steamup wrote:Any appliance that has a problem with the refrigeration circuit is probably more costly to repair than to replace.
If the compressor is running but stopping, it is probably dropping out on a thermal limit. Check to make sure the condenser is not blocked or dirty. Blowing it out with compressed air may help if it is dirty.
Make sure the inside air filter and coil is clean also. Wash the filter and Vacuum the coil off if dirty.
It may not be a refrigerant problem. It just may be too overworked with the extreme temperatures.
Window A/C units are made for a very competitive market place. A ten year old unit isn't worth repairing and a new unit will be more efficient on energy.
Repairing small residential A/C appliances was a frequent topic in my HVAC classes. Often a student brought a window A/C, dehumidifier or dorm sized fridge for repair. Cleaning was step #1. A power wash with detergent followed by a chemical foam to clean the evaporator and condenser coils. Sometime this alone returned the units to working condition. Since appliances don't have Schrader valve ports for connecting pressure gauges they need to be added. This is done by piercing the refrigerant line and using it to remove all of the remaining refrigerant. For a licensed HVAC tech this requires a refrigerant recovery machine. Since a homeowner is not normally licensed he usually just vents it. Not exactly illegal for him to do it assuming it's a "small" amount. Then a line Schrader valve is brazed in, usually two one on the high side and one on the low side. Ideally nitrogen purging is used while brazing. The line where it was punctured is repaired or replaced. Then the unit is nitrogen pressure tested. Assuming all is well it's vacuum evacuated and charged with refrigerant. Ideally with the original refrigerant type. If using a replacement refrigerant, you need to understand the operating characteristics of the replacement refrigerant and make some adjustments. This could be do nothing, to replacement of the cap tube to a different size. Many of the replacement refrigerants operate at higher pressures and equipment failure at the higher pressures is a possibility. Propane refrigerant is frequently mentioned. The hazard is often overstated and not understood. In small quantities it is a safe refrigerant. It is approved for home HVAC appliances in Europe.
Henry Technologies is the manufacturer of many of the tools need to repair small units. You can find their catalog here:
Look under catalog, - > then A1 Components Parts, -> then Valves, Line Tap.
Also look at "Access Fittings", these are the Schrader valve ports you braze in. These are sold by HVAC supplies houses in packs of 3, 5 or 100 depending on size. To give you an idea of prices my wholesale house sells a basic line piercing type for $2.74. Schrader types are slightly more expensive.
All this said it's seldom cost effective to repair a small HVAC unit. It's takes skill, tools and craftsmanship to return it to like new operation. It's just cheaper to buy a new unit.