DTLarca
13-02-2013, 08:36 PM
When I started in the industry, back in 1985, a mini split sold by our company comprised, more or less, of:
Condenser coil, simple expansion device and evaporator coil.
Compressor with Starting Relay and capacitors.
Fixed-speed condenser fan motor.
Multi-speed evaporator fan motor.
C17 Thermostat.
Fan speed selector switch.
When a service call was called for all the motor windings were tested for continuity and insulation.
The fan motor's bearings could be easily tested by radial and axial play as well as rotational sound and resistance.
The compressor starting relay and capacitor were easy to diagnose as good or failed.
The compressor pumped or it did not - pretty much.
When an installing contractor bought a mini split they unhesitatingly accepted the burden of providing warranty labour - diagnostics and repair.
These days we have not just one PCB but often multiple PCB's.
We can check fuses for over current, varistors protecting for over-voltage (in turn blowing fuses). We can check thermistors and transducers and their connections. We can check rectification diodes and thyristors. We can check digital in-puts and out-puts.
But there are some faults that are now not easily discernible. We have those where our engineer on site is told by one of the dealer's techs that it is this PCB then their second tech says it is another PCB and a third says it is in fact yet something else. Our engineer then sometimes gives up and investigates on his own to find it was none of those suggested by the manufacturers techs.
There are those intermittent faults not caught by the operating software's overlay doing the system's self diagnostics.
It does not happen often. Maybe three times a year. But every so many months, when it does happen, I keep thinking I need to sit and start an article series on this matter in the magazines because it seems to me that it is no longer acceptable for the manufacturer to burden the installation contractor with these responsibilities.
I am now asking our engineer to word the job sheets explaining that since the problem with their unit lies somewhere extra to the limits of a basic electro-mechanical system we are not willing to suggest a remedy and are only willing to carry out the suppliers recommendations so long as the customer signs acceptance that we have, in no way, agreed nor disagreed, with the manufactures suggested next move and will expect to be paid for every parts change procedure the manufacturer from here on recommends.
We tell the customer the manufacturer has loaded the system with proprietary software and hardware in the form of PCB's but have not yet caught up with a diagnostics overlay capable of diagnostics, of some acceptable equivalence, as simple and as stupid as diagnosing an original C17 based mini split system - the manufacturer's use of these particular PCB's is, in this respect, premature - released before the necessary diagnostics overlay has become available.
If the customer has a problem with the costs they need to take it up with the manufacturer.
If the manufacturer wants to claim, to the end user, that the installation contractor must bare the burden then the manufacturer must show precisely what knowledge or skill the contractor is lacking. Since those problems I speak of cannot be discerned by either the contractor nor the manufacturer's techs the manufacturer would have failed, at this stage, to pass the buck.
Condenser coil, simple expansion device and evaporator coil.
Compressor with Starting Relay and capacitors.
Fixed-speed condenser fan motor.
Multi-speed evaporator fan motor.
C17 Thermostat.
Fan speed selector switch.
When a service call was called for all the motor windings were tested for continuity and insulation.
The fan motor's bearings could be easily tested by radial and axial play as well as rotational sound and resistance.
The compressor starting relay and capacitor were easy to diagnose as good or failed.
The compressor pumped or it did not - pretty much.
When an installing contractor bought a mini split they unhesitatingly accepted the burden of providing warranty labour - diagnostics and repair.
These days we have not just one PCB but often multiple PCB's.
We can check fuses for over current, varistors protecting for over-voltage (in turn blowing fuses). We can check thermistors and transducers and their connections. We can check rectification diodes and thyristors. We can check digital in-puts and out-puts.
But there are some faults that are now not easily discernible. We have those where our engineer on site is told by one of the dealer's techs that it is this PCB then their second tech says it is another PCB and a third says it is in fact yet something else. Our engineer then sometimes gives up and investigates on his own to find it was none of those suggested by the manufacturers techs.
There are those intermittent faults not caught by the operating software's overlay doing the system's self diagnostics.
It does not happen often. Maybe three times a year. But every so many months, when it does happen, I keep thinking I need to sit and start an article series on this matter in the magazines because it seems to me that it is no longer acceptable for the manufacturer to burden the installation contractor with these responsibilities.
I am now asking our engineer to word the job sheets explaining that since the problem with their unit lies somewhere extra to the limits of a basic electro-mechanical system we are not willing to suggest a remedy and are only willing to carry out the suppliers recommendations so long as the customer signs acceptance that we have, in no way, agreed nor disagreed, with the manufactures suggested next move and will expect to be paid for every parts change procedure the manufacturer from here on recommends.
We tell the customer the manufacturer has loaded the system with proprietary software and hardware in the form of PCB's but have not yet caught up with a diagnostics overlay capable of diagnostics, of some acceptable equivalence, as simple and as stupid as diagnosing an original C17 based mini split system - the manufacturer's use of these particular PCB's is, in this respect, premature - released before the necessary diagnostics overlay has become available.
If the customer has a problem with the costs they need to take it up with the manufacturer.
If the manufacturer wants to claim, to the end user, that the installation contractor must bare the burden then the manufacturer must show precisely what knowledge or skill the contractor is lacking. Since those problems I speak of cannot be discerned by either the contractor nor the manufacturer's techs the manufacturer would have failed, at this stage, to pass the buck.