MY system has a full charge of refridgerant,still blows hot air. The thing I dont understand is why the compressor,while A/C is on,only engages for a short time,a few seconds,then disengages.Any one have this happen??? What should i check ??
Anything to steer me in the right direction would help...

 

They usually do that because they're low of Freon. It's caused by the low pressure cutoff switch operating when the low side pressure falls below about 20 psi. In normal operation, the low side should rarely go lower than around 35-40 psi. The switch is designed to protect the compressor from destruction due to inadequate oil circulation, since with the refrigerant that low, the oil doesn't get moved around through the system by it.

What makes you think it's full?

What are the high side & low side pressures, and at what ambient temperature were they measured?

 

The temp outside was probably 85 or so , but car was not driven far. It has R134 in it from a conversion. The guage on the loe pressure side was around 45.

 

The low pressure cutoff may be defective then. Try a new one of those. It's on the side of the accumulator, has a connector with some green wires.

 

Thanks....I will try that...

 

What was the pressure on the high side?

 

I did not have a way of checking that.

 

What tool did you use to measure the lp side?

 

Used the cheesie guage that came on the refill bottle..