Refrigerator service diagnosis and repairs
Refrigerator Repair – Seven simple steps for service diagnosis
In order to diagnose any refrigeration fault quickly and accurately, a set procedure must be followed. The procedure described here takes the form of seven simple steps. If fully understood, these will prevent expensive call-backs and dissatisfied customers. No attempt to correct a condition should be made until the fault has been found, and therefore [...]
10Nov2009 | admin | 0 comments | ContinuedRefrigerator Repair – Noise
The sources of noise are numerous, and in some cases are entirely dependent upon the location and the type of building structure.
Common sources of noise are as follows:
1. Line rattles, that is pipework or control tubing vibrating against an evaporator or condenser shroud or framework.
2. Items of stored products (metal containers) or storage shelves vibrating.
3. [...]
Refrigerator Repair – System faults
Sealed systems such as domestic refrigerators and freezers need to be treated differently, since there may not be provision for fitting gauges unless line tap valves are used.
If the temperature control is by thermostat only and there is no low pressure safety control, continuous running of the unit will result if the system:
1. Is short [...]
Refrigerator Repair – Motor cycling controls: thermostats
Two types of thermostat are commonly used to control the temperature of a refrigerated space or product by stopping and starting the compressor.
The most popular is the vapour pressure type. This consists of a small bulb or sensing element containing a very volatile liquid charge. The liquid has the ability to vaporize at low temperatures. [...]
Refrigerator Repair – Pressure controls
There are many different makes of pressure controls. Designs may vary but the principle of operation is basically the same: single pressure models respond to either low or high pressure: dual pressure versions can be activated by both
high and low pressures.
Pressure controls are installed to perform a variety of functions. Most current production controls are [...]
Refrigerator Repair – Compressor motor burn-out: system flushing
Prolonged operation at high discharge pressures and temperatures, excessive motor starting, fluctuating voltage conditions, shortage of refrigerant charge and shortage of oil in the compressor are all possible causes of a motor burn-out.
A burn-out can be defined as the motor winding insulation having been exposed to a critical temperature for a long period.
Refrigerant thermal decomposition
This [...]
Refrigerator Repair – Water cooled condensers: scale and corrosion
Scaling
Any type of water cooled condenser is prone to scaling of the interior surfaces of the water tubing. The rate at which the scale forms will depend upon the condensing temperature and the quality of the water circulated. Scaling will be relatively low where condensing temperatures are below 38o C
Shell and tube condensers are fitted [...]
Refrigerator Repair – High side purging
Like low side purging, the practice of purging from the high side is also unacceptable and must be discontinued. When it is certain that non-condensables are present in a system a leak test must be carried out on the entire system and the leak repaired. If a plant has been recently installed or it has [...]
8Nov2009 | admin | 0 comments | Continued