# 97 grand marquis.thump, every 10 second or so???????????



## forresth (Feb 19, 2010)

does it do it if you unplug the compressor clutch?


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## nap (Dec 4, 2007)

yes, very familiar.

any idea what an AC compressor looks like? Even if not, since it is doing this, you should be able to see it as it cycles so,

open the hood, start the engine and watch (NO NOT TOUCH) the front of the engine. If it is the AC compressor, you should be able to see one of the pulleys go around, then stop, then spin again, and on and on. A lot of them tend to make a kind of rattle sound when they are spinning.


If that is it, yes, you are low on refrigerant and would need at least a recharge. You have a leak somewhere.


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## bsa_bob (Oct 31, 2010)

*occasional anti-freeze smell 97 marquis*

This car after it sets a month or two will give off a strong smell of anti-freeze when you start it up-------after a day or two on the road, it [smell] leaves the car. Nothing on the floor, nothing showing leakage on the motor,or hoses.And its not low when the oil is changed. nothing on the w/s to make me think its a leaking heater core.
Man those are expensive , and the whole dash comes down. i saw some pictures of the job. like i say i can't smell anything now.


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## bsa_bob (Oct 31, 2010)

forresth said:


> does it do it if you unplug the compressor clutch?


 If i just use the heat on manual.......no thump.


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## bsa_bob (Oct 31, 2010)

*two posts entwined here very sorry all.*

This fella said i should not put to much freon in it with out the gauges,.i could lock the compressor up! I have added freon since the 70s.and haven't locked one up yet. Is this a true staement.cause i don't know any help appreciated greatly bob s


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## nap (Dec 4, 2007)

you can destroy a compressor by adding freon improperly or overcharging. 

but,,with that, I rarely use gauges myself.


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## bsa_bob (Oct 31, 2010)

thanks for the help all!:thumbup:


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## ianc435 (Jun 12, 2010)

bsa_bob said:


> I have a thump and it slows the engine just a bit when it clunks, A young fella told me it sounded like a power surge.This being caused by a low freon charge.And the car is an automatic teemperature control. he believed the the A/C compressor was short cycling.
> 
> Does this ring true with any of you.


Disconnect the mag coil on the. Compressor and drive. Or you could just turn of climate control. Could have a bad body control module. The pulley will always spin. As far a 'slugging the compressor'. It depends on the type of compressor. Recip in auto can be dammged. Scroll and screws good luck trying to break those.


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