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hilltop4527, Mechanic
Category: Chrysler
Satisfied Customers: 90
Experience:  I am an Owner/Operator with 15 years experience in almost all makes and models.
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chrystler 300c: compressor kicks on and off radiator fans do

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compressor kicks on and off radiator fans do not come on
Diagnostic Steps Performed/Parts Replaced
tested fans with scanner i am able to activate low speed and high speed with scanner no code in system i recharge system with
1.625 lbs REPLACED AC TRANSDUCER still fans not working
What kinds of pressure are you seeing on the gauges for high and low side pressure?
Customer: replied 3 years ago.

on the low side i am seeing about 40psi the high side varies it goes up till about 150 psi according to my ac machine. My scanner shows 65psi for refrigerant pressure.. i have charged the system with 36 ounces but when i turn the car on and ac on i activate the high speed fans with my scanner and the low side drops to about 20 psi to 10 psi

Thanks for that information. The transducer is set to not kick on the fans until high side pressure goes above 240PSI.
How often is the clutch cycling on and off? does it cool properly?
Customer: replied 3 years ago.

if i turn the high speed fan with the scanner it cools properly the compressor now is not turning off or on just on but it will open relief valve in a couple of minutes and let out all the freeon.. 240 psi on the high side right?

Yup 240 PSI is when the fan should be cutting on.
Customer: replied 3 years ago.

i am going to recharge the ac again and look at the high side how far it goes up until the relief valve opens up... is the high side of the fan controlled by the front control module and the low speed by the pcm?

I'm having some problems with my adobe program. I'm going to post the diagrams here for you. I would suggest checking for the 5 volt reference at the transducer and ground. You might also want to check continuity from the front control module to the transducer. I say this because the PCM should be kicking off the compressor before the high pressure relief valve opens.
Customer: replied 3 years ago.

i did check those wires one had 5v the other had ground and the third had 3.4v with connector disconnected.. i checked the pressure on the high side on scanner it got up to 211 psi high side and on the ac gauges it got up to about 215 and the pressure relief valve open in the compressor and let out all the r134 out again

Do you have a new relief valve you could swap out?
Customer: replied 3 years ago.

i dont have one but will get one tomorrow i just received more info on the car that they changed the expansion valve because it was not cooling enough

Sounds good just let me know what you find tomorrow. I'll be around all day.
Customer: replied 3 years ago.

i called the dealer they dont offer the pressure relief valve neither does the auto parts store

I hate to hear that. I'm going to open this up to my other fellow experts to see if anyone else has any thoughts. A fresh set of eyes can help. Some one should be with you shortly.
Hi I see you are having trouble with your A/C system. The previous tech is right. The high side switch is set to kick the fans on when the pressure reaches above 240 psi. If the relief valve is opening before the pressure reaches this point then the relief valve is bad. The relief valve shouldn't open until it reaches 400 psi or so. If the valve is not available your only options are to purchase a new compressor or to find a used compressor and use the valve from it. Thank you for using Just Answer.
Customer: replied 3 years ago.

i just order a compressor i will let u knw how it goes compressor was bought at auto zone new...

Let me know. Good luck
Customer: replied 3 years ago.

okay i replaced the compressor with an oem one and it did the same thing..

only thing I can figure is that you have a line restricted. And somehow the location of the restriction is not allowing the high side gage to read the right pressure due to it being restricted. All i know to do is start taking lines loose and blowing compressed air through them. Also check the orifice tube or expansion valve.
hilltop4527, Mechanic
Category: Chrysler
Satisfied Customers: 90
Experience: I am an Owner/Operator with 15 years experience in almost all makes and models.
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