With the problem you have described. We suspect that there are 2 compressors inside the condenser. One of the compressors might be faulty which leads to one of the split air-con unit not working.
What needs to be done is to first check for compressor’s running capacitor, this basically helps to start the compressor. If it is faulty, replace a new capacitor.
If the running capacitor is Ok, you might have a faulty compressor which needs to be replaced. If you have any further enquiry, feel free to contact us at 96192088.