130psi as too low a pressure such that it prevents the compressor from working similar to a car's low pressure switch that prevents the compressor from compressing nothing when the freon is too low.

oddjob 09-10-2006 08:43 PM

the 130 psi on your gauges means the compressor is not running, The fan does not have bearings it has bushings and adding oil to the bushings on the fan motor thru the oil ports (if it has them) might allow the fan to start on it's own again, but that would only be temporary. The compressor probably is not running due to an external high pressure switch or the compressor's internal thermal overload. My suggestion is to get the fan where it will start on it's own ie oil it or replace it and after the compressor cools off hopefully the thermal will reset, they usuallly do.:wink:

oddjob 09-10-2006 11:14 PM

One other item the 150/300 psi on the compreesor shell are test pressures:)

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