The owner of a 2014 Corolla may come into your store with a complaint that his air conditioning system on occasion won't cool properly at idle.
One possible cause for the trouble, according to Toyota, is a defective a/c compressor. Replacing the compressor with an improved design unit, part No. 88310-02851, may eliminate the cooling complaint.
To find out for sure, connect a scan tool, cycle the a/c button and look at the regulator control current, regulator pressure sensor and evaporator fin thermistor items in the data stream while the problem is occurring.
If the control current is .7 amps or higher, the regulator pressure is low and steady, and the fin thermistor reading is higher than normal and increasing, that confirms that the original compressor has an internal defect and should be replaced with the updated model.
If all three data items don't match up with the conditions noted above, this information doesn't apply. Continue with conventional troubleshooting until the cause of the intermittent cooling complaint is found.
"Factory Fixes" is written by Jim DePalma, a 30-year veteran of the auto repair business who has served stints as a service manager, parts manager and ASE-certified technician. His column provides vehicle manufacturers' authentic factory technical service bulletins (TSBs) that have been condensed for easier reading. Mr. DePalma advises that techs always check with a dealer or repair information system for the latest revisions before starting to work on a vehicle. He can be reached via e-mail at [email protected].