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Chris (aka- Moose)
Chris (aka- Moose), Mercury Technician
Category: Mercury
Satisfied Customers: 47649
Experience:  16 years experience with Mercury
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Hey,I have a 2007 Merc Grand Marquis LS with 70K miles

Customer Question

I have a 2007 Merc Grand Marquis LS with 70K miles on it. The first problem I had was my engine RPM were running so low the engine chattered. Next started running real hot. Compressor motor started smoking. Now, it seems the thermostat is sticking and not allowing coolant to pass through at the proper temps. I have been reading of escalating problems with these cars once they overheat. Now, the sensor that controls the fan motor is not working properly. There is power into it but nothing going to ground. You say there is no cooling fan relay but all trouble shooting sights are saying to replace it with a part price of 100-150. One says to replace the thermostatic fan control with an adjustable one, but the adjustable one has no markings on it, just a set screw. Can I expect ongoing problems with overheating like many seem to have?
Submitted: 2 years ago.
Category: Mercury
Customer: replied 2 years ago.
Do you think the fan relay needs to be replaced or the thermostatic fan control? Should I expect more problems in the future or are there further measures I should take?
Expert:  Chris (aka- Moose) replied 2 years ago.
Hello, I'm Chris. Thanks for seeking us for help.
You need to address these concerns one by one. You stated the thermostat is sticking, you need to address that prior to the fan. Next you mentioned the idle speed is to low which can cause the water pump to run to slow. SO you need to get the rpm right. If there are no warning lights on, then clean the MAF sensor and throttle body.
Does the fan work when the AC is used, if the AC still works?
You want a excellent 5 star answer & I would like to be rated the same for providing it. Consider I don't know your skill level & I can't see, smell, hear, or touch the vehicle. It may take a few back and forth replies. Try your best to respond with good detail so I can do the same. I normally log in at 3pm and work late. A rating is required. Your rating me, what I type. I am not an employee of this website, nor have control over the fees or the time it took to get a response. If you rate negative or not at all you still paid, but I get nothing. I want you pleased with me and my efforts, so let me know if your experience here has come up short.
Thanks Chris
Customer: replied 2 years ago.
I think what was happening at first was that the air compressor motor was locking up and dragging down the engine because the serpentine belt would not let everything else run uninhibited. The AC works -- with a new compresseor motor. The fan only runs because of a jumper between the place where the power goes into the switch and to the battery. I am replacing the thermostat tomorrow. The engine fan does run, but does not get a signal to run or stop. Is there a cooling fan relay (or not as you stated in another post). Will a thermostatic fan control (like part 226203 on Advanced Auto Parts) fix the problem. Some places have seemed to say yes. The MAF sensor and throttle body have been blown out to ensure no debris, but the area looks remarkably clean. Ford strongly recommends not adjusting the throttle because it is supposed to be automatic. With the fan jumpered and the Compressor motor replaced, the RPM issue seems resolved. I also saw where one person ended up replacing the radiator because of the plastic connections caused freon leaks after overheating. When the engine did overheat, I was able to stop the car quickly, had minimal water loss, but it did peg high briefly.
Customer: replied 2 years ago.
There was a form I had to fill out that asked what was the sequence of events and what actions had been taken. Can you see that?
Expert:  Chris (aka- Moose) replied 2 years ago.
Open the file below to see the Ford fan diagram.
no relays are used in this fan circuit. If the fan is not getting commanded on, then the PCM is bad. The ETB and MAF sensor need to be cleaned using chemicals and not air, air already flows across them.
Based on your comments it does appear you are thinking I know more about prior discussions or what you know. Below is an image showing exactly what my screen looks like so you know what I can see and base my response from.
Customer: replied 2 years ago.
The dropbox you showed doesn't have the last responses I made. I think you didn't get all I said at first, I read another answer you gave for a Grand Marquis overheating. Everyone keeps trying to sell me a fan motor relay. In the last part, I asked about a thermostatic fan control. I have seen where two people have put them in and say it works. Advanced Auto Parts, under the part number posted previously in customer reviews, explains how he installed one. Why would the ETB and MAF sensor need chemical cleaning. This I don't know what to use or how. I have put engine cleaner in initially when the car was just chattering because I thought it could be bad gas or something. Could you please go back and answer the embedded questions?
Expert:  Chris (aka- Moose) replied 2 years ago.
There is not a engine cooling fan relay for this model, you can purchase one, but that will just prove that advance is wrong because there is no where on the car to put it. I have never rewired the fan to work with aftermarket parts, so I have no input on the thermostatic fan control, much less it would also need to be wired in the AC for it to run with the compressor on. The ETB and MAF sensor no longer need to be cleaned since you included additional information that the compressor was locked up and dragging the motor down, effecting the idle speed. Are there any other questions I have missed?
Customer: replied 2 years ago.
I am finding ECMs for up to 1000 but not really a PCM. Any idea where to look for parts except Motorcraft.
Expert:  Chris (aka- Moose) replied 2 years ago.
An ECM and PCM are the same, Ford calls it the PCM. Have you tried they have aftermarket PCMs.
Customer: replied 2 years ago.
I did, but didn't find one. Just gave me everything that had module in it. Ford looks like it is about $1000 and that seems ridiculous. Was just check JCWhitney. Any idea what a reasonable price would be. The only other question I had was about extraneous damage. Seems like others were having to replace radiators and connections that were part plastic because of warping, I guess.
Customer: replied 2 years ago.
Do you know what the difference is between these two? Besides the $115? Even put in my VIN and they came up with two.
12A650 Powertrain Control Module
4.6 Single Over Head Cam EFI Romeo 4.6 Single Over Head Cam EFI ; 7FB1BF0505 (NCP1) $970.27
12A650 Powertrain Control Module
4.6 Single Over Head Cam EFI Romeo 4.6 Single Over Head Cam EFI ; 7FB1HF0505 (SKG1) $855.48
Expert:  Chris (aka- Moose) replied 2 years ago.
I see no need to replace the radiator unless its clogged or leaking, and clogging should not be a factor yet at this age and mileage.
12A650 is the part number for the PCM, in every Ford Lincoln Mercury vehicle. The first 4 letters and numbers are the year make and model and system. The last 2 letters are the release date.
Below is the one you need and the build date is on the label in the door jam.
Flex fuel option is the only difference I can find in the PCMs.
Customer: replied 2 years ago.
That looks totally different from what you see on RockAuto DORMAN Part # ***** {#6W1Z8B658AC} for about 100. Totally different animal.Which is the one for the non-Flex Fuel Engine?
Expert:  Chris (aka- Moose) replied 2 years ago.
I would need your build date and vin# ***** find that information.
6W1Z8B658AC is a cooling fan module, the same one shown in the previous Ford wire diagram I sent.
Customer: replied 2 years ago.
VIN: 2mefm75v87x630709 don't have date but know from VIN it is not Flex Fuel
So do I need cooling fan module or the powertrain control module? Sorry, it's just getting really late.
Expert:  Chris (aka- Moose) replied 2 years ago.
The only way to know for sure which is needed fan module, or PCM is to perform diag shown below.
Your vin says it is a FFV (8th vin # *****)
That would mean you need this one.