another car problem

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  #1  
Old 08-21-07, 09:20 PM
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another car problem

here i am with another. My A/C keeps cutting out. it will blow cold air then all of sudden it will start blowing warm air. then after a minute it starts blowing cold air again. any ideas. took it to a repair shop they recharged the system and did a leak test and nothing was found. the tech could not recreate the problem. its under warrenty so if theres still a problem i can bring it back to the shop.could it be the compressor a a short somewhere or is it overheating.
 
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Old 08-22-07, 04:43 AM
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You didn't mention make/model/year.

When it starts blowing warm air is the compressor still engaged? If so you likely have a problem with your ducting system. In modern car ac systems, the heater core is always hot (unlike in the old days when you had a control that could effectively turn the hot water off to the core) and when you switch on the ac, the temperature coming out of the vents is controlled by moving the temp lever. What this does is control a door in the ducting system (mixing door) that mixes the hot and cold. When you want cold, the door is all the way closed to the hot heater core. If the system isn't operating properly this door may cycle without any input; it is frequently vacuum operated (but not always, my wrecker control is mechanical). If it's vacuum controlled and there's a problem, you can get what you describe.

If the compressor is cycling to off that is a different matter. One possibility is the thermostatic switch (and I may not have the name right). On some vehicles there is a switch with a sensor in the area of the evaporator core that senses if the core icing up; when this occurs the switch cuts the compressor out. On my truck this switch has an adjustment screw that can be turned so you get more or less cycling of the compressor.
 
  #3  
Old 08-22-07, 05:20 AM
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Originally Posted by flirty1 View Post
here i am with another. My A/C keeps cutting out. it will blow cold air then all of sudden it will start blowing warm air. then after a minute it starts blowing cold air again. any ideas. took it to a repair shop they recharged the system and did a leak test and nothing was found. the tech could not recreate the problem. its under warrenty so if theres still a problem i can bring it back to the shop.could it be the compressor a a short somewhere or is it overheating.
Are you in Florida????.........sorta funny but I ran across the very same problem in a Chrys Sebring here in Tampa.........Sometimes it would sometimes it wouldn't..........Kid who handled it first did exactly the same. Evac and recharge...........
Problem continued......
You need a scanner to check this ..........
WHEN you turn the A/C on you don't really.........You ASK the computer to turn the A/C on........
The control head signals the Body Control Computer.........which looks at pressure switches and such and if all is well signals the Power Control Module to drop ground to the compressor relay.........
Any loss of signal can cause what you're experiencing.........You need to have it in "failure" mode.........and search for where the signals stop
 
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Old 08-22-07, 05:30 AM
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Originally Posted by flirty1 View Post
. its under warrenty so if theres still a problem i can bring it back to the shop.
That shoud be all you need to know right there, you'd think. You already said it isn't working right, consistently.
 
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Old 08-22-07, 12:46 PM
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its a 96 Oldsmobile ceira SL. V6 3.1 liter. It was acting up before I took it to the shop. anyway how do I know if the compressors ingaged. it will blow cold then change to warm then back to cold.
 
  #6  
Old 08-22-07, 04:51 PM
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do you think the compressor might be going cause the tech could not recreate the problem so im assuming it happens while driving
 
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Old 08-23-07, 10:38 AM
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Locate the compressor and watch the face of the pulley/clutch; you'll be able to tell when it's engaged and disengaged. May need a second set of eyes watching while you monitor what's going on inside the car.
 
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Old 09-18-07, 08:35 PM
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another question the blower seams to make a cricket noise when the car is first started. after a minute it goes away. any ideas car has over 175,000 miles. im sure its nothing.
 
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