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2003 Pt Cruiser Ac Problems


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11 replies to this topic

#1 isus

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Posted June 16, 2006 at 10:59 am

I have a 2003 PT Cruiser 2.4L non turbo automatic

About 2 weeks ago the car would make some aweful noises and would shudder at idle when the AC was on. If you reved the car up in neutral and let off the car would stall and freeon would blow out of the high pressure valve. Well I took it to my brother in law (he is an ASE certified mech), he said that there is probably a blockage. Well we drained the system and check the lines and found that they all seemed to be clear. Then he tells me that my radiator fan is probably not comming on when its supposed to so the freon is not cooling off correctly and therefore not moving through the system like it should. This seemed to make sense to me because when I got on the freeway (which is most of my driving) the AC would work fine. So I take it to a local shop so they can recharge the system, and I also ask them to run a diag on it just in case. They tell me that the entire AC system works fine and that it must be an electrical issue. Well after looking over a ton of service manual stuff I found that the only thing that turns on the radiator fan is a combination of inputs from the speed sensor and the temp of the engine coolant. Well I had the headgasket replaced recently and I found that they replace the coolant with a 100% coolant mix; no water. So of course this would effect when the fan kicks on becuase coolant takes longer to heat up. Well so I figure I could just drain some coolant and add some water and problem solved. Not the case. yesterday I'm on the freeway and the AC is just blowing air not much cooler than ambient. So now I'm wondering if my compressor took a crap or if there really is a blockage that the shop did not detect. Is therre anyway that I can diag this myself with having to discharge the system? and should I take it back to that original shop and explain to them that their original diag was incorrect? I think this is a new issue unrelated to the first, however I don't want to have to pay the cash I think its going to cost to fix.

#2 AllanC

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Posted June 16, 2006 at 11:35 am

There is one additional sensor input that controls operation of the radiator / AC condenser fan. That is the AC system pressure transducer. This sensor is on the discharge refrigerant line of the system. It senses the pressure of the refrigerant which is directly proportional to the refrigerant temperature. That sensor and/or its wiring and/or its connector has failed. At low speeds and while stopped, engine idling, AC operating, this switch will engage the fan relay and draw air across the condenser. The reason for the refrigerant discharge and engine stalling was the fact that the sensor was not sending the proper signal to the powertrain control module (PCM) which in turn was not turning on the fan. The pressure increased in the AC system because of inadequate air flow across the condenser to such a level that the safety discharge valve opened and vented refrigerant. If the pressure transducer is functioning properly it should disengage the compressor clutch to prevent over-pressuring in the AC system and venting of refrigerant. To test this switch follow this procedure. Let the vehicle set for several hours minimum so that the engine temperature has cooled and the AC system pressure has stabilized. Open the hood. Start the engine, let it idle and engage the AC system. About 30 - 60 seconds after engaging the AC system, you should hear the radiator/condenser fan(s) turn on. If this does not happen, immediately disengage the AC system. The pressure transducer could be faulty and needs to be replaced. Or it is also possible that the radiator/condenser fan relay has failed. It is located in the power distributioncenter (PDC) near the battery. There is a legend under the lid. You can swap this relay with any other relay found in the PDC. Now because of the overpressure the AC compressor may be damaged. You need to have the suction and discharge pressures checked while operating to determine if the compressor is still functioning properly.

Edited by AllanC, June 16, 2006 at 11:37 am.


#3 isus

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Posted June 16, 2006 at 12:01 pm

The transducer is only on the turbo models. The realys are all good. The first thing I did was test them. I am a 12volt automotive tech I was able to rule out anything electrical. My issue now is that I'm not sure about the pipes and the other components of the ac system. the pipes are cold like they are supposed to be and the system is fully charged but I'm not getting cold air in the cabin at idle or when I'm on the freeway or when the fan is on.

#4 Bob Lincoln

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Posted June 16, 2006 at 12:28 pm

The transducer is only on the turbo models.

I think you'll find that, one way or another, the ECM turns on a cooling fan whenever the A/C compressor is on, for just about any MoPar in the last 15 years. Check your wiring diagrams again carefully.

