Well, I'm having a brain fart, whenever I turn the A/C or defroster on in my 95 f150 XLT(5.0) the idle goes from fine, to dropping down so low I think I'm going to stall. I charged the A/C in July and it never had this problem until recently. I hear the A/C clutch engage and disengage when it drops down so I'm wondering, did the r-134 leak and now the compressor is working extra hard or maybe the compressor is shot all together? Has any one encountered this, because this is a new thing and using the search feature didn't help >.<
Could it be something different all together?


P.S it doesn't do it when I turn on vent or floor... only when the a/c, mix, defroster is on

 

Turn on as many electrical loads you can besides engaging the ac compressor such as the headlights, wipers, blower motor on high, etc. Does the engine rpm drop down from the increased electrical load of the alternator?

All electrical along with A/C compressor loads are detected and is compensated by increasing idle via IAC valve. Both types of IAC's are made by Hitachi, the one that is a solid piece are not intended to be cleaned but if yours has two bolts that connect the electrical motor to the valve, the valve portion can be taken off and cleaned by itself with electrical parts cleaner. Do not use any harsh solvents as they may deteriorate the rubber components inside.

From my understanding when the PCM sees the low pressure switch closed, the PCM maintains the idle speed by the IAC valve. If this signal is not received, the idle will not increase.

If it is increased mechanical resistance in your AC compressor, you will know it real quick because it won't last long at that rate.