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Discussion Starter #1
Engine cooling fan not working. 2005 PT Cruiser touring (POS model) :). The A/C worked great for about an hour, the lines to the compressor were ice cold, then got really hot, after that...NOTHING. New head gasket, new cooling fan (6 months old) new water pump and timing belt, new radiator, new thermostat, new low pressure switch for A/C. All of the relays check out OK including a new one for the low speed fan. Code 0480. Fan does not come on when A/C is activated. Compressor used to cycle but now does nothing. Does not overheat. I have no idea what else to do.
 

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To properly diagnose the problem you will need a scanner.
P0480 CHRYSLER - Cooling Fan 1 Control Circuit...Possible causes; Faulty fan control relay, Fan control relay harness is open or shorted, Fan control relay circuit poor electrical connection, Faulty cooling fan 1, Fan cooling fan harness is open or shorted, Fan cooling fan circuit poor electrical connection...Description; The electric cooling fan is controlled by the Engine Control Module (ECM) through the cooling fan relay based on inputs from the following components: - The engine coolant temperature (ECT) sensor - The intake air temperature (IAT) sensor - The A/C selector switch - The A/C refrigerant pressure sensor - The vehicle speed sensor (VSS) The ECM controls the cooling fan by grounding the cooling fan control circuit which turns ON the cooling fan relay. The cooling fan relay will be commanded ON when the following conditions are met: - The engine coolant temperature reaches 106°C (223°F) or more. - The A/C clutch requested. - The vehicle speed is less than 38 MPH. The cooling fan relay will be commanded ON regardless of vehicle speed when the following conditions are met: - The engine coolant temperature is 151°C (304°F) or more. - The A/C refrigerant pressure is high. The cooling fan may be commanded ON when the engine is not running under a fan run-on conditions described in the electric cooling fan general description portion of the service manual.

 

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Thank you NAJ! Update: After messing with this for a while, the compressor cycles and the A/C works although not very cold. The engine cooling fan still does not come on as it should when A/C or defrost is on (with the engine off). FYI, we did not just throw parts at this. I bought it from a relative knowing it was time for a new timing belt, water pump, etc. Maybe you or someone has experienced this: When I first start this car, there is a loud "POP" from under the hood. This happens every time. The car sat for 2 years due to overheating issues, so I have been dealing with corrosion issues as well. The fan stays on now when the A/C is on and then works normally when I turn the A/C off, meaning the fan cycles on and off as the temp rises. I think the car may be haunted, LOL.
 

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Discussion Starter #4
To properly diagnose the problem you will need a scanner.
P0480 CHRYSLER - Cooling Fan 1 Control Circuit...Possible causes; Faulty fan control relay, Fan control relay harness is open or shorted, Fan control relay circuit poor electrical connection, Faulty cooling fan 1, Fan cooling fan harness is open or shorted, Fan cooling fan circuit poor electrical connection...Description; The electric cooling fan is controlled by the Engine Control Module (ECM) through the cooling fan relay based on inputs from the following components: - The engine coolant temperature (ECT) sensor - The intake air temperature (IAT) sensor - The A/C selector switch - The A/C refrigerant pressure sensor - The vehicle speed sensor (VSS) The ECM controls the cooling fan by grounding the cooling fan control circuit which turns ON the cooling fan relay. The cooling fan relay will be commanded ON when the following conditions are met: - The engine coolant temperature reaches 106°C (223°F) or more. - The A/C clutch requested. - The vehicle speed is less than 38 MPH. The cooling fan relay will be commanded ON regardless of vehicle speed when the following conditions are met: - The engine coolant temperature is 151°C (304°F) or more. - The A/C refrigerant pressure is high. The cooling fan may be commanded ON when the engine is not running under a fan run-on conditions described in the electric cooling fan general description portion of the service manual.

I did all of the diagnostics on different sites without a scanner. It was a defective engine cooling fan. Got another fan and all is well for now. There is a seller on ebay who has great feedback but ignored my messages about the fan problem and basically told me to F off.
 

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A "Pop" from under the hood assuming it is a backfire in the intake indicates a timing issue, either ignition not firing properly or cam timing.
 

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Discussion Starter #6
A "Pop" from under the hood assuming it is a backfire in the intake indicates a timing issue, either ignition not firing properly or cam timing.
That is exactly what I thought too, but it only does it when I turn the A/C on after start up. I have driven it 50 miles today in 93* heat with the A/C on. Runs great shifts great @ 6000 rpm and the A/C compressor cycles on and off like it should. Yesterday it was in the mid 80's. After I replaced the cooling fan with a new one from a different source I stopped at a drive through and ordered lunch, parked in the sun and let it idle for 30+ minutes with the A/C on and had no issues. I actually set up a gopro under the hood. The video indicates the popping sound is coming from under the dash.
 

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NVH diagnosis can be a PITA, no tech likes looking for NVH.

I would start by disconnecting the underhood vacuum source to the HVAC control unit to see if that eliminates it.

Unfortunately intermittents whether they are driveabilty or noise related are hard to diagnose if you cannot duplicate the problem, when I have these issues I know in my head the issue will eventually get worse and then it will become easier to locate and repair.

For the last 4 years on/off I have been trying to diagnose an erratic idle condition that only occurs on initial startup and then goes away as the engine warms up, does it in winter and summer.
I was never able to actually see/find anything that would be causing the problem with the scanner and there were no vacuum leaks (which is what I originally thought it would be).
Three weeks ago I connected the scanner again and finally found what appears to be the issue, TPS voltage was moving on its own without touching the throttle.
Do not know if that is 100% yet since I cannot find a replacement TPS.
Bought two "Ultra Pro" (all they had listed, $10.00 each) from Rock Auto and although the listing is correct the parts were not, the OE connector is too large for the TPS they sent, Advance has no listing, Discontinued from Mopar, found a Santech from Autozone, it is still in the delivery stage, so...
I am watching one on eBay that is an aftermarket NOS but very old looking.
 

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Discussion Starter #8
Well NAJ, This car was inherited by my son in law from his grandma. It has 89,000 original miles, I have all of the maintenance records (it was a hertz rental). Every time I repair something on this $500 beater I think about selling it before something else goes T.U. But when it's working good I really enjoy driving it. I have been racing cars for nearly 50 years and these little buggers handle great with some fat, sticky tires. I have replaced the drivers seat with one from a 2010 Challenger, much more comfortable (a simple conversion) and I just ordered new rear shocks. The popping sound will either stop (ha ha) get worse (no doubt) or the thing will die, (don't give a F at this point, LOL). Until then I am going to drive it like I stole it and enjoy it as long as I can. Thank you for your help. Now I can get back to my '86 GLH and diagnose the annoying squeak coming from the left front suspension on my '07 Charger and finish building the 302 for my '86 Mustang. I am a glutton for punishment, 🔧on :poop:
 

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Just one other thing, since it only makes the "Pop" sound when you turn on the A/C after start up the noise may be caused by a sticking mode/blend door that is snapping open instead of opening slowly/gently.
 

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Discussion Starter #10
Just one other thing, since it only makes the "Pop" sound when you turn on the A/C after start up the noise may be caused by a sticking mode/blend door that is snapping open instead of opening slowly/gently.
THANK YOU. That may explain why the popping sound is different every time. I truly appreciate your assistance with these projects.
 
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