QuestionI have been having problems with my 99 Chrysler 300M. We noticed, for the last couple of months, a little bit of a ticking noise when the electric fan(s) engaged. I thought it was something small maybe inside the shroud somewhere and I guess I just told myself it would go away.
A couple of days ago, my wife was driving it and she was getting hot so she rolled up the windows and turned on the A/C and it wasn't cold. She turned it off and got to her destination where she rolled the windows back down and was waiting in the parking lot with the car running for about 2-3 minutes. She heard a "ding" and looked at the temp gauge and it was in the red. Of course she immediately shut it down and called me. I was told that a good way to check if the fans were working was to turn the A/C on and look because they will be on for sure if the A/C is running. I tried it and they did not come on. So I told her to drive it straight home with the A/C controls off and the windows down. She did and for the 11 miles back home it ran perfectly fine either at or below the middle of the gauge.
I popped the hood here in the drive while I was troubleshooting it on the phone with a mechanic buddy in Georgia. He told me the obvious first... reach inside the shroud (turned off of course) and wiggle the blades to see if they are loose or broke. Sure enough, the drivers side was totally broke off 3/4" around the attaching nut and the passenger side blade was very "wobbly". He said "there it is... replace the fans. So I found one on ebay and bought it instantly. It came today and I installed it this eve. I made the mistake of not testing the fans before I put them in and now they are not working either. My A/C seems to have a light "click" like the compressor is engaging, but it is still not cold. I tested the old fans out of car on the bench and outside of the one with no blades making a lot of noise running raw... they both seem to take power and the solid one almost lifted the whole unit up off the bench. So I know it would have taken the power while in the vehicle, but it seems that something has happened that affects both the A/C and the fan module from operating correctly - or at least I know now that the fans weren't getting power for sure.
I read a little on this in my huge service manual and it talks of the relays, speed output sensor, and temperature sending unit. What would cause both of them to stop working and would they stay that way even after the bad fans are replaced? I read here about high pressure and low pressure sides have differences and setting the system haywire too. I am totally lost on where to go from here and desperately need some help.
I also better tell you that for the same couple months leading up to this, but not on a regular basis, the car would feel and sound like it was high revving but the rpm gauge did not change. We would turn it off and back on and it would be gone. Could this just have been the fans engaging and that bad/bare one spinning fast and vibrating loud?
Thanks for your time and all of your help either way.
Jeff
AnswerHi Jeff,
Thanks for the very detailed report. I trust that you have tried out the replacement unit to see that its fan motors are OK. I am slightly limited in only having the '98 manual for the LH cars of which the 300M is also, I believe, like the Intrepid and the Concorde. In '98 there was both a high and low speed fan relay in the power distribution center box under the hood near the battery. In theory the fan relays should be activated when you turn on the A/C or the windshield defrost setting and so the fans should come on with the compressor,too. But I can't be sure whether the fans are cancelled if, for example, there is too little refrigerant in the system which automatically cancels the A/C compressor relay from activating the compressor. If you will watch the belt drive end of the compressor you will be able to notice if the compressor is activated because the clutch is visible in that the compressor will not rotate while you have the engine idling (but the pulley will of course be turned by the drive belt) but when a helper (say your wife) asks for defrost or A/C cooling then if the relay energizes the clutch you will notice that the round part adjacent to the belt pulley will suddenly begin to spin if indeed the clutch has been deployed. And it is a fairly loud click and the engine may momentarily slow down from the additional load. So I would first check that out. If it doesn't deploy then I suspect you are low on refrigerant. Once you recharge the system so as to get the clutch to work, it may turn out that will cause the fan relays to work and thus the fans themselves as well. Of course regardless of the A/C situation when the engine coolant gets up to around 210F one of the fans should activate (this might be at the point where the temp gauge reaches 3/4 scale) and if it goes to 220F then the second fan will also come on. That action is mediated by the coolant temp sensor located on the engine near the manifold to which the top radiator hose is attached. Those can become inaccurate which might also explain why the relays for the fan aren't working.
Of course the fan fuses have to not be blown, and given the somewhat mechanically damaged status of the old fan set up it may well be the problem is just blown fan fuses. In the '98 manual these are shown to be fuses B and E located in the power distribution center under the hood where the relays are located, so check those fuses first thing. Also fuse 21 under the dash is in the circuit to provide power to actuate the fan relays so take a look at that one.
Finally if none of these solve the problem I would suggest that you get a readout of the memory of the powertrain controller for the presence of any 4-digit fault codes. If there is an Autozone Parts store near you they often will doe a free readout. Or a shop might offer a "special" for around $40. Get the actual code numbers, what they mean or are titled, what they suggest needs to be done, and how much. Then if you want to verify that with me, write back and tell me what the situation is for a comparison of what you were told against what the shop manuals says for those codes.
