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08 PT Cruiser blows warm air but never gets cold. Tried Freon but it doesn't blow cold or last long at all. It sounds like it's clicking on and off not too rapidly when driving it blow slightly cooler but never cold on max and while parked it blows hot air. It's summer in Texas and I'm sweating my makeup off.. any help would be appreciated.

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2 Answers

Sounds like the compressor is activating so you can rule out the Compressor Clutch and all associated electrical.

Place the A/C on MAX A/C and the Blower Speed on MAX. Once this is done, go under the hood and you'll most likely notice that the Condesor Fans are not spinning as they should be. If this fan isn't working properly then the A/C will blow warm whenever you are not moving and then the start to get cooler while driving. If the fan is not working then check for power at the fan motor. if there is no power then find out why (fuse, broken wire, bad fan) and repair as needed.

Note: These fans come on in other situations but with the A/C in these settings the fan should be on constantly

If the fan is working then there are a few other possibilities. - The freeon level is either too low / too high. Too much freon is just as bad as too little. It is bad practice to just fill it up with the Autozone trash. The system should be properly evacuated, vacuumed, and recharged to ensure that all moisture is removed from the system and there are no leaks in the system.

  • The Low Pressure Switch could be faulty. You can check for voltage at the switch by backprobing it or you could check for power at the pigtail. After wiring is checked and power is found then you can check resistance in the switch and determin it's functionality. _This switch is located on the Low Side of the A/C system. This switch is a normally CLOSED switch that will switch OPEN when the system is too low.
  • The High Pressure Siwtch could be faulty. This is checked in the same fashion as the Low Pressure Switch and is also a Normaly CLOSED switch that will switch OPEN when freon level is too high.

_These two switches turn the Compressor Clutch off (the cycling clicking you've most likely heard) in an attempt to protect the Compressor and System from further breakage.

  • The compressor itself is faulty and not compressing. It is possible that the compressor is being actuated and and it is not compressing anything. Anytime I've seen this situation there has been a horrible noise assosiated with it whenever the compressor was on.

A quick test for the switches can be done if you are certain the the system pressures are good. First, Locate the Low Side (should be on back against the firewall on the passanger side). Turn the A/C on and then unplug the sensor and with a piece of wire that is stripped on either end short the two terminals on the harness side. This will activate the compressor. If the pressures are good and all electrical checks out the nthe switch is bad. You can do the same thing to the High Pressure Switch. If both switches are bad then the A/C will only work if both switches are shorted

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I think you need more refrigerant ("freon"). Most modern AC systems have pressure sensors on both the high and low pressure sides of the system. If the high pressure side goes to high, or the low pressure side too low, the compressor clutch (and possibly fan) will switch off. When the system is really low, running the compressor just a second or two will get the low-pressure side too low, and it will immediately cut off, then cycle again. This can be very confusing if you have your pressure gauge attached, since when it cuts off, the pressure on the low-pressure side will shoot up above the target value, leading you to think it's fully charged. It's not. It's near-empty.

You can just unload a whole can into the system to get it partly working, then go by your gauge. What I did on a system I serviced just a couple days ago was pull off the electrical connector for the pressure sensor on the low-pressure side, and stick a paper clip across the terminals to keep the compressor from shutting off. Then I was able to monitor the pressure reliably as I added refrigerant.

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