Air Conditioning Diagnosis
Typically, when your air conditioning breaks, the system still blows air, but that air is not cold. The most likely cause is a refrigerant leak, but it could be another issue, such as a faulty air conditioning compressor.
In most cases, testing the air conditioning system with a set of manifold gauges is the first place to start troubleshooting. A mechanic will attach the gauges to the high and low sides of the system, retrieve the pressure readings, and use those readings to help diagnose any problems.
If the gauge readings indicate the system is low on refrigerant, an “evacuation and recharge” process will likely be recommended. It includes the following:
- Recover the refrigerant lines to see how much refrigerant is remaining in the system
- Evacuate the system of air and moisture
- Fill the system with brand new refrigerant to specification
- Insert a color dye which will help more easily reveal the source of the leak
If the leak is very small, then it may not be observed for many months from now. If the leak is catastrophic, then the refrigerant may not last more than a few minutes while the car is still in the shop. In either case, the evacuation and recharge process will help us determine the best next steps, and in the case of a very minor leak, you may actually be all done for a while.
If you don’t have a leak at all, the evac and recharge process will still allow the technician to observe the system try to operate in an ideal environment, and help indicate the next spot to look. For most A/C repairs, you would need a recharge anyway, so it’s also probably a relevant repair.
Could it be something else?
Sure, other symptoms might include an issue with your blend door or blower motor. The symptoms for these issues are usually a bit different. If your air conditioning isn’t blowing any air at all, then the issue could be the blower motor, which might be diagnosed differently. If it’s blowing hot air instead of cold air, then the issue could be a blend issue, which helps your heating and air conditioning system switch off between hot and cold air. For both cases, it might be that the technician still needs to start with an air conditioning evac and recharge to find the issue; your service advisor is probably the best person to ask about your specific case.
A mechanic quoted me a really low price for an A/C diagnostic. Why?
Yes, we have found that some places offer low cost AC diagnostic, but those are generally visual only, and then end up recommending a more expensive evac and recharge. At RepairSmith , we think it is important to be as upfront and transparent as possible, so we present the full diagnostic cost to you upfront.