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Dan, ASE Certified Technician
Category: Dodge
Satisfied Customers: 1568
Experience:  Auto Technician
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Not getting power to compressor, 2009 dodge grand caravan

Customer Question

Not getting power to compressor
JA: What is the model/year of your Dodge?
Customer: 2009 dodge grand caravan 4.0
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: New compressor new condenser cause it was leaking. Vac'do for an hour recharged compressor won't kick on. Have power out of both 10 amp and 20 amp fuses
JA: How old are the hoses? And what driving conditions do you most often encounter?
Customer: Live in pa
JA: Anything else you think the mechanic should know?
Customer: Clutch on old compressor locked up. Vac'do system and unplugged power from compressor so it couldn't accidentally engage. Fuse box doesn't show a relay. Wanting to know if it has one
Submitted: 6 months ago.
Category: Dodge
Expert:  Dan replied 6 months ago.

Hello my name is***** am an ASE Master Technician and I am glad to help you out with your question.

Customer: replied 6 months ago.
Need to test to see why compressor is not getting power. Is there a relay also or just 2 fuses for AC
Expert:  Dan replied 6 months ago.

First, there is no high and low pressure switch on this system. It uses the AC pressure transducer located on the Filter dryer under the hood on the passenger side.

The computer disengages the A/C compressor clutch when high side pressure rises above 447 psi and re-engage the clutch when high side pressure drops below 426 psi. The A/C pressure transducer will also disengage the A/C compressor clutch if the high side pressure drops below 16 psi and will re-engage the clutch when the high side pressure rises above 32 psi.

Check to see if the PCM is sending a signal to TIPM to activate the AC compressor clutch. If so and the AC pressure transducer is working, then chances are the TIPM is at fault. However, the AC pressure transducer could be giving faulty readings as well.

Two other sensors also could be a problem. The sun load sensor and the evaporator tempature sensor.

Expert:  Dan replied 6 months ago.

Based on my experience, if you jumper the Pressure transducer and the Compressor comes on, either the system is low on freon or the Pressure transducer is bad and needs to be replaced. You have indicated that the freon is full so that would only leave the pressure transducer.However, if the AC compressor still does not come on then I would suspect a bad sun sensor or evap temp sensor.IT is possible that the HVAC head unit is bad also. However, this should set a code.Check the A/C pressure in the data stream. This should match close to the actual pressure in the system. You can also see if the PCM is able to activate the AC relay by running the Actuator Test for the A/C relay. When you do this, it should turn the clutch on and off. Also, if your scanner can communicate with the automatic temperature control unit, check to see if there are any codes stored in the unit.Be sure that the evaporator temperature sensor in the Automatic Temperature control system is reading the same temp as the evaporator core.

Customer: replied 6 months ago.
Unclipped connector and tested the 3 pins of the low pressure sensor and all gave readings. Not sure what combinations kick compressor on but all gave readings
Customer: replied 6 months ago.
Which relay is for AC? Both the fuse lid and book don't show one. Just a 10 and 20 amp fuse
Expert:  Dan replied 6 months ago.

Its integrated into the TIPM

Expert:  Dan replied 6 months ago.

You can jumper the light blue orange wire to the light blue brown wire at the AC pressure transducer with the AC turned on to see if the AC compressor comes on.

Expert:  Dan replied 6 months ago.

Please reply to this if you need more help and we can continue this conversation. If you are satisfied with my service, please rate at the top of the screen. Rating does not close out your question. Remember, sometimes it is difficult to completely diagnose your vehicle without being there, but I will try to give you the best answer I can. If I am not giving you 5 star service, please let me know what I missed.



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