#5 isus

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Posted June 16, 2006 at 01:55 pm

This is a direct quote from the DCX service manual for the PT Cruiser

"Non-Turbo
Radiator fan operation is control by the Powertrain
Control Module (PCM) with inputs from the temperature
of the coolant, which is sensed by the coolant
temperature sensor, and vehicle speed which is measured
by the vehicle speed sensor. The PCM turns on
the fan through either the high or low speed fan
relay. The PCM provides a ground to the relay’s control
circuit. The fan relays are located in the Power
Distribution Center (PDC) (Fig. 27). Refer to the
label beneath the PDC cover for location of fan
relays.
Refer to Radiator Fan Operation Chart for fan
operation specifications. For fan circuit wiring diagrams,
refer to WIRING DIAGRAMS."

here is the Radiator fan operation chart

RADIATOR FAN OPERATION CHART

Radiator Fan Control
Low Speed High Speed

A/C Off –vehicle speed < 70.8 km/h (44 mph)
Fan On: 96.6° C (206° F) 103° C (219° F)
Fan Off: 92.7° C (199° F) 98.8° C (210° F)

A/C Off –vehicle speed > 70.8 km/h (44 mph)
(until vehicle speed drops below 58 km/hmph)
Fan On: Off 103° C (219° F)
Fan Off: Off 98.8° C (210° F)

A/C On –any vehicle speed
Fan On: Off 82.2° C (180° F)
Fan Off: Off 80° C (176° F)



#6 Bob Lincoln

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Posted June 16, 2006 at 02:27 pm

OK. But do you have two cooling fans, one for the condenser? If so, perhaps there is a separate section describing that.

#7 AllanC

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Posted June 16, 2006 at 02:31 pm

This is another situation in which one is familiar with wiring and components that determine AC operation over a period of years. And then the manufacturer changes things and one's diagnosis is based on outdated information. I checked a factory service manual for a 2003 Neon and researched the AC system on that model. It should be similar to the 2003 PT Cruiser. The pressure transducer that I mentioned is no longer used in the system. There no longer is an evaporator temperature sensor for compressor clutch cycling control (left hand drive models only). Compressor clutch cycling is controlled by a low pressure switch on the accumulator. There is a high pressure cutout switch on the compressor that is supposed to signal the PCM to disengage the compressor clutch if AC discharge pressure exceeds 470 psi. For some reason that did not function properly on your PT Cruiser and allowed refrigerant to vent. Engine radiator and condenser fan operation is controlled by the PCM with inputs from the engine coolant temperature, AC operation and vehicle speed. So instead of using the AC discharge pressure to directly control operation of the fan(s), there is logic in the PCM which turns on the fan because forward speed has dropped below a certain threshhold when the AC is operating. I now wonder if the distance/speed sensor is functioning properly. If that is not giving a proper signal to the PCM, the PCM would be fooled and not turn on the radiator/condenser fans at low speed or at idle. Do you have cruise control? Does the cruise control work? If the cruise control works then the distance/speed sensor should be functioning properly. If the AC system is functioning with about equal and cold temperatures on the input and output lines from the evaporator at the firewall, then the only other source for no cooling is a problem with the blend air door in the AC / heater box under the dash. When you operate the dash AC temperature control from hot to cold do you hear the blend air door move?

Edited by AllanC, June 16, 2006 at 02:33 pm.


#8 isus

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Posted June 16, 2006 at 05:14 pm

My brother in law is on the way over right now to check out the door. I've been tearing apart the dash all day. Just need to get the steering wheel off now.

To answer the previous post...I have one fan.

As far as hearing the door...my sense of hearing is less than par, so I can't really tell. When I know what is going on for sure or if we get stumped I'll post again. This car has been one headache after another.

#9 isus

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Posted June 16, 2006 at 07:25 pm

All right we are stumped! All of the lines are cold...ice cold, the block on the firewall is also cold. The evap core not all that cold. All of the hvac doors are functional and operating correctly. Does it sound like I have a blockage or do you think the evap core is clogged up or bad? My fiance really needs this car fixed asap.

#10 AllanC

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Posted June 16, 2006 at 11:51 pm

You need to check the suction and discharge pressures on the system while it is operating. Typically if there is a blockage in the AC system, the line is warm on the upstream side of the blockage and cold on the downstream side. Follow the line from the condenser outlet to the evaporator. See if you can find a spot where there is a significant temperature difference. Chrysler started using a variable orifice valve in the discharge line sometime in the last 5 years instead of an expansion valve on the inlet to the evaporator. There should be a temperature difference in the area of the in-line orifice valve.

#11 isus

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Posted June 17, 2006 at 12:14 pm

Well my brother in law got some freeon in the car yesterday and the car started giving me some cold air. Since I just had the thing recharged he is assuming I have a leak. I'm going to take it up to his shop Monday and he is going to do a leak test and then order the part for me that is bad. thanks for all of your help;

#12 AllanC

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Posted June 17, 2006 at 07:50 pm

One location to check for a refrigerant leak is the pressure relief valve on the compressor. You indicated that the system did vent refrigerant. Sometimes the valve does not reseat properly and that could cause a small leak. It is located on the end of the compressor opposite the pulley.


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