The big suspects are the TPS (throttle position sensor) and the MAF (mass air flow sensor). Also, you could have an air leak in the intake path.
It is possible that the code that was received was misinterpreted to be a problem with the A/C. Having said that, continue to the real diagnostics.
The TP sensor will set a code if it malfunctions - but not every time. If the sensor sends the PCM a "dirty" signal, it can cause hesitations. This is a good place to at least check. Check for dirty connections or corrosion on the connections.
Then there is the Mass Air Flow sensor and associated ductwork. The purpose of the mass air flow sensor is to tell the PCM how much air is entering the engine at any given time. The PCM then admits the proper amount of fuel to combine with that air to achieve the proper mixture. Any leaks of unmetered air into the engine will disturb that "perfect" mixture. Check for any kind of vacuum leaks. Examine the PCV and brake booster lines in particular. Examine the duct that goes from the MAF to the intake of the engine. Air leaks in that area are cause for major driveability problems.
Also, be warned that if the MAF goes out of calibration, in MANY cases, it will NOT set a code. If the signal it sends to the PCM is within a reasonable range - even if it is incorrect - the PCM will be satisfied, and will not set a code.
Hope this will be of some help to you. Good luck!
Thursday, March 26th, 2009 AT 4:02 PM