Dear JB,
   
      My sister and I have the same problem with two different cars!  I drive a 1994 Chrysler New Yorker and she has a 1996 Dodge intrepid.  Both cars have had the same symptoms since last summer.  The air conditioning cools fine until suddenly - poof - all you get is hot air.  Of

course,  the cars have been just fine during the winter, so, like our father before us, we didn't want to waste money by getting them fixed then, but now that it is warming up again we need help.  My mechanic looked at mine and said that the system is full of refrigerant, but that the compressor suddenly disengages and that is why it is getting warm instead of cool.  He

is almost ready to recommend a new compressor but has suggested I get a second opinion.  What do you think?

Signed,
Chrysler Crisis

Dear CC,
   
So it's the old "my-compressor-cuts-out-at-idle" routine is it?  Well, good news, it's not a  compressor you need, Crisis, the problem is much more benign.  In front of your radiator there is another thing that also looks like a radiator.  That's your air conditioning's condenser.  The pressure can get pretty high in there, in fact, it can get dangerously high.  On your car (and your sister's)  the computer is in control of operating your compressor.  The way it keeps the pressure from getting too high in the condenser is to temporarily turn off the compressor and let the pressure drop.  Then it turns it back on and so on.  In order to do this there has to be some sort of sensor installed to

read the pressure.  In your case(s)  the sensor (called a pressure transducer) has failed and is lying to the computer by telling it to turn off the compressor.  Chrysler has released a redesigned part which will fix your problem. 

Dear JB,

      I drive a 1999 GMC Jimmy that appears to be haunted!  Have you heard of this?  One morning about two weeks ago, upon starting the vehicle, all the gauges registered fine and then dropped to zero for about 5 seconds. Several days later, the "Service Engine Soon" light came on for about a day, then went out with no driveability concerns. The following day, all gauges again dropped to zero and light came back on. This time, when stepping on accelerator, the vehicle appeared to rev up before actually moving (slipping or not engaging into gear?)  I visited my mechanic who scanned the computer for codes and found five different ones- all related to the transmission!  I thought these were supposed to be dependable vehicles, but it looks like I got a real lemon.

Signed,
Jumpin' Jimmy

Dear Jimmy,

    I wouldn't open up a lemonade stand just yet.  Your Jimmy is suffering in an epidemic of bad ignitionswitch-itis.    We see these outbreaks from time to time.  In your vehicle the same circuit which feeds the gauges  also feeds power to the transmission control solenoids.  On other models you sometimes see the heater blower quit working or another classic symptom is a car which will only run as long as you hold the switch in the start position (not a recommended procedure for getting back home from Florida).  I think that there is really just too much current flowing through the ignition switches of modern cars.  What was wrong with hand-cranks and 6 volt generators like we had in the good old days?!

JB can be seen each Thursday morning on WDEF-TV News 12's Morning Show at 7:30 A.M. where he answers your car questions.  He can also be heard Saturday Mornings 7-9 on Talk Radio 102.3 FM on the Saturday Morning Garage.  He spends the rest of his time taking advantage of helpless motorists at North Shore Auto Repair in Chattanooga.  E-mail JB at jeepster1515@yahoo.com to have your car care question answered in this column.