2007 Town Car Radiator Fan Signal to operate control module??

Hally

New member
Recently the cooling fan in front of the radiator seems not to operate. Does anyone know what kind of signal comes out of the PCM to activate the fan control module? According to the book it is a variable signal which causes the fan to run at certain speeds, etc. Would I be able to see this signal on an analog voltmeter? Or, is a scope necessary to watch for pulses at a certain frequency? The local dealer says that the fan motor itself caused the fan control module to fail so now both fan and control module needs to be replaced at a cost of $1350. Sounds kind of bogus to me. The fan will run when hot wired to a 12VDC source. I've checked all the fuses etc associated with this fan and all are good. And voltage is present at the connector going into the fan control module. Thanks for any help or comments.
 

Bangster

New member
Sounds like there is 1 to many digits in that price. This is a pretty easy to change item (shouldn't be more than 2 hours labor, which is probably 200 dollars), the Dorman with the controller is 125 bucks. Dorman also sells the controller alone, it is 108 bucks (it MIGHT be an improved design).

If the fan does start pulling more amps especially at startup as it wears and ages then it can cause the control module to go (this is very common in the blower motor).

It is a pwm signal, you would need a scope.

Since you have already hotwired the fan to prove it still works, you seem like you could probably also replace the controller, or the entire thing with a fan that includes the controller.
 

Hally

New member
Thanks for your comments and suggestions. There are definitely one too many digits in the dealer quoted price. Reading the factory manual (trying to!) it sounds like in order to change the fan will require draining radiator. I should probably change that fluid anyway, but really didn't want to get into things quite that far. Is it true that whenever the A/C compressor is switched on the radiator fan should also run? I'm getting conflicting information on that. Somewhere I think I read that above 47mph that fan will turn off. And I don't suppose there is a way to manually turn on the radiator fan via some diagnostic tool??
 

Bangster

New member
That is about right, if the AC is on, then the cooling fan will also be on at some speed, but once over a certain speed then it can be commanded off/slower. Since yours is a variable speed fan (not low and high like the pre 03 cars) AC doesn't always mean fastest speed for the fan. On my older cars I could disconnect the temperature sender to force the fan on, but yours uses the CHT, and I am not sure what it would do with the it disconnected (it is on the drivers side head right behind the alternator).

You MIGHT need to drain a little coolant if you have to take off the upper radiator hose, and not sure where the degas tank is (on my 2000 it is on the fan), but there are two bolts holding it in towards the top, then it slides into some slots on the radiator. I have done the cooling fan in my 2000 Grand Marquis without the radiator, and my 97 Mark VIII as well.
 

Hally

New member
Thanks for this additional information. I'm not sure what the CHT is and how I would (if I could) command the radiator fan to run at a certain speed or off/on. I see you have a 1997 Mark. I had a 1998 Mark for a couple of years and liked it pretty much but had to trade it on a TC for more room to move to TX from IL. One complaint I had with the Mark was it seemed extremely noisy inside the car. Seemed like it could have used more sound deadning insulation between the firewall and cab. I also didn't like the constant up/down of the air ride because the compressor was SO noisy. Sounded like a jack hammer. So, I disconnected the signal from the computer and put in an on/off switch to re-enable if desired. Another thing I thought was quite amazing about that car was that when you got it going on an open stretch it just wanted to continue rolling which required you to remember to brake for the stop signs! Quite good on fuel economy as I recall and the gas gauge stayed on full for at least 100 miles. I'd kind of like to have another, but they are scarce here in TX. I think I've only seen two or three in the 8 years I've been here.
 
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